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Joyce LR, Youngblom MA, Cormaty H, Gartstein E, Barber KE, Akins RL, Pepperell C, Palmer KL. Erratum for Joyce et al., "Comparative Genomics of Streptococcus oralis Identifies Large Scale Homologous Recombination and a Genetic Variant Associated with Infection". mSphere 2024:e0026624. [PMID: 38651872 DOI: 10.1128/msphere.00266-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024] Open
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Sharon BM, Arute AP, Nguyen A, Tiwari S, Reddy Bonthu SS, Hulyalkar NV, Neugent ML, Palacios Araya D, Dillon NA, Zimmern PE, Palmer KL, De Nisco NJ. Genetic and functional enrichments associated with Enterococcus faecalis isolated from the urinary tract. mBio 2023; 14:e0251523. [PMID: 37962362 PMCID: PMC10746210 DOI: 10.1128/mbio.02515-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 10/05/2023] [Indexed: 11/15/2023] Open
Abstract
IMPORTANCE Urinary tract infection (UTI) is a global health issue that imposes a substantial burden on healthcare systems. Women are disproportionately affected by UTI, with >60% of women experiencing at least one UTI in their lifetime. UTIs can recur, particularly in postmenopausal women, leading to diminished quality of life and potentially life-threatening complications. Understanding how pathogens colonize and survive in the urinary tract is necessary to identify new therapeutic targets that are urgently needed due to rising rates of antimicrobial resistance. How Enterococcus faecalis, a bacterium commonly associated with UTI, adapts to the urinary tract remains understudied. Here, we generated a collection of high-quality closed genome assemblies of clinical urinary E. faecalis isolated from the urine of postmenopausal women that we used alongside detailed clinical metadata to perform a robust comparative genomic investigation of genetic factors that may be involved in E. faecalis survival in the urinary tract.
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Affiliation(s)
- Belle M. Sharon
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Amanda P. Arute
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Amber Nguyen
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Suman Tiwari
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | | | - Neha V. Hulyalkar
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Michael L. Neugent
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Dennise Palacios Araya
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Nicholas A. Dillon
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Philippe E. Zimmern
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Nicole J. De Nisco
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Christensen PM, Martin J, Uppuluri A, Joyce LR, Wei Y, Guan Z, Morcos F, Palmer KL. Lipid discovery enabled by sequence statistics and machine learning. bioRxiv 2023:2023.10.12.562061. [PMID: 37873101 PMCID: PMC10592805 DOI: 10.1101/2023.10.12.562061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Bacterial membranes are complex and dynamic, arising from an array of evolutionary pressures. One enzyme that alters membrane compositions through covalent lipid modification is MprF. We recently identified that Streptococcus agalactiae MprF synthesizes lysyl-phosphatidylglycerol (Lys-PG) from anionic PG, and a novel cationic lipid, lysyl-glucosyl-diacylglycerol (Lys-Glc-DAG), from neutral glycolipid Glc-DAG. This unexpected result prompted us to investigate whether Lys-Glc-DAG occurs in other MprF-containing bacteria, and whether other novel MprF products exist. Here, we studied protein sequence features determining MprF substrate specificity. First, pairwise analyses identified several streptococcal MprFs synthesizing Lys-Glc-DAG. Second, a restricted Boltzmann machine-guided approach led us to discover an entirely new substrate for MprF in Enterococcus , diglucosyl-diacylglycerol (Glc2-DAG), and an expanded set of organisms that modify glycolipid substrates using MprF. Overall, we combined the wealth of available sequence data with machine learning to model evolutionary constraints on MprF sequences across the bacterial domain, thereby identifying a novel cationic lipid.
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Upreti C, Kumar P, Durso LM, Palmer KL. CRISPR-Cas inhibits plasmid transfer and immunizes bacteria against antibiotic resistance acquisition in manure. bioRxiv 2023:2023.09.26.559507. [PMID: 37808752 PMCID: PMC10557689 DOI: 10.1101/2023.09.26.559507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
The horizontal transfer of antibiotic resistance genes among bacteria is a pressing global issue. The bacterial defense system CRISPR-Cas acts as a barrier to the spread of antibiotic resistance plasmids, and CRISPR-Cas-based antimicrobials can be effective to selectively deplete antibiotic-resistant bacteria. While significant surveillance efforts monitor the spread of antibiotic-resistant bacteria in the clinical context, a major, often overlooked aspect of the issue is resistance emergence in agriculture. Farm animals are commonly treated with antibiotics, and antibiotic resistance in agriculture is on the rise. Yet, CRISPR-Cas efficacy has not been investigated in this setting. Here, we evaluate the prevalence of CRISPR-Cas in agricultural Enterococcus faecalis strains and its anti-plasmid efficacy in an agricultural niche - manure. We show that the prevalence of CRISPR-Cas subtypes is similar between clinical and agricultural E. faecalis strains. CRISPR-Cas was found to be an effective barrier against resistance plasmid transfer in manure, with improved effect as time progressed. CRISPR-based antimicrobials to cure resistant E. faecalis of erythromycin resistance was limited by delivery efficiency of the CRISPR antimicrobial in manure. However, immunization of bacteria against resistance gene acquisition in manure was highly effective. Together, our results show that E. faecalis CRISPR-Cas is prevalent and effective in an agricultural setting, and has the potential to be utilized for depleting antibiotic-resistant populations. Our work has broad implications for tackling antibiotic resistance in the increasingly relevant agricultural setting, in line with a OneHealth approach.
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Affiliation(s)
- Chahat Upreti
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas
| | - Pranav Kumar
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas
| | - Lisa M. Durso
- U.S. Department of Agriculture, Agricultural Research Service, Agroecosystem Management Unit, 251 Filley Hall, UNL East Campus, Lincoln, Nebraska
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas
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Olaitan AO, Dureja C, Youngblom MA, Topf MA, Shen WJ, Gonzales-Luna AJ, Deshpande A, Hevener KE, Freeman J, Wilcox MH, Palmer KL, Garey KW, Pepperell CS, Hurdle JG. Decoding a cryptic mechanism of metronidazole resistance among globally disseminated fluoroquinolone-resistant Clostridioides difficile. Nat Commun 2023; 14:4130. [PMID: 37438331 DOI: 10.1038/s41467-023-39429-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 06/13/2023] [Indexed: 07/14/2023] Open
Abstract
Severe outbreaks and deaths have been linked to the emergence and global spread of fluoroquinolone-resistant Clostridioides difficile over the past two decades. At the same time, metronidazole, a nitro-containing antibiotic, has shown decreasing clinical efficacy in treating C. difficile infection (CDI). Most metronidazole-resistant C. difficile exhibit an unusual resistance phenotype that can only be detected in susceptibility tests using molecularly intact heme. Here, we describe the mechanism underlying this trait. We find that most metronidazole-resistant C. difficile strains carry a T-to-G mutation (which we term PnimBG) in the promoter of gene nimB, resulting in constitutive transcription. Silencing or deleting nimB eliminates metronidazole resistance. NimB is related to Nim proteins that are known to confer resistance to nitroimidazoles. We show that NimB is a heme-dependent flavin enzyme that degrades nitroimidazoles to amines lacking antimicrobial activity. Furthermore, occurrence of the PnimBG mutation is associated with a Thr82Ile substitution in DNA gyrase that confers fluoroquinolone resistance in epidemic strains. Our findings suggest that the pandemic of fluoroquinolone-resistant C. difficile occurring over the past few decades has also been characterized by widespread resistance to metronidazole.
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Affiliation(s)
- Abiola O Olaitan
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Chetna Dureja
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
| | - Madison A Youngblom
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Madeline A Topf
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Wan-Jou Shen
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
| | - Anne J Gonzales-Luna
- Department of Pharmacy Practice and Translational Research, University of Houston College of Pharmacy, Houston, TX, USA
| | - Aditi Deshpande
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
| | - Kirk E Hevener
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jane Freeman
- Department of Microbiology, Leeds Teaching Hospitals Trust, Leeds, UK
- Healthcare Associated Infection Research Group, School of Medicine, University of Leeds, Leeds, UK
| | - Mark H Wilcox
- Department of Microbiology, Leeds Teaching Hospitals Trust, Leeds, UK
- Healthcare Associated Infection Research Group, School of Medicine, University of Leeds, Leeds, UK
| | - Kelli L Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Kevin W Garey
- Department of Pharmacy Practice and Translational Research, University of Houston College of Pharmacy, Houston, TX, USA
| | - Caitlin S Pepperell
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.
- Department of Medicine, Division of Infectious Diseases, University of Wisconsin-Madison, Madison, WI, USA.
| | - Julian G Hurdle
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA.
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Huo W, Price VJ, Sharifi A, Zhang MQ, Palmer KL. Enterococcus faecalis Strains with Compromised CRISPR-Cas Defense Emerge under Antibiotic Selection for a CRISPR-Targeted Plasmid. Appl Environ Microbiol 2023; 89:e0012423. [PMID: 37278656 PMCID: PMC10304774 DOI: 10.1128/aem.00124-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023] Open
Abstract
Enterococcus faecalis is a Gram-positive bacterium that natively colonizes the human gastrointestinal tract and opportunistically causes life-threatening infections. Multidrug-resistant (MDR) E. faecalis strains have emerged that are replete with mobile genetic elements (MGEs). Non-MDR E. faecalis strains frequently possess CRISPR-Cas systems, which reduce the frequency of MGE acquisition. We demonstrated in previous studies that E. faecalis populations can transiently maintain both a functional CRISPR-Cas system and a CRISPR-Cas target. In this study, we used serial passage and deep sequencing to analyze these populations. In the presence of antibiotic selection for the plasmid, mutants with compromised CRISPR-Cas defense and enhanced ability to acquire a second antibiotic resistance plasmid emerged. Conversely, in the absence of selection, the plasmid was lost from wild-type E. faecalis populations but not E. faecalis populations that lacked the cas9 gene. Our results indicate that E. faecalis CRISPR-Cas can become compromised under antibiotic selection, generating populations with enhanced abilities to undergo horizontal gene transfer. IMPORTANCE Enterococcus faecalis is a leading cause of hospital-acquired infections and disseminator of antibiotic resistance plasmids among Gram-positive bacteria. We have previously shown that E. faecalis strains with an active CRISPR-Cas system can prevent plasmid acquisition and thus limit the transmission of antibiotic resistance determinants. However, CRISPR-Cas is not a perfect barrier. In this study, we observed populations of E. faecalis with transient coexistence of CRISPR-Cas and one of its plasmid targets. Our experimental data demonstrate that antibiotic selection results in compromised E. faecalis CRISPR-Cas function, thereby facilitating the acquisition of additional resistance plasmids by E. faecalis.
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Affiliation(s)
- Wenwen Huo
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Valerie J. Price
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Ardalan Sharifi
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Michael Q. Zhang
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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Wei Y, Sturges CI, Palmer KL. Human Serum Supplementation Promotes Streptococcus mitis Growth and Induces Specific Transcriptomic Responses. Microbiol Spectr 2023; 11:e0512922. [PMID: 37014220 PMCID: PMC10269507 DOI: 10.1128/spectrum.05129-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/01/2023] [Indexed: 04/05/2023] Open
Abstract
Streptococcus mitis is a normal member of the human oral microbiota and a leading opportunistic pathogen causing infective endocarditis (IE). Despite the complex interactions between S. mitis and the human host, understanding of S. mitis physiology and its mechanisms of adaptation to host-associated environments is inadequate, especially compared with other IE bacterial pathogens. This study reports the growth-promoting effects of human serum on S. mitis and other pathogenic streptococci, including S. oralis, S. pneumoniae, and S. agalactiae. Using transcriptomic analyses, we identified that, with the addition of human serum, S. mitis downregulates uptake systems for metal ions and sugars, fatty acid biosynthetic genes, and genes involved in stress response and other processes related with growth and replication. S. mitis upregulates uptake systems for amino acids and short peptides in response to human serum. Zinc availability and environmental signals sensed by the induced short peptide binding proteins were not sufficient to confer the growth-promoting effects. More investigation is required to establish the mechanism for growth promotion. Overall, our study contributes to the fundamental understanding of S. mitis physiology under host-associated conditions. IMPORTANCE S. mitis is exposed to human serum components during commensalism in the human mouth and bloodstream pathogenesis. However, the physiological effects of serum components on this bacterium remain unclear. Using transcriptomic analyses, S. mitis biological processes that respond to the presence of human serum were revealed, improving the fundamental understanding of S. mitis physiology in human host conditions.
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Affiliation(s)
- Yahan Wei
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Camille I. Sturges
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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Sharon BM, Hulyalkar NV, Zimmern PE, Palmer KL, De Nisco NJ. Inter-species diversity and functional genomic analyses of closed genome assemblies of clinically isolated, megaplasmid-containing Enterococcus raffinosus Er676 and ATCC49464. Access Microbiol 2023; 5:acmi000508.v3. [PMID: 37424546 PMCID: PMC10323788 DOI: 10.1099/acmi.0.000508.v3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 03/10/2023] [Indexed: 07/11/2023] Open
Abstract
Enterococcus raffinosus is an understudied member of its genus possessing a characteristic megaplasmid contributing to a large genome size. Although less commonly associated with human infection compared to other enterococci, this species can cause disease and persist in diverse niches such as the gut, urinary tract, blood and environment. Few complete genome assemblies have been published to date for E. raffinosus . In this study, we report the complete assembly of the first clinical urinary E. raffinosus strain, Er676, isolated from a postmenopausal woman with history of recurrent urinary tract infection. We additionally completed the assembly of clinical type strain ATCC49464. Comparative genomic analyses reveal inter-species diversity driven by large accessory genomes. The presence of a conserved megaplasmid indicates it is a ubiquitous and vital genetic feature of E. raffinosus . We find that the E. raffinosus chromosome is enriched for DNA replication and protein biosynthesis genes while the megaplasmid is enriched for transcription and carbohydrate metabolism genes. Prophage analysis suggests that diversity in the chromosome and megaplasmid sequences arises, in part, from horizontal gene transfer. Er676 demonstrated the largest genome size reported to date for E. raffinosus and the highest probability of human pathogenicity. Er676 also possesses multiple antimicrobial resistance genes, of which all but one are encoded on the chromosome, and has the most complete prophage sequences. Complete assembly and comparative analyses of the Er676 and ATCC49464 genomes provide important insight into the inter-species diversity of E. raffinosus that gives it its ability to colonize and persist in the human body. Investigating genetic factors that contribute to the pathogenicity of this species will provide valuable tools to combat diseases caused by this opportunistic pathogen.
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Affiliation(s)
- Belle M. Sharon
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Neha V. Hulyalkar
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Philippe E. Zimmern
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Nicole J. De Nisco
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Kirsch JM, Ely S, Stellfox ME, Hullahalli K, Luong P, Palmer KL, Van Tyne D, Duerkop BA. Targeted IS-element sequencing uncovers transposition dynamics during selective pressure in enterococci. PLoS Pathog 2023; 19:e1011424. [PMID: 37267422 PMCID: PMC10266640 DOI: 10.1371/journal.ppat.1011424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 06/14/2023] [Accepted: 05/15/2023] [Indexed: 06/04/2023] Open
Abstract
Insertion sequences (IS) are simple transposons implicated in the genome evolution of diverse pathogenic bacterial species. Enterococci have emerged as important human intestinal pathogens with newly adapted virulence potential and antibiotic resistance. These genetic features arose in tandem with large-scale genome evolution mediated by mobile elements. Pathoadaptation in enterococci is thought to be mediated in part by the IS element IS256 through gene inactivation and recombination events. However, the regulation of IS256 and the mechanisms controlling its activation are not well understood. Here, we adapt an IS256-specfic deep sequencing method to describe how chronic lytic phage infection drives widespread diversification of IS256 in E. faecalis and how antibiotic exposure is associated with IS256 diversification in E. faecium during a clinical human infection. We show through comparative genomics that IS256 is primarily found in hospital-adapted enterococcal isolates. Analyses of IS256 transposase gene levels reveal that IS256 mobility is regulated at the transcriptional level by multiple mechanisms in E. faecalis, indicating tight control of IS256 activation in the absence of selective pressure. Our findings reveal that stressors such as phages and antibiotic exposure drives rapid genome-scale transposition in the enterococci. IS256 diversification can therefore explain how selective pressures mediate evolution of the enterococcal genome, ultimately leading to the emergence of dominant nosocomial lineages that threaten human health.
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Affiliation(s)
- Joshua M. Kirsch
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
| | - Shannon Ely
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
| | - Madison E. Stellfox
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Karthik Hullahalli
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Phat Luong
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
| | - Kelli L. Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Daria Van Tyne
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Breck A. Duerkop
- Department of Immunology and Microbiology, University of Colorado–Anschutz Medical Campus, School of Medicine, Aurora, Colorado, United States of America
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Sharon BM, Arute AP, Nguyen A, Tiwari S, Bonthu SSR, Hulyalkar NV, Neugent ML, Araya DP, Dillon NA, Zimmern PE, Palmer KL, De Nisco NJ. Functional and genetic adaptations contributing to Enterococcus faecalis persistence in the female urinary tract. bioRxiv 2023:2023.05.18.541374. [PMID: 37293065 PMCID: PMC10245761 DOI: 10.1101/2023.05.18.541374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Enterococcus faecalis is the leading Gram-positive bacterial species implicated in urinary tract infection (UTI). An opportunistic pathogen, E. faecalis is a commensal of the human gastrointestinal tract (GIT) and its presence in the GIT is a predisposing factor for UTI. The mechanisms by which E. faecalis colonizes and survives in the urinary tract (UT) are poorly understood, especially in uncomplicated or recurrent UTI. The UT is distinct from the GIT and is characterized by a sparse nutrient landscape and unique environmental stressors. In this study, we isolated and sequenced a collection of 37 clinical E. faecalis strains from the urine of primarily postmenopausal women. We generated 33 closed genome assemblies and four highly contiguous draft assemblies and conducted a comparative genomics to identify genetic features enriched in urinary E. faecalis with respect to E. faecalis isolated from the human GIT and blood. Phylogenetic analysis revealed high diversity among urinary strains and a closer relatedness between urine and gut isolates than blood isolates. Plasmid replicon (rep) typing further underscored possible UT-GIT interconnection identifying nine shared rep types between urine and gut E. faecalis . Both genotypic and phenotypic analysis of antimicrobial resistance among urinary E. faecalis revealed infrequent resistance to front-line UTI antibiotics nitrofurantoin and fluoroquinolones and no vancomycin resistance. Finally, we identified 19 candidate genes enriched among urinary strains that may play a role in adaptation to the UT. These genes are involved in the core processes of sugar transport, cobalamin import, glucose metabolism, and post-transcriptional regulation of gene expression. IMPORTANCE Urinary tract infection (UTI) is a global health issue that imposes substantial burden on healthcare systems. Women are disproportionately affected by UTI with >60% of women experiencing at least one UTI in their lifetime. UTIs can recur, particularly in postmenopausal women, leading to diminished quality of life and potentially life-threatening complications. Understanding how pathogens colonize and survive in the urinary tract is necessary to identify new therapeutic targets that are urgently needed due to rising rates of antimicrobial resistance. How Enterococcus faecalis , a bacterium commonly associated with UTI, adapts to the urinary tract remains understudied. Here, we generated a collection of high-quality closed genome assemblies of clinical urinary E. faecalis isolated from the urine of postmenopausal women that we used alongside detailed clinical metadata to perform a robust comparative genomic investigation of genetic factors that may mediate urinary E. faecalis adaptation to the female urinary tract.
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Joyce LR, Youngblom MA, Cormaty H, Gartstein E, Barber KE, Akins RL, Pepperell CS, Palmer KL. Comparative Genomics of Streptococcus oralis Identifies Large Scale Homologous Recombination and a Genetic Variant Associated with Infection. mSphere 2022; 7:e0050922. [PMID: 36321824 PMCID: PMC9769543 DOI: 10.1128/msphere.00509-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 10/17/2022] [Indexed: 11/07/2022] Open
Abstract
The viridans group streptococci (VGS) are a large consortium of commensal streptococci that colonize the human body. Many species within this group are opportunistic pathogens causing bacteremia and infective endocarditis (IE), yet little is known about why some strains cause invasive disease. Identification of virulence determinants is complicated by the difficulty of distinguishing between the closely related species of this group. Here, we analyzed genomic data from VGS that were isolated from blood cultures in patients with invasive infections and oral swabs of healthy volunteers and then determined the best-performing methods for species identification. Using whole-genome sequence data, we characterized the population structure of a diverse sample of Streptococcus oralis isolates and found evidence of frequent recombination. We used multiple genome-wide association study tools to identify candidate determinants of invasiveness. These tools gave consistent results, leading to the discovery of a single synonymous single nucleotide polymorphism (SNP) that was significantly associated with invasiveness. This SNP was within a previously undescribed gene that was conserved across the majority of VGS species. Using the growth in the presence of human serum and a simulated infective endocarditis vegetation model, we were unable to identify a phenotype for the enriched allele in laboratory assays, suggesting a phenotype may be specific to natural infection. These data highlighted the power of analyzing natural populations for gaining insight into pathogenicity, particularly for organisms with complex population structures like the VGS. IMPORTANCE The viridians group streptococci (VGS) are a large collection of closely related commensal streptococci, with many being opportunistic pathogens causing invasive diseases, such as bacteremia and infective endocarditis. Little is known about virulence determinants in these species, and there is a distinct lack of genomic information available for the VGS. In this study, we collected VGS isolates from invasive infections and healthy volunteers and performed whole-genome sequencing for a suite of downstream analyses. We focused on a diverse sample of Streptococcus oralis genomes and identified high rates of recombination in the population as well as a single genome variant highly enriched in invasive isolates. The variant lies within a previously uncharacterized gene, nrdM, which shared homology with the anaerobic ribonucleoside triphosphate reductase, nrdD, and was highly conserved among VGS. This work increased our knowledge of VGS genomics and indicated that differences in virulence potential among S. oralis isolates were, at least in part, genetically determined.
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Affiliation(s)
- Luke R. Joyce
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Madison A. Youngblom
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Harshini Cormaty
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Evelyn Gartstein
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Katie E. Barber
- Department of Pharmacy Practice, University of Mississippi School of Pharmacy, University of Mississippi, Jackson, Mississippi, USA
| | | | - Caitlin S. Pepperell
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Medicine (Infectious Diseases), School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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Neugent ML, Kumar A, Hulyalkar NV, Lutz KC, Nguyen VH, Fuentes JL, Zhang C, Nguyen A, Sharon BM, Kuprasertkul A, Arute AP, Ebrahimzadeh T, Natesan N, Xing C, Shulaev V, Li Q, Zimmern PE, Palmer KL, De Nisco NJ. Recurrent urinary tract infection and estrogen shape the taxonomic ecology and function of the postmenopausal urogenital microbiome. Cell Rep Med 2022; 3:100753. [PMID: 36182683 PMCID: PMC9588997 DOI: 10.1016/j.xcrm.2022.100753] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 01/28/2022] [Accepted: 09/08/2022] [Indexed: 11/24/2022]
Abstract
Postmenopausal women are severely affected by recurrent urinary tract infection (rUTI). The urogenital microbiome is a key component of the urinary environment. However, changes in the urogenital microbiome underlying rUTI susceptibility are unknown. Here, we perform shotgun metagenomics and advanced culture on urine from a controlled cohort of postmenopausal women to identify urogenital microbiome compositional and function changes linked to rUTI susceptibility. We identify candidate taxonomic biomarkers of rUTI susceptibility in postmenopausal women and an enrichment of lactobacilli in postmenopausal women taking estrogen hormone therapy. We find robust correlations between Bifidobacterium and Lactobacillus and urinary estrogens in women without urinary tract infection (UTI) history. Functional analyses reveal distinct metabolic and antimicrobial resistance gene (ARG) signatures associated with rUTI. Importantly, we find that ARGs are enriched in the urogenital microbiomes of women with rUTI history independent of current UTI status. Our data suggest that rUTI and estrogen shape the urogenital microbiome in postmenopausal women.
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Affiliation(s)
- Michael L Neugent
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Ashwani Kumar
- Eugene McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Neha V Hulyalkar
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Kevin C Lutz
- Department of Mathematical Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Vivian H Nguyen
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Jorge L Fuentes
- Department of Urology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Cong Zhang
- Department of Mathematical Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Amber Nguyen
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Belle M Sharon
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Amy Kuprasertkul
- Department of Urology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Amanda P Arute
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Tahmineh Ebrahimzadeh
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Nitya Natesan
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Chao Xing
- Eugene McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Bioinformatics, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Population and Data Sciences, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Vladimir Shulaev
- Department of Biological Sciences, The University of North Texas, Denton, TX, USA; Advanced Environmental Research Institute, The University of North Texas, Denton, TX, USA
| | - Qiwei Li
- Department of Mathematical Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Philippe E Zimmern
- Department of Urology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kelli L Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Nicole J De Nisco
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA; Department of Urology, The University of Texas Southwestern Medical Center, Dallas, TX, USA.
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13
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Johnson CN, Palacios Araya D, Schink V, Islam M, Mangalea MR, Decurtis EK, Ngo TC, Palmer KL, Duerkop BA. Genetically distant bacteriophages select for unique genomic changes in
Enterococcus faecalis. Microbiologyopen 2022; 11:e1273. [PMID: 35478284 PMCID: PMC8924694 DOI: 10.1002/mbo3.1273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/23/2022] [Accepted: 02/24/2022] [Indexed: 11/10/2022] Open
Abstract
The human microbiota harbors diverse bacterial and bacteriophage (phage) communities. Bacteria evolve to overcome phage infection, thereby driving phage evolution to counter bacterial resistance. Understanding how phages select for genetic alterations in medically relevant bacteria is important as phages become established biologics for the treatment of multidrug‐resistant (MDR) bacterial infections. Before phages can be widely used as standalone or combination antibacterial therapies, we must obtain a deep understanding of the molecular mechanisms of phage infection and how host bacteria alter their genomes to become resistant. We performed coevolution experiments using a single Enterococcus faecalis strain and two distantly related phages to determine how phage pressure impacts the evolution of the E. faecalis genome. Whole‐genome sequencing of E. faecalis following continuous exposure to these two phages revealed mutations previously demonstrated to be essential for phage infection. We also identified mutations in genes previously unreported to be associated with phage infection in E. faecalis. Intriguingly, there was only one shared mutation in the E. faecalis genome that was selected by both phages tested, demonstrating that infection by two genetically distinct phages selects for diverse variants. This knowledge serves as the basis for the continued study of E. faecalis genome evolution during phage infection and can be used to inform the design of future therapeutics, such as phage cocktails, intended to target MDR E. faecalis.
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Affiliation(s)
- Cydney N. Johnson
- Department of Immunology and Microbiology University of Colorado School of Medicine Aurora Colorado USA
| | | | - Viviane Schink
- Department of Immunology and Microbiology University of Colorado School of Medicine Aurora Colorado USA
| | - Moutusee Islam
- Department of Biological Sciences University of Texas at Dallas Richardson Texas USA
| | - Mihnea R. Mangalea
- Department of Immunology and Microbiology University of Colorado School of Medicine Aurora Colorado USA
| | - Emily K. Decurtis
- Department of Biological Sciences University of Texas at Dallas Richardson Texas USA
| | - Tuong‐Vi C. Ngo
- Department of Biological Sciences University of Texas at Dallas Richardson Texas USA
| | - Kelli L. Palmer
- Department of Biological Sciences University of Texas at Dallas Richardson Texas USA
| | - Breck A. Duerkop
- Department of Immunology and Microbiology University of Colorado School of Medicine Aurora Colorado USA
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14
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Joyce LR, Manzer HS, da C. Mendonça J, Villarreal R, Nagao PE, Doran KS, Palmer KL, Guan Z. Identification of a novel cationic glycolipid in Streptococcus agalactiae that contributes to brain entry and meningitis. PLoS Biol 2022; 20:e3001555. [PMID: 35180210 PMCID: PMC8893666 DOI: 10.1371/journal.pbio.3001555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 03/03/2022] [Accepted: 01/26/2022] [Indexed: 12/17/2022] Open
Abstract
Bacterial membrane lipids are critical for membrane bilayer formation, cell division, protein localization, stress responses, and pathogenesis. Despite their critical roles, membrane lipids have not been fully elucidated for many pathogens. Here, we report the discovery of a novel cationic glycolipid, lysyl-glucosyl-diacylglycerol (Lys-Glc-DAG), which is synthesized in high abundance by the bacterium Streptococcus agalactiae (Group B Streptococcus, GBS). To our knowledge, Lys-Glc-DAG is more positively charged than any other known lipids. Lys-Glc-DAG carries 2 positive net charges per molecule, distinct from the widely described lysylated phospholipid lysyl-phosphatidylglycerol (Lys-PG) that carries one positive net charge due to the presence of a negatively charged phosphate moiety. We use normal phase liquid chromatography (NPLC) coupled with electrospray ionization (ESI) high-resolution tandem mass spectrometry (HRMS/MS) and genetic approaches to determine that Lys-Glc-DAG is synthesized by the enzyme MprF in GBS, which covalently modifies the neutral glycolipid Glc-DAG with the cationic amino acid lysine. GBS is a leading cause of neonatal meningitis, which requires traversal of the endothelial blood–brain barrier (BBB). We demonstrate that GBS strains lacking mprF exhibit a significant decrease in the ability to invade BBB endothelial cells. Further, mice challenged with a GBSΔmprF mutant developed bacteremia comparably to wild-type (WT) infected mice yet had less recovered bacteria from brain tissue and a lower incidence of meningitis. Thus, our data suggest that Lys-Glc-DAG may contribute to bacterial uptake into host cells and disease progression. Importantly, our discovery provides a platform for further study of cationic lipids at the host–pathogen interface. Bacterial membrane lipids are critical for membrane bilayer formation, cell division, protein localization, stress responses, and pathogenesis. This study shows that the enzyme MprF in Streptococcus agalactiae synthesizes a novel cationic lipid, Lysyl-Glucosyl-Diacylglycerol, which aids meningitis progression in vivo.
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Affiliation(s)
- Luke R. Joyce
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Haider S. Manzer
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Jéssica da C. Mendonça
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- Rio de Janeiro State University, Roberto Alcântara Gomes Biology Institute, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ricardo Villarreal
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Prescilla E. Nagao
- Rio de Janeiro State University, Roberto Alcântara Gomes Biology Institute, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Kelly S. Doran
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail: (KSD); (KLP); (ZG)
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
- * E-mail: (KSD); (KLP); (ZG)
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail: (KSD); (KLP); (ZG)
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15
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Abstract
[This corrects the article DOI: 10.1371/journal.ppat.1009672.].
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16
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Sharon BM, Hulyalkar NV, Nguyen VH, Zimmern PE, Palmer KL, De Nisco NJ. Hybrid De Novo Genome Assembly for the Generation of Complete Genomes of Urinary Bacteria using Short- and Long-read Sequencing Technologies. J Vis Exp 2021. [PMID: 34487123 DOI: 10.3791/62872] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Complete genome sequences provide valuable data for the understanding of genetic diversity and unique colonization factors of urinary microbes. These data may include mobile genetic elements, such as plasmids and extrachromosomal phage, that contribute to the dissemination of antimicrobial resistance and further complicate treatment of urinary tract infection (UTI). In addition to providing fine resolution of genome structure, complete, closed genomes allow for the detailed comparative genomics and evolutionary analyses. The generation of complete genomes de novo has long been a challenging task due to limitations of available sequencing technology. Paired-end Next Generation Sequencing (NGS) produces high quality short reads often resulting in accurate but fragmented genome assemblies. On the contrary, Nanopore sequencing provides long reads of lower quality normally leading to error-prone complete assemblies. Such errors may hamper genome-wide association studies or provide misleading variant analysis results. Therefore, hybrid approaches combining both short and long reads have emerged as reliable methods to achieve highly accurate closed bacterial genomes. Reported herein is a comprehensive method for the culture of diverse urinary bacteria, species identification by 16S rRNA gene sequencing, extraction of genomic DNA (gDNA), and generation of short and long reads by NGS and Nanopore platforms, respectively. Additionally, this method describes a bioinformatic pipeline of quality control, assembly, and gene prediction algorithms for the generation of annotated complete genome sequences. Combination of bioinformatic tools enables the selection of high quality read data for hybrid genome assembly and downstream analysis. The streamlined approach for the hybrid de novo genome assembly described in this protocol may be adapted for the use in any culturable bacteria.
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Affiliation(s)
- Belle M Sharon
- Department of Biological Sciences, University of Texas at Dallas
| | - Neha V Hulyalkar
- Department of Biological Sciences, University of Texas at Dallas
| | - Vivian H Nguyen
- Department of Biological Sciences, University of Texas at Dallas
| | | | - Kelli L Palmer
- Department of Biological Sciences, University of Texas at Dallas
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17
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Affiliation(s)
- Dennise Palacios Araya
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Kelli L. Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
- * E-mail: (KLP); (BAD)
| | - Breck A. Duerkop
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail: (KLP); (BAD)
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18
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Shen WJ, Deshpande A, Hevener KE, Endres BT, Garey KW, Palmer KL, Hurdle JG. Constitutive expression of the cryptic vanGCd operon promotes vancomycin resistance in Clostridioides difficile clinical isolates. J Antimicrob Chemother 2021; 75:859-867. [PMID: 31873741 DOI: 10.1093/jac/dkz513] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/01/2019] [Accepted: 11/09/2019] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVES To describe, for the first time (to the best of our knowledge), the genetic mechanisms of vancomycin resistance in clinical isolates of Clostridioides difficile ribotype 027. METHODS Clinical isolates and laboratory mutants were analysed: genomically to identify resistance mutations; by transcriptional analysis of vanGCd, the vancomycin resistance operon encoding lipid II d-alanine-d-serine that is less bound by vancomycin than native lipid II d-alanine-d-alanine; by imaging of vancomycin binding to cell walls; and for changes in vancomycin bactericidal activity and autolysis. RESULTS Vancomycin-resistant laboratory mutants and clinical isolates acquired mutations to the vanSR two-component system that regulates vanGCd. The substitutions impaired VanSR's function, resulting in constitutive transcription of vanGCd. Resistance was reversed by silencing vanG, encoding d-alanine-d-serine ligase in the vanGCd operon. In resistant cells, vancomycin was less bound to the cell wall septum, the site where vancomycin interacts with lipid II. Vancomycin's bactericidal activity was reduced against clinical isolates and laboratory mutants (64 and ≥1024 mg/L, respectively) compared with WT strains (4 mg/L). Truncation of the potassium transporter TrkA occurred in laboratory mutants, which were refractory to autolysis, accounting for their survival in high drug concentrations. CONCLUSIONS Ribotype 027 evolved first-step resistance to vancomycin by constitutively expressing vanGCd, which is otherwise silent. Experimental evolutions and bactericidal assays show that ribotype 027 can acquire mutations to drastically enhance its tolerance to vancomycin. Thus, further epidemiological studies are warranted to examine the extent to which vancomycin resistance impacts clinical outcomes and the potential for these strains to evolve higher-level resistance, which would be devastating.
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Affiliation(s)
- Wan-Jou Shen
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Aditi Deshpande
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Kirk E Hevener
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN 38105, USA
| | - Bradley T Endres
- Department of Pharmacy Practice and Translational Research, College of Pharmacy, University of Houston, Houston, TX 77204, USA
| | - Kevin W Garey
- Department of Pharmacy Practice and Translational Research, College of Pharmacy, University of Houston, Houston, TX 77204, USA
| | - Kelli L Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Julian G Hurdle
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
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19
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Joyce LR, Guan Z, Palmer KL. Streptococcus pneumoniae, S. pyogenes and S. agalactiae membrane phospholipid remodelling in response to human serum. Microbiology (Reading) 2021; 167. [PMID: 33983874 PMCID: PMC8290102 DOI: 10.1099/mic.0.001048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Streptococcus pneumoniae, S. pyogenes (Group A Streptococcus; GAS) and S. agalactiae (Group B Streptococcus; GBS) are major aetiological agents of diseases in humans. The cellular membrane, a crucial site in host–pathogen interactions, is poorly characterized in streptococci. Moreover, little is known about whether or how environmental conditions influence their lipid compositions. Using normal phase liquid chromatography coupled with electrospray ionization MS, we characterized the phospholipids and glycolipids of S. pneumoniae, GAS and GBS in routine undefined laboratory medium, streptococcal defined medium and, in order to mimic the host environment, defined medium supplemented with human serum. In human serum-supplemented medium, all three streptococcal species synthesize phosphatidylcholine (PC), a zwitterionic phospholipid commonly found in eukaryotes but relatively rare in bacteria. We previously reported that S. pneumoniae utilizes the glycerophosphocholine (GPC) biosynthetic pathway to synthesize PC. Through substrate tracing experiments, we confirm that GAS and GBS scavenge lysoPC, a major metabolite in human serum, thereby using an abbreviated GPC pathway for PC biosynthesis. Furthermore, we found that plasmanyl-PC is uniquely present in the GBS membrane during growth with human serum, suggesting GBS possesses unusual membrane biochemical or biophysical properties. In summary, we report cellular lipid remodelling by the major pathogenic streptococci in response to metabolites present in human serum.
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Affiliation(s)
- Luke R Joyce
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Kelli L Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
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20
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Ping S, Mayorga-Reyes N, Price VJ, Onuoha M, Bhardwaj P, Rodrigues M, Owen J, Palacios Araya D, Akins RL, Palmer KL. Characterization of presumptive vancomycin-resistant enterococci recovered during infection control surveillance in Dallas, Texas, USA. Access Microbiol 2021; 3:000214. [PMID: 34151166 PMCID: PMC8209702 DOI: 10.1099/acmi.0.000214] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 02/24/2021] [Indexed: 11/18/2022] Open
Abstract
Enterococcus faecalis and E. faecium are Gram-positive bacteria that normally inhabit the human gastrointestinal tract. They are also opportunistic pathogens and can cause nosocomial infection outbreaks. To prevent the spread of nosocomial infections, hospitals may rely on screening methods to identify patients colonized with multidrug-resistant organisms including vancomycin-resistant enterococci (VRE). Spectra VRE agar (Remel) contains vancomycin and other medium components that select for VRE and phenotypically differentiate between E. faecalis and E. faecium by colony colour. We obtained 66 de-identified rectal swab cultures on Spectra VRE agar that were obtained during routine patient admission surveillance at a hospital system in Dallas, Texas, USA. We analysed 90 presumptive VRE from 61 of the Spectra VRE agar cultures using molecular and culture methods. Using ddl typing, 55 were found to be E. faecium and 32 were found to be E. faecalis . While most of the E. faecium were positive for the vanA gene by PCR (52 of 55 strains), few of the E. faecalis were positive for either vanA or vanB (five of 32 strains). The 27 E. faecalis vanA- and vanB-negative strains could not be recultured on Spectra VRE agar. Overall, we found that Spectra VRE agar performed robustly for the identification of vancomycin-resistant E. faecium , but presumptive false positives were obtained for vancomycin-resistant E. faecalis .
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Affiliation(s)
- Sara Ping
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Nancy Mayorga-Reyes
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Valerie J. Price
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Michelle Onuoha
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Pooja Bhardwaj
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Marinelle Rodrigues
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Jordan Owen
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Dennise Palacios Araya
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | | | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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21
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Jain SS, Schramm STJ, Siddiqui DA, Huo W, Palmer KL, Wilson TG, Rodrigues DC. Effects of multiple implantations of titanium healing abutments: Surface characteristics and microbial colonization. Dent Mater 2020; 36:e279-e291. [PMID: 32591158 PMCID: PMC7429256 DOI: 10.1016/j.dental.2020.05.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 04/06/2020] [Accepted: 05/24/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Very few studies have investigated dental implant components involved in the early stage of healing, especially the implant healing abutment (IHA), despite its vital role in soft tissue contouring and shaping after implant placement. Although these components are labelled by the manufacturer for "single-use only," it is a common clinical practice to clean, sterilize, and reuse them. METHODS In the present study, IHAs after single and multiple implantations were retrieved as per standard procedures, and biological material isolated from the surface was subjected to 16S rRNA sequence analysis. The microbiome analysis was followed by cleaning and sterilization in order to replicate clinical sterilization techniques. Following sterilization, retrievals were subjected to surface characterization with optical and scanning electron microscopy to investigate surface features, and electrochemical testing was performed to evaluate corrosion behavior. RESULTS The microbiota was comprised of early colonizers including Streptococcus species and secondary anaerobic colonizers such as Fusobacterium, Capnocytophaga, and Prevotella species. The surface analysis revealed that irrespective of the cleaning and sterilization techniques, the pristine, homogeneous surface of the new, unused IHAs could not be restored. Both single and multiple-use IHAs had severe surface changes including discoloration, major abrasions, biological contamination, and the IHA retrievals exhibited higher corrosion rate as compared to control specimens. SIGNIFICANCE Reusing IHAs multiple times may not be a prudent practice as the microbial colonization and surface changes caused by using this component multiple times may affect the performance of IHAs in soft tissue healing.
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Affiliation(s)
- Sanjana S Jain
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Sareda T J Schramm
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Danyal A Siddiqui
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Wenwen Huo
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Kelli L Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080, USA
| | | | - Danieli C Rodrigues
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA.
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22
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Neugent ML, Gadhvi J, Palmer KL, Zimmern PE, De Nisco NJ. Detection of Tissue-resident Bacteria in Bladder Biopsies by 16S rRNA Fluorescence In Situ Hybridization. J Vis Exp 2019. [PMID: 31680675 DOI: 10.3791/60458] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Visualization of the interaction of bacteria with host mucosal surfaces and tissues can provide valuable insight into mechanisms of pathogenesis. While visualization of bacterial pathogens in animal models of infection can rely on bacterial strains engineered to express fluorescent proteins such as GFP, visualization of bacteria within the mucosa of biopsies or tissue obtained from human patients requires an unbiased method. Here, we describe an efficient method for the detection of tissue-associated bacteria in human biopsy sections. This method utilizes fluorescent in situ hybridization (FISH) with a fluorescently labeled universal oligonucleotide probe for 16S rRNA to label tissue-associated bacteria within bladder biopsy sections acquired from patients suffering from recurrent urinary tract infection. Through use of a universal 16S rRNA probe, bacteria can be detected without prior knowledge of species, genera, or biochemical characteristics, such as lipopolysaccharide (LPS), that would be required for detection by immunofluorescence experiments. We describe a complete protocol for 16S rRNA FISH from biopsy fixation to imaging by confocal microscopy. This protocol can be adapted for use in almost any type of tissue and represents a powerful tool for the unbiased visualization of clinically-relevant bacterial-host interactions in patient tissue. Furthermore, using species or genera-specific probes, this protocol can be adapted for the detection of specific bacterial pathogens within patient tissue.
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Affiliation(s)
| | - Jashkaran Gadhvi
- Department of Biological Sciences, University of Texas at Dallas
| | - Kelli L Palmer
- Department of Biological Sciences, University of Texas at Dallas
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23
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Abstract
Cement-retained restorations on dental implants are a well-established method to replace missing teeth. However, undetected residual cement left during crown cementation procedures encourages microorganism growth, and it has been identified as a risk factor for peri-implant disease. Currently, there is no official guidance for dental cement selection, and the increasing variety of available compositions intensifies the complexity of the clinicians' decision process. The present study aimed to evaluate the in vitro host and bacterial cellular response to four different commercial dental cements as well as their effects on cement surface morphology. Disk specimens (n = 3) of bioceramic, zinc phosphate, resin-modified glass ionomer, and resin cements were exposed to host (murine pre-osteoblasts, human gingival fibroblasts, and undifferentiated human macrophages) and oral bacterial (Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguinis, and Aggregatibacter actinomycetemcomitans) cells. Results indicated that oral bacteria degraded the cement surface, but bacterial viability was not significantly affected by the presence of dental cement. Conversely, the biocompatibility and morphology of host cells were severely impacted by the cement composition. Only the bioceramic cement achieved >70% viability for all cell lines investigated. Within the limitations of this study, the results indicated the importance of considering the biological interactions of a dental cement composition during selection as it played a significant role in the host cellular response and the degree of surface degradation due to bacterial attack.
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Affiliation(s)
| | | | | | - Claudia C Biguetti
- Department of Biological Sciences, Bauru School of Dentistry, Bauru, São Paulo 17012, Brazil
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24
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De Nisco NJ, Neugent M, Mull J, Chen L, Kuprasertkul A, de Souza Santos M, Palmer KL, Zimmern P, Orth K. Direct Detection of Tissue-Resident Bacteria and Chronic Inflammation in the Bladder Wall of Postmenopausal Women with Recurrent Urinary Tract Infection. J Mol Biol 2019; 431:4368-4379. [PMID: 31002774 DOI: 10.1016/j.jmb.2019.04.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 04/05/2019] [Accepted: 04/05/2019] [Indexed: 02/02/2023]
Abstract
Urinary tract infections (UTIs) are the most commonly reported infections in adult women and have high rates of recurrence, especially in postmenopausal women. Recurrent UTI (RUTI) greatly reduces quality of life, places a significant burden on the healthcare system, and contributes to antimicrobial resistance. Because treatment of RUTI by long-term antibiotic therapy is often ineffective or poorly tolerated in elderly women, new therapies must be developed. The molecular basis of RUTI, especially in postmenopausal women, has remained unclear because modeling RUTI in mice is difficult, and human data are limited. Invasion of the urothelium and induction of host inflammation are hypothesized to be key mechanisms by which bacterial pathogens cause RUTI. To further our understanding of RUTI in humans, we performed a systematic analysis of urine and bladder biopsy samples from postmenopausal women undergoing cystoscopy with fulguration of trigonitis in the advanced management of antibiotic-refractory RUTI. We provide direct evidence that bacteria reside in the bladder wall of postmenopausal RUTI patients and that diverse bacterial species can be isolated from the bladder tissue. Histopathological scoring revealed significant edema and alterations of urothelial architecture in RUTI patient biopsies. Lymphocytes, including plasma B-cells, were detected within the mesenchyme, urothelium, and follicular aggregates in the majority of patients, indicating that the local adaptive immune response is active during human RUTI. These data provide conclusive evidence that bacteria invade the human urothelium and suggest that diverse bacterial species and the adaptive immune response play important roles in RUTI in humans.
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Affiliation(s)
- Nicole J De Nisco
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Michael Neugent
- Department of Biological Sciences, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Jason Mull
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Luming Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Amy Kuprasertkul
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marcela de Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kelli L Palmer
- Department of Biological Sciences, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Philippe Zimmern
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Abstract
CRISPR-Cas provides a barrier to horizontal gene transfer in prokaryotes. It was previously observed that functional CRISPR-Cas systems are absent from multidrug-resistant (MDR) Enterococcus faecalis, which only possess an orphan CRISPR locus, termed CRISPR2, lacking cas genes. Here, we investigate how the interplay between CRISPR-Cas genome defense and antibiotic selection for mobile genetic elements shapes in vitro E. faecalis populations. We demonstrate that CRISPR2 can be reactivated for genome defense in MDR strains. Interestingly, we observe that E. faecalis transiently maintains CRISPR targets despite active CRISPR-Cas systems. Subsequently, if selection for the CRISPR target is present, toxic CRISPR spacers are lost over time, while in the absence of selection, CRISPR targets are lost over time. We find that forced maintenance of CRISPR targets induces a fitness cost that can be exploited to alter heterogeneous E. faecalis populations.
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Affiliation(s)
- Karthik Hullahalli
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, United States
| | - Marinelle Rodrigues
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, United States
| | - Kelli L Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, United States
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26
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Akins RL, Barber KE, Palmer KL. Pronounced heterogeneity observed in high-level daptomycin-resistant viridans group streptococci. J Glob Antimicrob Resist 2016; 7:159-166. [PMID: 27835845 DOI: 10.1016/j.jgar.2016.09.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 09/08/2016] [Accepted: 09/10/2016] [Indexed: 11/26/2022] Open
Abstract
Viridans group streptococci (VGS) have demonstrated high-level daptomycin resistance (HLDR) upon daptomycin exposure. This study evaluated the extent of heterogeneity and whether dose escalation or combination therapy could prevent resistance development. Five VGS strains (daptomycin MICs 0.25-2mg/L) were evaluated. In vitro models utilised simulated daptomycin dosages of 4, 6, 8 and 12mg/kg with estimated fCmax of 4.1, 6.6, 8.6 and 12.9mg/L, respectively. Time-kill studies included fCmax simulations of daptomycin alone or combined with ceftriaxone, gentamicin, linezolid, rifampicin or vancomycin. Population analyses were performed on daptomycin-containing and non-containing agar plates. Extreme heterogeneity was observed in four strains with daptomycin population MICs 4-512-fold higher than broth microdilution. Whilst Streptococcus gordonii 1649 did not consistently develop HLDR, its population MIC was above the established daptomycin breakpoint. In vitro modelling demonstrated initial kill by daptomycin in all strains within 8h, with substantial re-growth by 24h despite increasing daptomycin. Daptomycin kill curves also displayed resistance development by 24h. However, synergy or additivity was noted for most regimens and strains. Synergy was most notable with daptomycin plus linezolid or rifampicin. Overall, daptomycin plus ceftriaxone or gentamicin were the most potent regimens. Gentamicin or rifampicin with daptomycin were least additive. For combination regimens with colonies isolated at 24h, HLDR was reduced 16-64-fold (MICs 4-16mg/L). Daptomycin monotherapy for VGS led to rapid development of HLDR likely due to extreme heterogeneity. Combination therapy suppressed or minimised the degree of resistance although the mechanism remains unknown.
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Affiliation(s)
- Ronda L Akins
- Methodist Charlton Medical Center, Dallas, TX, USA; University of Texas at Dallas, Richardson, TX, USA; Louisiana State University Health Sciences Center-Shreveport, School of Medicine, Shreveport, LA, USA.
| | - Katie E Barber
- Louisiana State University Health Sciences Center-Shreveport, Department of Pharmacy, Shreveport, LA, USA
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Gindri IM, Palmer KL, Siddiqui DA, Aghyarian S, Frizzo CP, Martins MAP, Rodrigues DC. Evaluation of mammalian and bacterial cell activity on titanium surface coated with dicationic imidazolium-based ionic liquids. RSC Adv 2016. [DOI: 10.1039/c6ra01003b] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
This work presents a new strategy to protect titanium surfaces against bacterial colonization and biofilm formation using dicationic imidazolium-based ionic liquid coatings.
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Affiliation(s)
| | - Kelli L. Palmer
- Department of Biological Sciences
- University of Texas at Dallas
- Richardson
- USA
| | | | - Shant Aghyarian
- Department of Bioengineering
- University of Texas at Dallas
- Richardson
- USA
| | - Clarissa P. Frizzo
- Department of Chemistry
- Universidade Federal de Santa Maria
- Santa Maria
- Brazil–97105-900
| | - Marcos A. P. Martins
- Department of Chemistry
- Universidade Federal de Santa Maria
- Santa Maria
- Brazil–97105-900
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Hullahalli K, Rodrigues M, Schmidt BD, Li X, Bhardwaj P, Palmer KL. Comparative Analysis of the Orphan CRISPR2 Locus in 242 Enterococcus faecalis Strains. PLoS One 2015; 10:e0138890. [PMID: 26398194 PMCID: PMC4580645 DOI: 10.1371/journal.pone.0138890] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/04/2015] [Indexed: 12/18/2022] Open
Abstract
Clustered, Regularly Interspaced Short Palindromic Repeats and their associated Cas proteins (CRISPR-Cas) provide prokaryotes with a mechanism for defense against mobile genetic elements (MGEs). A CRISPR locus is a molecular memory of MGE encounters. It contains an array of short sequences, called spacers, that generally have sequence identity to MGEs. Three different CRISPR loci have been identified among strains of the opportunistic pathogen Enterococcus faecalis. CRISPR1 and CRISPR3 are associated with the cas genes necessary for blocking MGEs, but these loci are present in only a subset of E. faecalis strains. The orphan CRISPR2 lacks cas genes and is ubiquitous in E. faecalis, although its spacer content varies from strain to strain. Because CRISPR2 is a variable locus occurring in all E. faecalis, comparative analysis of CRISPR2 sequences may provide information about the clonality of E. faecalis strains. We examined CRISPR2 sequences from 228 E. faecalis genomes in relationship to subspecies phylogenetic lineages (sequence types; STs) determined by multilocus sequence typing (MLST), and to a genome phylogeny generated for a representative 71 genomes. We found that specific CRISPR2 sequences are associated with specific STs and with specific branches on the genome tree. To explore possible applications of CRISPR2 analysis, we evaluated 14 E. faecalis bloodstream isolates using CRISPR2 analysis and MLST. CRISPR2 analysis identified two groups of clonal strains among the 14 isolates, an assessment that was confirmed by MLST. CRISPR2 analysis was also used to accurately predict the ST of a subset of isolates. We conclude that CRISPR2 analysis, while not a replacement for MLST, is an inexpensive method to assess clonality among E. faecalis isolates, and can be used in conjunction with MLST to identify recombination events occurring between STs.
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Affiliation(s)
- Karthik Hullahalli
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
| | - Marinelle Rodrigues
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
| | - Brendan D. Schmidt
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
| | - Xiang Li
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
| | - Pooja Bhardwaj
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, United States of America
- * E-mail:
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Sridhar S, Wilson TG, Palmer KL, Valderrama P, Mathew MT, Prasad S, Jacobs M, Gindri IM, Rodrigues DC. In Vitro Investigation of the Effect of Oral Bacteria in the Surface Oxidation of Dental Implants. Clin Implant Dent Relat Res 2015; 17 Suppl 2:e562-75. [DOI: 10.1111/cid.12285] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Kelli L. Palmer
- Department of Molecular and Cell Biology; University of Texas at Dallas; Richardson TX USA
| | | | - Mathew T. Mathew
- Section of Tribology; Department of Orthopedic Surgery; Rush University Medical Center; Chicago IL USA
| | - Shalini Prasad
- Department of Bioengineering; University of Texas at Dallas; Richardson TX USA
| | - Michael Jacobs
- Department of Bioengineering; University of Texas at Dallas; Richardson TX USA
| | - Izabelle M. Gindri
- Department of Bioengineering; University of Texas at Dallas; Richardson TX USA
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Gindri IM, Siddiqui DA, Bhardwaj P, Rodriguez LC, Palmer KL, Frizzo CP, Martins MAP, Rodrigues DC. Dicationic imidazolium-based ionic liquids: a new strategy for non-toxic and antimicrobial materials. RSC Adv 2014. [DOI: 10.1039/c4ra09906k] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dicationic imidazolium-based ILs: a potent strategy for applications requiring non-toxic materials with antimicrobial activity.
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Affiliation(s)
- Izabelle M. Gindri
- Department of Bioengineering
- University of Texas at Dallas
- Richardson, USA
| | - Danyal A. Siddiqui
- Department of Bioengineering
- University of Texas at Dallas
- Richardson, USA
| | - Pooja Bhardwaj
- Department of Molecular and Cell Biology
- University of Texas at Dallas
- Richardson, USA
| | - Lucas C. Rodriguez
- Department of Bioengineering
- University of Texas at Dallas
- Richardson, USA
| | - Kelli L. Palmer
- Department of Molecular and Cell Biology
- University of Texas at Dallas
- Richardson, USA
| | - Clarissa P. Frizzo
- Department of Chemistry (NUQUIMHE)
- Universidade Federal de Santa Maria
- Santa Maria, Brazil
| | - Marcos A. P. Martins
- Department of Chemistry (NUQUIMHE)
- Universidade Federal de Santa Maria
- Santa Maria, Brazil
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31
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Teixeira N, Varahan S, Gorman MJ, Palmer KL, Zaidman-Remy A, Yokohata R, Nakayama J, Hancock LE, Jacinto A, Gilmore MS, de Fátima Silva Lopes M. Drosophila host model reveals new enterococcus faecalis quorum-sensing associated virulence factors. PLoS One 2013; 8:e64740. [PMID: 23734216 PMCID: PMC3667150 DOI: 10.1371/journal.pone.0064740] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 04/17/2013] [Indexed: 01/30/2023] Open
Abstract
Enterococcus faecalis V583 is a vancomycin-resistant clinical isolate which belongs to the hospital-adapted clade, CC2. This strain harbours several factors that have been associated with virulence, including the fsr quorum-sensing regulatory system that is known to control the expression of GelE and SprE proteases. To discriminate between genes directly regulated by Fsr, and those indirectly regulated as the result of protease expression or activity, we compared gene expression in isogenic mutants of V583 variously defective in either Fsr quorum sensing or protease expression. Quorum sensing was artificially induced by addition of the quorum signal, GBAP, exogenously in a controlled manner. The Fsr regulon was found to be restricted to five genes, gelE, sprE, ef1097, ef1351 and ef1352. Twelve additional genes were found to be dependent on the presence of GBAP-induced proteases. Induction of GelE and SprE by GBAP via Fsr resulted in accumulation of mRNA encoding lrgAB, and this induction was found to be lytRS dependent. Drosophila infection was used to discern varying levels of toxicity stemming from mutations in the fsr quorum regulatory system and the genes that it regulates, highlighting the contribution of LrgAB and bacteriocin EF1097 to infection toxicity. A contribution of SprE to infection toxicity was also detected. This work brought to light new players in E. faecalis success as a pathogen and paves the way for future studies on host tolerance mechanisms to infections caused by this important nosocomial pathogen.
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Affiliation(s)
- Neuza Teixeira
- ITQB Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Departments of Ophthalmology, and Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
- CEDOC Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Sriram Varahan
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Matthew J. Gorman
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Kelli L. Palmer
- Departments of Ophthalmology, and Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anna Zaidman-Remy
- CEDOC Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Ryoji Yokohata
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Jiro Nakayama
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Lynn E. Hancock
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - António Jacinto
- CEDOC Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Michael S. Gilmore
- Departments of Ophthalmology, and Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Maria de Fátima Silva Lopes
- ITQB Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- IBET Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- * E-mail:
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32
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Affiliation(s)
- Kelli L Palmer
- Section of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX 78712, USA.
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33
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Palmer KL, Kos VN, Gilmore MS. Horizontal gene transfer and the genomics of enterococcal antibiotic resistance. Curr Opin Microbiol 2010; 13:632-9. [PMID: 20837397 DOI: 10.1016/j.mib.2010.08.004] [Citation(s) in RCA: 187] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 08/20/2010] [Indexed: 10/19/2022]
Abstract
Enterococci are Gram-positive bacteria that normally colonize gastrointestinal tracts of humans and animals. They are of growing concern because of their ability to cause antibiotic resistant hospital infections. Antibiotic resistance has been acquired, and has disseminated throughout enterococci, via horizontal transfer of mobile genetic elements. This transmission has been mediated mainly by conjugative plasmids of the pheromone-responsive and broad host range incompatibility group 18 type. Genome sequencing is revealing the extent of diversity of these and other mobile elements in enterococci, as well as the extent of recombination and rearrangement resulting in new phenotypes. Pheromone-responsive plasmids were recently shown to promote genome plasticity in antibiotic resistant Enterococcus faecalis, and their involvement has been implicated in E. faecium as well. Further, incompatibility group 18 plasmids have recently played an important role in mediating transfer of vancomycin resistance from enterococci to methicillin-resistant strains of S. aureus.
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Affiliation(s)
- Kelli L Palmer
- Departments of Ophthalmology, and Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA, USA
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Abstract
The sputum (mucus) layer of the cystic fibrosis (CF) lung is a complex substrate that provides Pseudomonas aeruginosa with carbon and energy to support high-density growth during chronic colonization. Unfortunately, the CF lung sputum layer has been difficult to mimic in animal models of CF disease, and mechanistic studies of P. aeruginosa physiology during growth in CF sputum are hampered by its complexity. In this study, we performed chromatographic and enzymatic analyses of CF sputum to develop a defined, synthetic CF sputum medium (SCFM) that mimics the nutritional composition of CF sputum. Importantly, P. aeruginosa displays similar phenotypes during growth in CF sputum and in SCFM, including similar growth rates, gene expression profiles, carbon substrate preferences, and cell-cell signaling profiles. Using SCFM, we provide evidence that aromatic amino acids serve as nutritional cues that influence cell-cell signaling and antimicrobial activity of P. aeruginosa during growth in CF sputum.
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Affiliation(s)
- Kelli L Palmer
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, 1 University Station, A5000, Austin, TX 78712, USA
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Palmer KL, Brown SA, Whiteley M. Membrane-bound nitrate reductase is required for anaerobic growth in cystic fibrosis sputum. J Bacteriol 2007; 189:4449-55. [PMID: 17400735 PMCID: PMC1913347 DOI: 10.1128/jb.00162-07] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Accepted: 03/22/2007] [Indexed: 11/20/2022] Open
Abstract
The autosomal recessive disorder cystic fibrosis (CF) affects approximately 70,000 people worldwide and is characterized by chronic bacterial lung infections with the opportunistic pathogen Pseudomonas aeruginosa. To form a chronic CF lung infection, P. aeruginosa must grow and proliferate within the CF lung, and the highly viscous sputum within the CF lung provides a likely growth substrate. Recent evidence indicates that anaerobic microenvironments may be present in the CF lung sputum layer. Since anaerobic growth significantly enhances P. aeruginosa biofilm formation and antibiotic resistance, it is important to examine P. aeruginosa physiology and metabolism in anaerobic environments. Measurement of nitrate levels revealed that CF sputum contains sufficient nitrate to support significant P. aeruginosa growth anaerobically, and mutational analysis revealed that the membrane-bound nitrate reductase is essential for P. aeruginosa anaerobic growth in an in vitro CF sputum medium. In addition, expression of genes coding for the membrane-bound nitrate reductase complex is responsive to CF sputum nitrate levels. These findings suggest that the membrane-bound nitrate reductase is critical for P. aeruginosa anaerobic growth with nitrate in the CF lung.
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Affiliation(s)
- Kelli L Palmer
- Section of Molecular Genetics and Microbiology, The University of Texas at Austin, Austin, TX 78712, USA
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Abstract
The opportunistic human pathogen Pseudomonas aeruginosa causes persistent airway infections in patients with cystic fibrosis (CF). To establish these chronic infections, P. aeruginosa must grow and proliferate within the highly viscous sputum in the lungs of CF patients. In this study, we used Affymetrix GeneChip microarrays to investigate the physiology of P. aeruginosa grown using CF sputum as the sole source of carbon and energy. Our results indicate that CF sputum readily supports high-density P. aeruginosa growth. Furthermore, multiple signals, which reduce swimming motility and prematurely activate the Pseudomonas quinolone signal cell-to-cell signaling cascade in P. aeruginosa, are present in CF sputum. P. aeruginosa factors critical for lysis of the common CF lung inhabitant Staphylococcus aureus were also induced in CF sputum and increased the competitiveness of P. aeruginosa during polymicrobial growth in CF sputum.
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Affiliation(s)
- Kelli L Palmer
- Department of Periodontics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Al-Tawfiq JA, Palmer KL, Chen CY, Haley JC, Katz BP, Hood AF, Spinola SM. Experimental infection of human volunteers with Haemophilus ducreyi does not confer protection against subsequent challenge. J Infect Dis 1999; 179:1283-7. [PMID: 10191238 DOI: 10.1086/314732] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Two groups of human volunteers were inoculated with 2 doses of live Haemophilus ducreyi 35000HP. The reinfection group consisted of 7 subjects who previously had participated in experimental infection with 35000HP to the pustular stage of disease. The control group consisted of 7 naive subjects. Papules developed at 92.8% (95% confidence interval [CI], 66.1%-99.8%) of sites inoculated with live bacteria, in the reinfection group, and at 85.7% (95% CI, 57.2%-98. 2%) of sites in the control group. Sixty-nine percent (95% CI, 36. 8%-90.9%) of papules evolved into pustules in the reinfection group, compared with 41% (95% CI, 15.2%-72.3%) in the control group. The recovery rates of H. ducreyi from surface cultures and the histopathology of biopsies obtained from both groups were similar. Thus, experimental infection to the pustular stage of disease does not provide protective immunity against subsequent challenge.
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Affiliation(s)
- J A Al-Tawfiq
- Department of Medicine,Division of Infectious Diseases, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Palmer KL, Schnizlein-Bick CT, Orazi A, John K, Chen CY, Hood AF, Spinola SM. The immune response to Haemophilus ducreyi resembles a delayed-type hypersensitivity reaction throughout experimental infection of human subjects. J Infect Dis 1998; 178:1688-97. [PMID: 9815221 DOI: 10.1086/314489] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Previous work in 3 subjects infected for 2 weeks indicated that experimental infection with Haemophilus ducreyi recruits CD4 cells to the skin at the pustular stage of disease. In order to describe the kinetics of the host response, 23 subjects were infected at 2 sites with a standardized dose of H. ducreyi. Subjects were biopsied 1 or 4 days after inoculation or when they developed a painful pustular lesion (days 7-14). Papules and pustules contained a predominant T cell infiltrate that consisted of CD45RO and CD4 cells of the alpha beta lineage. Both papules and pustules contained mixed or T helper 1 type cytokine mRNA and interleukin-8 and tumor necrosis factor-alpha mRNA. Although the subjects had no history of chancroid, their immune responses resembled delayed-type hypersensitivity reactions that occurred within 24 h of inoculation and persisted throughout the course of experimental infection.
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Affiliation(s)
- K L Palmer
- Departments of Medicine, Microbiology, and Immunology, Indiana University, Indianapolis, IN 46202, USA
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Palmer KL, Thornton AC, Fortney KR, Hood AF, Munson RS, Spinola SM. Evaluation of an isogenic hemolysin-deficient mutant in the human model of Haemophilus ducreyi infection. J Infect Dis 1998; 178:191-9. [PMID: 9652440 DOI: 10.1086/515617] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Haemophilus ducreyi causes the genital ulcerative disease chancroid. One putative virulence factor of H. ducreyi is a pore-forming hemolysin that displays toxicity against human fibroblasts and keratinocytes. In order to test the role of the hemolysin in pathogenesis, an isogenic hemolysin-deficient mutant was constructed, designated 35000HP-RSM1. The lipooligosaccharide, outer membrane protein patterns, and growth attributes of 35000HP-RSM1 were identical to its parent, 35000HP. Human subjects were challenged on the upper arm with the isogenic isolates in a double-blinded, randomized, escalating dose-response study. Pustules developed at a similar rate at sites inoculated with the mutant or parent. The cellular infiltrate and bacterial load in lesions were also similar. These results indicate the hemolysin does not play a role in pustule formation. Due to the limitations of this model, the role of the hemolysin at later stages of infection could not be determined.
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Affiliation(s)
- K L Palmer
- Department of Medicine, Indiana University School of Medicine, Indianapolis 46202, USA
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Gibson BW, Campagnari AA, Melaugh W, Phillips NJ, Apicella MA, Grass S, Wang J, Palmer KL, Munson RS. Characterization of a transposon Tn916-generated mutant of Haemophilus ducreyi 35000 defective in lipooligosaccharide biosynthesis. J Bacteriol 1997; 179:5062-71. [PMID: 9260947 PMCID: PMC179363 DOI: 10.1128/jb.179.16.5062-5071.1997] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
To define the role of the surface lipooligosaccharide (LOS) of Haemophilus ducreyi in the pathogenesis of chancroid, Tn916 mutants of H. ducreyi 35000 defective in expression of the murine monoclonal antibody (MAb) 3F11 epitope on H. ducreyi LOS were identified by immunologic screening. One mutant, designated 1381, has an LOS which lacks the MAb 3F11 epitope and migrates with an increased mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gene disrupted by the Tn916 element in strain 1381 was identified by cloning the sequences flanking the Tn916 element. The sequences were then used to probe a lambda DASHII genomic library. In strain 1381, Tn916 interrupts a gene which encodes an open reading frame (ORF) with an Mr of 40,246. This ORF has homology to the product of the rfaK gene of Escherichia coli. The major LOS glycoform produced by strain 1381 was analyzed by using a combination of mass spectrometry, linkage and composition analysis, and 1H nuclear magnetic resonance spectroscopy. The major LOS species was found to terminate in a single glucose attached to the heptose (L-glycero-D-manno-heptose, or Hep) trisaccharide core. In the wild-type strain 35000, glucose serves as the acceptor for the addition of the D-glycero-D-manno-heptose (or DDHep), which extends to form the mature branch of the H. ducreyi LOS. This mature oligosaccharide is in turn partially capped by the addition of sialic acid (NeuAc), i.e., NeuAc2 alpha-->3Gal beta1-->4GlcNAc beta1-->3Gal beta1-->4DDHep alpha1-->6Glc beta1 (W. Melaugh et al., Biochemistry 33:13070-13078, 1994). Since this LOS terminates prior to the addition of the branch DD-heptose, this gene is likely to encode the D-glycero-D-manno-heptosyltransferase. Strain 1381 exhibits a significant reduction in adherence to and invasion of primary human keratinocytes. This defect was complemented by the cloned heptosyltransferase gene, indicating that the terminal portion of the LOS oligosaccharide plays an important role in adherence to human keratinocytes.
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Affiliation(s)
- B W Gibson
- Department of Pharmaceutical Chemistry, University of California, San Francisco 94143-0446, USA
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Palmer KL, Goldman WE, Munson RS. An isogenic haemolysin-deficient mutant of Haemophilus ducreyi lacks the ability to produce cytopathic effects on human foreskin fibroblasts. Mol Microbiol 1996; 21:13-9. [PMID: 8843430 DOI: 10.1046/j.1365-2958.1996.00615.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The haemolysin of Haemophilus ducreyi is the newest member of the Proteus/Serratia family of pore-forming toxins. In order to assess the role of the haemolysin in virulence, we constructed an isogenic haemolysin-deficient mutant of H. ducreyi strain 35000 This strain, designated 35000-3, lacks detectable haemolytic activity. We tested H. ducreyi strains 35000 and 35000-3 for their cytopathic activity against human foreskin fibroblasts (HFFs). We observed strong cytopathic activity when strain 35000 was co-cultured with HFFs. In contrast, cytopathic activity was not observed when strain 35000-3 was co-cultured with HFF cells. We also analysed the isogenic pair of H. ducreyi strains for cytopathic activity against HeLa cells and the keratinocyte cell line HaCaT. Strains 35000 and 35000-3 were strongly cytotoxic when co-cultured with HeLa cells. HaCaT monolayers were slightly damaged by cocultivation with strain 35000-3 but this damage was much less than that observed when HaCaT cells were cocultured with strain 35000. These results indicate that the H. ducreyi haemolysin is responsible for the previously observed cytotoxic activity against HFF cells and is partially responsible for the activity observed with HaCaT cells. The haemolysin, however, is not responsible for the activity observed with HeLa cells.
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Affiliation(s)
- K L Palmer
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Abstract
We previously identified a heat- and protease-labile haemolytic activity expressed by Haemophilus ducreyi. In order to characterize the haemolysin at the molecular level, genomic DNA from H. ducreyi was probed with haemolysin genes from other Gram-negative organisms. The haemolysin genes of Proteus mirabilis hybridized to H. ducreyi DNA suggesting that the haemolysin of H. ducreyi is related to the Proteus/Serratia pore-forming family of haemolysins. Tn916 mutagenesis was employed to isolate haemolysin-deficient mutants. Approximately 5000 Tn916 transposon mutants were screened for the loss of haemolytic activity and two mutants were identified. One mutant, designated 35,000-1, was further characterized. Sequences flanking the Tn916 element in strain 35,000-1 were employed to identify clones from a lambda DASHII library of H. ducreyi strain 35,000 DNA. A 13 kb insert from one lambda clone was selected for further study. This 13 kb fragment was able to both confer haemolytic activity to Escherichia coli and complement the haemolysin deficiency in strain 35,000-1. The haemolysin gene cluster was cloned from this 13 kb insert and two genes, designated hhdA and hhdB, were identified. The derived amino acid sequence of these genes demonstrated homology to the haemolysin and activation/secretion proteins of P. mirabilis and Serratia marcescens.
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Affiliation(s)
- K L Palmer
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, Seattle 98195, USA
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Abstract
Haemophilus ducreyi is the causative agent of the sexually transmitted disease chancroid. We have identified a hemolytic activity expressed by H. ducreyi. This activity is most readily detected when horse erythrocytes are used as a target; however, low levels of activity can be detected with sheep, human, or rabbit erythrocyte targets. The activity is heat labile and protease sensitive.
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Affiliation(s)
- K L Palmer
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
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Khattri R, Hansen B, Nichols TC, Palmer KL, Gilman-Sachs A, Baum LL. Anti-C-reactive protein inhibits cytoskeletal rearrangement without altering calcium influx in natural killer cell activation. Cell Immunol 1994; 155:457-75. [PMID: 8181076 DOI: 10.1006/cimm.1994.1138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
C-reactive protein (CRP), an acute phase protein in human serum, is present on large granular lymphocytes (LGL). Anti-CRP inhibits natural killer (NK) cell-mediated lysis. Our current study shows that anti-CRP also inhibits antibody-dependent cell-mediated cytotoxicity (ADCC) of LGL. Calcium influx and protein kinase C (PKC) activation are the early signal transduction events in NK activation. In the conjugates formed between LGL and targets (NK or ADCC), 75-90% of LGL respond with a calcium influx. Addition of anti-CRP had no effect on the percentage of LGL which respond to target cell binding or on the magnitude of the calcium response of LGL. This was true for both NK and ADCC effector cells. Crosslinking anti-CRP with a secondary antibody did not alter this result. Next, the effect of PMA, a PKC activator, and calcium ionophore, A23187, on anti-CRP-mediated inhibition of cytotoxicity were studied. PMA alone reversed most of the inhibition of lysis seen with anti-CRP. Based on previous observations that anti-CRP inhibited target cell-stimulated release of lytic factors, the effect of anti-CRP on release of lytic factors stimulated by PMA and calcium ionophore was evaluated. Anti-CRP blocked the release of lytic factors stimulated by PMA and ionophore. Release of lytic factors involves the rearrangement of cytoskeletal element of NK cell toward the target cell. The effect of anti-CRP on cytoskeletal reorganization was studied. In conjugates formed between effector and target cells, the polarization of cytoskeleton at the contact site of NK and target cell was significantly reduced in the presence of anti-CRP. Although anti-CRP inhibits both ADCC and NK lytic mechanisms, it does not alter target cell-induced Ca2+ influx. CRP interacts with the secretory mechanisms involved in granule exocytosis since anti-CRP inhibits the cytoskeletal polarization and the release of lytic factors and PMA might reverse anti-CRP-mediated inhibition by activating alternative mechanisms of cytotoxicity in effectors.
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Affiliation(s)
- R Khattri
- Department of Microbiology and Immunology, University of Health Sciences/The Chicago Medical School, Illinois 60064
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Abstract
A murine monoclonal antibody (mAb), designated 3H12, reacts with a surface-exposed conformational epitope on the pilus of non-typable Haemophilus influenzae strain M37. This antibody does not recognize the related pilus from H. influenzae type b, strain MinnA. Although mAb 3H12 does not recognize strain M37 pilin on Western blots, mAb 3H12 recognizes the recombinant M37 pilin protein expressed by Escherichia coli. In order to map the epitope recognized by mAb 3H12, we constructed a series of chimaeric genes. The chimaeric genes were expressed in E. coli and the chimaeric proteins characterized with respect to their reactivity with mAb 3H12. Residues between 37 and 100 of the M37 pilin protein are essential for the expression of the mAb 3H12 epitope. Residues in the carboxyl half of the M37 protein enhance the reactivity of mAb 3H12 when expressed in the presence of residues 37-100. Construction of chimaeric genes may provide a general methodology for mapping of conformational epitopes expressed by one of a related pair of proteins.
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Affiliation(s)
- K L Palmer
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri
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Affiliation(s)
- K C Huddleston
- Children's Hospital of the King's Daughters, Norfolk, Virginia
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Siddiqui WA, Tam LQ, Kan SC, Kramer KJ, Case SE, Palmer KL, Yamaga KM, Hui GS. Induction of protective immunity to monoclonal-antibody-defined Plasmodium falciparum antigens requires strong adjuvant in Aotus monkeys. Infect Immun 1986; 52:314-8. [PMID: 3514459 PMCID: PMC262236 DOI: 10.1128/iai.52.1.314-318.1986] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Monoclonal antibodies to the major Plasmodium falciparum merozoite surface coat and rhoptry antigens were produced. A combination of the affinity-purified polypeptides with Freund complete adjuvant which was given three times completely protected an Aotus lemurinus azure (karotype VI) monkey against homologous challenge; however, immunization with the same polypeptides with a muramyl dipeptide derivative [MDP-Lys(L18)] did not protect a second Aotus monkey, even though comparable high antibody titers were induced.
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Abstract
Plasma from units of human blood collected in CPDA-1 preservative were compared with human serum in cultures of Plasmodium falciparum. No significant differences in parasite growth and multiplication were seen between cultures containing serum or plasma. The wider availability of plasma makes it an attractive alternative to serum, especially in large scale cultures.
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Abstract
Cultures of Plasmodium falciparum with parasitemias of 3-5% were exposed to 4 mM colchicine for 24 hours. Synchrony was observed 48 hours after treatment, and the cultures remained synchronous for more than two replicative cycles. The percentage of ring stage parasites reached peaks of over 90% at 72 and 120 hours. The percentage of schizonts reached a peak of 70% at 144 hours. Parasitemias in both colchicine-treated and untreated control cultures reached peaks of over 20% 120 hours after colchicine treatment.
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Palmer KL, Hui GS, Siddiqui WA, Palmer EL. A large-scale in vitro production system for Plasmodium falciparum. J Parasitol 1982; 68:1180-3. [PMID: 6757400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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