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Leite DPDSBM, Barbosa IC, da Silva RA, Fernandes PR, Abad ACA, da Silva JG, Mota RA, Porto TS. Occurrence of antimicrobial-resistant Staphylococcus aureus in a Brazilian veterinary hospital environment. Braz J Microbiol 2023; 54:2393-2401. [PMID: 37407882 PMCID: PMC10485224 DOI: 10.1007/s42770-023-01035-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 06/07/2023] [Indexed: 07/07/2023] Open
Abstract
Antimicrobial resistance is a threat to public health. The emergence of antibiotic-resistant Staphylococcus aureus represents a priority for the implementation of preventive measures. The objective was to isolate S. aureus in humans, animals, and animal health care environment, and to characterize the genotypic and phenotypic profile of antimicrobial resistance in these isolates. We isolated S. aureus from staff, animals, and environment of a veterinary hospital, and identified their antimicrobial resistance profiles. Samples were collected from 20 humans, 13 animals, 14 surfaces, 8 mobile phones, and 7 veterinarians' stethoscopes by using sterile swabs. S. aureus was isolated by culturing on mannitol salt agar and preliminary identification was done by Gram staining and catalase test. Subsequently, a polymerase chain reaction was performed for species confirmation and investigating their antimicrobial-resistant genotypic profiles. Phenotypic profiles of resistant isolates were determined using the disk-diffusion technique. Ten S. aureus isolates were recovered from 5/20 humans (25%), it was also recovered from 2/13 animals (15.38%), including 1 dog and 1 cat, and from 1/14 of surfaces (7.14%). The oxacillin-susceptible mecA-positive Staphylococcus aureus phenotype was identified in a feline. Most of the isolates carried at least two resistance genes of different antimicrobial classes, with 90% (9/10) presenting the gene blaZ, with 10% (1/10) presenting the gene mecA, 20% (2/10) presenting tet38, 10% (1/10) presenting tetM, 90% (9/10) presenting norA, 50% (5/10) presenting norC, 10% (1/10) presenting ermA, and 60% (6/10) presenting ermB. In antibiograms, resistance to penicillin was identified in all the isolates, resistance to erythromycin was identified in 80% (8/10), and all the isolate's resistance to erythromycin presented erythromycin-induced resistance to clindamycin. Antimicrobial resistance in the veterinary hospital requires attention due to the risk of interspecies transmission, gene transfer between bacteria that colonize companion animals and humans and, can make antimicrobial therapy difficult.
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Affiliation(s)
- Denny Parente de Sá Barreto Maia Leite
- Department of Veterinary Medicine, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
| | - Iago Carvalho Barbosa
- Department of Veterinary Medicine, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
| | - Renato Amorim da Silva
- Department of Veterinary Medicine, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
| | - Pollyanne Raysa Fernandes
- Department of Veterinary Medicine, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
| | - Atzel Candido Acosta Abad
- Department of Veterinary Medicine, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
| | - José Givanildo da Silva
- Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechnics, Federal University of Bahia (UFBA), Salvador, Bahia, Brazil
| | - Rinaldo Aparecido Mota
- Department of Veterinary Medicine, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil.
| | - Tatiana Souza Porto
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil.
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Haag AF, Liljeroos L, Donato P, Pozzi C, Brignoli T, Bottomley MJ, Bagnoli F, Delany I. In Vivo Gene Expression Profiling of Staphylococcus aureus during Infection Informs Design of Stemless Leukocidins LukE and -D as Detoxified Vaccine Candidates. Microbiol Spectr 2023; 11:e0257422. [PMID: 36688711 PMCID: PMC9927290 DOI: 10.1128/spectrum.02574-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 01/02/2023] [Indexed: 01/24/2023] Open
Abstract
Staphylococcus aureus is a clinically important bacterial pathogen that has become resistant to treatment with most routinely used antibiotics. Alternative strategies, such as vaccination and phage therapy, are therefore actively being investigated to prevent or combat staphylococcal infections. Vaccination requires that vaccine targets are expressed at sufficient quantities during infection so that they can be targeted by the host's immune system. While our knowledge of in vitro expression levels of putative vaccine candidates is comprehensive, crucial in vivo expression data are scarce and promising vaccine candidates during in vitro assessment often prove ineffective in preventing S. aureus infection. Here, we show how a newly developed high-throughput quantitative reverse transcription-PCR (qRT-PCR) assay monitoring the expression of 84 staphylococcal genes encoding mostly virulence factors can inform the selection and design of effective vaccine candidates against staphylococcal infections. We show that this assay can accurately quantify mRNA expression levels of these genes in several host organs relying only on very limited amounts of bacterial mRNA in each sample. We selected two highly expressed genes, lukE and lukD, encoding pore-forming leukotoxins, to inform the design of detoxified recombinant proteins and showed that immunization with recombinant genetically detoxified LukED antigens conferred protection against staphylococcal skin infection in mice. Consequently, knowledge of in vivo-expressed virulence determinants can be successfully deployed to identify and select promising candidates for optimized design of effective vaccine antigens against S. aureus. Notably, this approach should be broadly applicable to numerous other pathogens. IMPORTANCE Vaccination is an attractive strategy for preventing bacterial infections in an age of increased antimicrobial resistance. However, vaccine development frequently suffers significant setbacks when candidate antigens that show promising results in in vitro experimentation fail to protect from disease. An alluring strategy is to focus resources on developing bacterial virulence factors that are expressed during disease establishment or maintenance and are critical for bacterial in-host survival as vaccine targets. While expression profiles of many virulence factors have been characterized in detail in vitro, our knowledge of their in vivo expression profiles is still scarce. Here, using a high-throughput qRT-PCR approach, we identified two highly expressed leukotoxins in a murine infection model and showed that genetically detoxified derivatives of these elicited a protective immune response in a murine skin infection model. Therefore, in vivo gene expression can inform the selection of promising candidates for the design of effective vaccine antigens.
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Affiliation(s)
- Andreas F. Haag
- GSK, Siena, Italy
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom
| | | | | | | | - Tarcisio Brignoli
- GSK, Siena, Italy
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
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Staphylococcus ratti sp. nov. Isolated from a Lab Rat. Pathogens 2022; 11:pathogens11010051. [PMID: 35055999 PMCID: PMC8779110 DOI: 10.3390/pathogens11010051] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/27/2021] [Accepted: 12/30/2021] [Indexed: 01/27/2023] Open
Abstract
Staphylococci from the Staphylococcus intermedius-Staphylococcus hyicus species group include numerous animal pathogens and are an important reservoir of virulence and antimicrobial resistance determinants. Due to their pathogenic potential, they are possible causative agents of zoonoses in humans; therefore, it is important to address the properties of these strains. Here we used a polyphasic taxonomic approach to characterize the coagulase-negative staphylococcal strain NRL/St 03/464T, isolated from the nostrils of a healthy laboratory rat during a microbiological screening of laboratory animals. The 16S rRNA sequence, MALDI-TOF mass spectrometry and positive urea hydrolysis and beta-glucuronidase tests clearly distinguished it from closely related Staphylococcus spp. All analyses have consistently shown that the closest relative is Staphylococcus chromogenes; however, values of digital DNA-DNA hybridization <35.3% and an average nucleotide identity <81.4% confirmed that the analyzed strain is a distinct Staphylococcus species. Whole-genome sequencing and expert annotation of the genome revealed the presence of novel variable genetic elements, including two plasmids named pSR9025A and pSR9025B, prophages, genomic islands and a composite transposon that may confer selective advantages to other bacteria and enhance their survival. Based on phenotypic, phylogenetic and genomic data obtained in this study, the strain NRL/St 03/464T (= CCM 9025T = LMG 31873T = DSM 111348T) represents a novel species with the suggested name Staphylococcus ratti sp. nov.
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Barber CC, Zhang W. Small molecule natural products in human nasal/oral microbiota. J Ind Microbiol Biotechnol 2021; 48:6129854. [PMID: 33945611 PMCID: PMC8210680 DOI: 10.1093/jimb/kuab010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/07/2020] [Indexed: 12/26/2022]
Abstract
Small molecule natural products are a chemically diverse class of biomolecules that fulfill myriad biological functions, including autoregulation, communication with microbial neighbors and the host, interference competition, nutrient acquisition, and resistance to oxidative stress. Human commensal bacteria are increasingly recognized as a potential source of new natural products, which may provide insight into the molecular ecology of many different human body sites as well as novel scaffolds for therapeutic development. Here, we review the scientific literature on natural products derived from residents of the human nasal/oral cavity, discuss their discovery, biosynthesis, and ecological roles, and identify key questions in the study of these compounds.
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Affiliation(s)
- Colin Charles Barber
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley 94720, USA
| | - Wenjun Zhang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley 94720, USA.,Chan-Zuckerberg Biohub, San Francisco 94158, USA
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Lerche CJ, Schwartz F, Theut M, Fosbøl EL, Iversen K, Bundgaard H, Høiby N, Moser C. Anti-biofilm Approach in Infective Endocarditis Exposes New Treatment Strategies for Improved Outcome. Front Cell Dev Biol 2021; 9:643335. [PMID: 34222225 PMCID: PMC8249808 DOI: 10.3389/fcell.2021.643335] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/04/2021] [Indexed: 12/13/2022] Open
Abstract
Infective endocarditis (IE) is a life-threatening infective disease with increasing incidence worldwide. From early on, in the antibiotic era, it was recognized that high-dose and long-term antibiotic therapy was correlated to improved outcome. In addition, for several of the common microbial IE etiologies, the use of combination antibiotic therapy further improves outcome. IE vegetations on affected heart valves from patients and experimental animal models resemble biofilm infections. Besides the recalcitrant nature of IE, the microorganisms often present in an aggregated form, and gradients of bacterial activity in the vegetations can be observed. Even after appropriate antibiotic therapy, such microbial formations can often be identified in surgically removed, infected heart valves. Therefore, persistent or recurrent cases of IE, after apparent initial infection control, can be related to biofilm formation in the heart valve vegetations. On this background, the present review will describe potentially novel non-antibiotic, antimicrobial approaches in IE, with special focus on anti-thrombotic strategies and hyperbaric oxygen therapy targeting the biofilm formation of the infected heart valves caused by Staphylococcus aureus. The format is translational from preclinical models to actual clinical treatment strategies.
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Affiliation(s)
- Christian Johann Lerche
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Franziska Schwartz
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Marie Theut
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Emil Loldrup Fosbøl
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Kasper Iversen
- Department of Cardiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.,Department of Emergency Medicine, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark
| | - Henning Bundgaard
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.,Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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Pang S, Daley DA, Sahibzada S, Mowlaboccus S, Stegger M, Coombs GW. Genome-wide association studies reveal candidate genes associated to bacteraemia caused by ST93-IV CA-MRSA. BMC Genomics 2021; 22:418. [PMID: 34090342 PMCID: PMC8180019 DOI: 10.1186/s12864-021-07738-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 05/25/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The global emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has seen the dominance of specific clones in different regions around the world with the PVL-positive ST93-IV as the predominant CA-MRSA clone in Australia. In this study we applied a genome-wide association study (GWAS) approach on a collection of Australian ST93-IV MRSA genomes to screen for genetic traits that might have assisted the ongoing transmission of ST93-IV in Australia. We also compared the genomes of ST93-IV bacteraemia and non-bacteraemia isolates to search for potential virulence genes associated with bacteraemia. RESULTS Based on single nucleotide polymorphism phylogenetics we revealed two distinct ST93-IV clades circulating concurrently in Australia. One of the clades contained isolates primarily isolated in the northern regions of Australia whilst isolates in the second clade were distributed across the country. Analyses of the ST93-IV genome plasticity over a 15-year period (2002-2017) revealed an observed gain in accessory genes amongst the clone's population. GWAS analysis on the bacteraemia isolates identified two gene candidates that have previously been associated to this kind of infection. CONCLUSIONS Although this hypothesis was not tested here, it is possible that the emergence of a ST93-IV clade containing additional virulence genes might be related to the high prevalence of ST93-IV infections amongst the indigenous population living in the northern regions of Australia. More importantly, our data also demonstrated that GWAS can reveal candidate genes for further investigations on the pathogenesis and evolution of MRSA strains within a same lineage.
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Affiliation(s)
- Stanley Pang
- Antimicrobial Resistance and Infectious Diseases (AMRID) Research Laboratory, Murdoch University, Murdoch, Western Australia, Australia.
- Department of Microbiology, PathWest Laboratory Medicine-WA, Fiona Stanley Hospital, Murdoch, Western Australia, Australia.
| | - Denise A Daley
- Australian Group on Antimicrobial Resistance (AGAR), Fiona Stanley Hospital, Murdoch, Australia
| | - Shafi Sahibzada
- Antimicrobial Resistance and Infectious Diseases (AMRID) Research Laboratory, Murdoch University, Murdoch, Western Australia, Australia
| | - Shakeel Mowlaboccus
- Antimicrobial Resistance and Infectious Diseases (AMRID) Research Laboratory, Murdoch University, Murdoch, Western Australia, Australia
| | - Marc Stegger
- Antimicrobial Resistance and Infectious Diseases (AMRID) Research Laboratory, Murdoch University, Murdoch, Western Australia, Australia
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Geoffrey W Coombs
- Antimicrobial Resistance and Infectious Diseases (AMRID) Research Laboratory, Murdoch University, Murdoch, Western Australia, Australia
- Department of Microbiology, PathWest Laboratory Medicine-WA, Fiona Stanley Hospital, Murdoch, Western Australia, Australia
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Takemiya K, Røise JJ, He M, Taing C, Rodriguez AG, Murthy N, Goodman MM, Taylor WR. Maltohexaose-indocyanine green (MH-ICG) for near infrared imaging of endocarditis. PLoS One 2021; 16:e0247673. [PMID: 33647027 PMCID: PMC7920357 DOI: 10.1371/journal.pone.0247673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 02/11/2021] [Indexed: 11/19/2022] Open
Abstract
Infectious endocarditis is a life-threatening disease, and diagnostics are urgently needed to accurately diagnose this disease especially in the case of prosthetic valve endocarditis. We show here that maltohexaose conjugated to indocyanine green (MH-ICG) can detect Staphylococcus aureus (S. aureus) infection in a rat model of infective endocarditis. The affinity of MH-ICG to S. aureus was determined and had a Km and Vmax of 5.4 μM and 3.0 X 10−6 μmol/minutes/108 CFU, respectively. MH-ICG had no detectable toxicity to mammalian cells at concentrations as high as 100 μM. The in vivo efficiency of MH-ICG in rats was evaluated using a right heart endocarditis model, and the accumulation of MH-ICG in the bacterial vegetations was 2.5 ± 0.2 times higher than that in the control left ventricular wall. The biological half-life of MH-ICG in healthy rats was 14.0 ± 1.3 minutes, and approximately 50% of injected MH-ICG was excreted into the feces after 24 hours. These data demonstrate that MH-ICG was internalized by bacteria with high specificity and that MH-ICG specifically accumulated in bacterial vegetations in a rat model of endocarditis. These results demonstrate the potential efficacy of this agent in the detection of infective endocarditis.
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Affiliation(s)
- Kiyoko Takemiya
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United states of America
- * E-mail: (KT); (NM); (MMG); (WRT)
| | - Joachim J. Røise
- Department of Bioengineering, University of California at Berkeley, Berkeley, California, United States of America
- Department of Chemistry, University of California at Berkeley, Berkeley, California, United States of America
| | - Maomao He
- Department of Bioengineering, University of California at Berkeley, Berkeley, California, United States of America
| | - Chung Taing
- Department of Chemistry, University of California at Berkeley, Berkeley, California, United States of America
| | - Alexander G. Rodriguez
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United states of America
| | - Niren Murthy
- Department of Bioengineering, University of California at Berkeley, Berkeley, California, United States of America
- * E-mail: (KT); (NM); (MMG); (WRT)
| | - Mark M. Goodman
- Department of Radiology and Imaging Sciences, Emory Center for Systems Imaging, Emory University School of Medicine, Atlanta, Georgia, United states of America
- * E-mail: (KT); (NM); (MMG); (WRT)
| | - W. Robert Taylor
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United states of America
- Cardiology Division, Atlanta Veterans Affairs Medical Center, Atlanta, Georgia, United states of America
- Department of Biomedical Engineering, Emory University School of Medicine and Georgia Institute of Technology, Atlanta, Georgia, United states of America
- * E-mail: (KT); (NM); (MMG); (WRT)
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Molecular Epidemiology of Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus in Wild, Captive and Laboratory Rats: Effect of Habitat on the Nasal S. aureus Population. Toxins (Basel) 2020; 12:toxins12020080. [PMID: 31991690 PMCID: PMC7076793 DOI: 10.3390/toxins12020080] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/10/2020] [Accepted: 01/20/2020] [Indexed: 11/16/2022] Open
Abstract
Rats are a reservoir of human- and livestock-associated methicillin-resistant Staphylococcus aureus (MRSA). However, the composition of the natural S. aureus population in wild and laboratory rats is largely unknown. Here, 144 nasal S. aureus isolates from free-living wild rats, captive wild rats and laboratory rats were genotyped and profiled for antibiotic resistances and human-specific virulence genes. The nasal S. aureus carriage rate was higher among wild rats (23.4%) than laboratory rats (12.3%). Free-living wild rats were primarily colonized with isolates of clonal complex (CC) 49 and CC130 and maintained these strains even in husbandry. Moreover, upon livestock contact, CC398 isolates were acquired. In contrast, laboratory rats were colonized with many different S. aureus lineages—many of which are commonly found in humans. Five captive wild rats were colonized with CC398-MRSA. Moreover, a single CC30-MRSA and two CC130-MRSA were detected in free-living or captive wild rats. Rat-derived S. aureus isolates rarely harbored the phage-carried immune evasion gene cluster or superantigen genes, suggesting long-term adaptation to their host. Taken together, our study revealed a natural S. aureus population in wild rats, as well as a colonization pressure on wild and laboratory rats by exposure to livestock- and human-associated S. aureus, respectively.
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Qosimah D, Aryani DE, Beltran MAG, Aulanni'am A. Diabetes sepsis on Wistar rat strain ( Rattus norvegicus) induced by streptozotocin and bacteria Staphylococcus aureus. Vet World 2019; 12:849-854. [PMID: 31440004 PMCID: PMC6661491 DOI: 10.14202/vetworld.2019.849-854] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/18/2019] [Indexed: 01/21/2023] Open
Abstract
Background and Aim: Sepsis is characterized by loss of control of the inflammatory response, which can be triggered by various microorganisms and toxic secretions. The mortality rate increases due to impaired endothelial function caused dysfunctional organ systems. Diabetes is closely related to sepsis. The study aimed to determine the method of using animal models of sepsis diabetes through a combination of streptozotocin (STZ) and Staphylococcus aureus infection based on biological marker parameters. Materials and Methods: A total of 30 male Wistar rats of 2.5-3 months old weighing approximately 150-250 g body weight (BW) divided into six treatment groups with five replications per group were used in the study. Treatment A was negative control (healthy rats) and Treatment B was the positive control (with diabetes) where rats were given STZ dose at 45 mg/kg BW on day 8 intraperitoneally (IP). The blood glucose was measured on day 10, Treatment C was a positive control (bacteria), rats inoculated with S. aureus with a concentration of 108 CFU/mL on day 8 given IP and observed sepsis conditions on day 10th. Treatment group (D, E, and F): Rats given STZ dose at 45 mg/kg BW on day 8th by IP and measured blood glucose on day 10th, then inoculated with S. aureus with different concentrations of 105 CFU/mL, 106 CFU/mL, and 107 CFU/mL on the 10th day, respectively, and were later observed the condition of sepsis on day 12th. Data on diabetes bacteremia were quantitative used blood glucose levels, the bacterial count, and C-reactive protein (CRP) and were analyzed using the one-way analysis of variance test with a confidence level of 95%. Physical examination (temperature and respiration) is qualitative. Results: Physical examination showed that all treatments had a normal temperature, an increased pulse in Groups D, E, and F and a decrease in respiratory rate in the treatment of E and F, the bacteria found in the vital organs in all groups, and CRP levels were not significantly different at all. Conclusion: Animal model of diabetes sepsis can be observed through a combination of pancreas damage, and respiration, the bacteria in the vital organs.
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Affiliation(s)
- Dahliatul Qosimah
- Laboratory of Microbiology and Immunology, Faculty of Veterinary Medicine, Brawijaya University, Indonesia
| | - Dhita Evi Aryani
- Laboratory of Pharmacology, Faculty of Veterinary Medicine, Brawijaya University, Indonesia
| | - Ma Asuncion Guiang Beltran
- Department of Microbiology and Public Health, College of Veterinary Medicine, Tarlac Agricultural University, Camiling, Tarlac, Philippines
| | - Aulanni'am Aulanni'am
- Laboratory of Biochemical, Faculty of Veterinary Medicine, Brawijaya University, Indonesia
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10
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Chen C, Hooper DC. Effect of Staphylococcus aureus Tet38 native efflux pump on in vivo response to tetracycline in a murine subcutaneous abscess model. J Antimicrob Chemother 2019; 73:720-723. [PMID: 29216347 DOI: 10.1093/jac/dkx432] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 10/24/2017] [Indexed: 11/13/2022] Open
Abstract
Objectives Staphylococcus aureus native efflux pump Tet38 confers resistance to tetracycline when overexpressed. tet38 expression is selectively upregulated in infection sites. This study evaluated the effect of Tet38 on tetracycline response in a murine subcutaneous abscess model. Methods S. aureus MW2 and its tet38 mutant were injected subcutaneously on the opposite flanks of each mouse. The infected mice were treated with tetracycline (10 mg/kg) or PBS (control) intraperitoneally every 12 h. The efficacy of tetracycline against S. aureus was measured by the relative change in viable bacteria in the abscesses 24 h after infection compared with the initial inoculum. Plasmid-based tet38-complemented strains were created and used to infect the mice followed by tetracycline or PBS treatment. Results The increased bacterial loads of S. aureus MW2 and its tet38 mutant in the abscess after 24 h were similar. Tetracycline produced significant decreases of both MW2 and the tet38 mutant compared with control. Although the tetracycline MICs for MW2 and the tet38 mutant did not differ in vitro, the antibacterial effect of tetracycline was significantly 2-fold greater in the tet38 mutant compared with the MW2 parental strain in vivo with a decrease of 0.67 ± 0.21 and 0.35 ± 0.19 log10 cfu/abscess, respectively (P < 0.05). The increased tetracycline activity in the tet38 mutant was complemented by plasmid-encoded tet38. Conclusions This study demonstrated that selective increased expression of tet38 in an abscess can affect tetracycline efficacy against S. aureus in vivo, highlighting an effect of native efflux pumps on response to therapy not reflected by testing in vitro.
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Affiliation(s)
- Chunhui Chen
- Division of Infectious Diseases, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - David C Hooper
- Division of Infectious Diseases, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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11
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Dual Gene Expression Analysis Identifies Factors Associated with Staphylococcus aureus Virulence in Diabetic Mice. Infect Immun 2019; 87:IAI.00163-19. [PMID: 30833333 DOI: 10.1128/iai.00163-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen of the skin. The global burden of diabetes is high, with S. aureus being a major complication of diabetic wound infections. We investigated how the diabetic environment influences S. aureus skin infection and observed an increased susceptibility to infection in mouse models of both type I and type II diabetes. A dual gene expression approach was taken to investigate transcriptional alterations in both the host and bacterium after infection. While analysis of the host response revealed only minor changes between infected control and diabetic mice, we observed that S. aureus isolated from diabetic mice had significant increases in the levels of genes associated with translation and posttranslational modification and chaperones and reductions in the levels of genes associated with amino acid transport and metabolism. One family of genes upregulated in S. aureus isolated from diabetic lesions encoded the Clp proteases, associated with the misfolded protein response. The Clp proteases were found to be partially glucose regulated as well as influencing the hemolytic activity of S. aureus Strains lacking the Clp proteases ClpX, ClpC, and ClpP were significantly attenuated in our animal model of skin infection, with significant reductions observed in dermonecrosis and bacterial burden. In particular, mutations in clpP and clpX were significantly attenuated and remained attenuated in both normal and diabetic mice. Our data suggest that the diabetic environment also causes changes to occur in invading pathogens, and one of these virulence determinants is the Clp protease system.
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12
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McFarlane JS, Davis CL, Lamb AL. Staphylopine, pseudopaline, and yersinopine dehydrogenases: A structural and kinetic analysis of a new functional class of opine dehydrogenase. J Biol Chem 2018; 293:8009-8019. [PMID: 29618515 PMCID: PMC5971449 DOI: 10.1074/jbc.ra118.002007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/03/2018] [Indexed: 11/06/2022] Open
Abstract
Opine dehydrogenases (ODHs) from the bacterial pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and Yersinia pestis perform the final enzymatic step in the biosynthesis of a new class of opine metallophores, which includes staphylopine, pseudopaline, and yersinopine, respectively. Growing evidence indicates an important role for this pathway in metal acquisition and virulence, including in lung and burn-wound infections (P. aeruginosa) and in blood and heart infections (S. aureus). Here, we present kinetic and structural characterizations of these three opine dehydrogenases. A steady-state kinetic analysis revealed that the three enzymes differ in α-keto acid and NAD(P)H substrate specificity and nicotianamine-like substrate stereoselectivity. The structural basis for these differences was determined from five ODH X-ray crystal structures, ranging in resolution from 1.9 to 2.5 Å, with or without NADP+ bound. Variation in hydrogen bonding with NADPH suggested an explanation for the differential recognition of this substrate by these three enzymes. Our analysis further revealed candidate residues in the active sites required for binding of the α-keto acid and nicotianamine-like substrates and for catalysis. This work reports the first structural kinetic analyses of enzymes involved in opine metallophore biosynthesis in three important bacterial pathogens of humans.
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Affiliation(s)
- Jeffrey S McFarlane
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Cara L Davis
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045
| | - Audrey L Lamb
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045; Department of Chemistry, University of Kansas, Lawrence, Kansas 66045.
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13
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Diabetes mellitus und Immunantwort bei pyogenen Infektionen. DIABETOLOGE 2018. [DOI: 10.1007/s11428-018-0320-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Verstraete MM, Perez-Borrajero C, Brown KL, Heinrichs DE, Murphy MEP. SbnI is a free serine kinase that generates O -phospho-l-serine for staphyloferrin B biosynthesis in Staphylococcus aureus. J Biol Chem 2018; 293:6147-6160. [PMID: 29483190 DOI: 10.1074/jbc.ra118.001875] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/15/2018] [Indexed: 12/22/2022] Open
Abstract
Staphyloferrin B (SB) is an iron-chelating siderophore produced by Staphylococcus aureus in invasive infections. Proteins for SB biosynthesis and export are encoded by the sbnABCDEFGHI gene cluster, in which SbnI, a member of the ParB/Srx superfamily, acts as a heme-dependent transcriptional regulator of the sbn locus. However, no structural or functional information about SbnI is available. Here, a crystal structure of SbnI revealed striking structural similarity to an ADP-dependent free serine kinase, SerK, from the archaea Thermococcus kodakarensis We found that features of the active sites are conserved, and biochemical assays and 31P NMR and HPLC analyses indicated that SbnI is also a free serine kinase but uses ATP rather than ADP as phosphate donor to generate the SB precursor O-phospho-l-serine (OPS). SbnI consists of two domains, and elevated B-factors in domain II were consistent with the open-close reaction mechanism previously reported for SerK. Mutagenesis of Glu20 and Asp58 in SbnI disclosed that they are required for kinase activity. The only known OPS source in bacteria is through the phosphoserine aminotransferase activity of SerC within the serine biosynthesis pathway, and we demonstrate that an S. aureus serC mutant is a serine auxotroph, consistent with a function in l-serine biosynthesis. However, the serC mutant strain could produce SB when provided l-serine, suggesting that SbnI produces OPS for SB biosynthesis in vivo These findings indicate that besides transcriptionally regulating the sbn locus, SbnI also has an enzymatic role in the SB biosynthetic pathway.
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Affiliation(s)
| | - Cecilia Perez-Borrajero
- the Genome Sciences and Technology Program Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | | | - David E Heinrichs
- the Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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15
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Gowrishankar G, Hardy J, Wardak M, Namavari M, Reeves RE, Neofytou E, Srinivasan A, Wu JC, Contag CH, Gambhir SS. Specific Imaging of Bacterial Infection Using 6″- 18F-Fluoromaltotriose: A Second-Generation PET Tracer Targeting the Maltodextrin Transporter in Bacteria. J Nucl Med 2017; 58:1679-1684. [PMID: 28490473 DOI: 10.2967/jnumed.117.191452] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/25/2017] [Indexed: 02/03/2023] Open
Abstract
6″-18F-fluoromaltotriose is a PET tracer that can potentially be used to image and localize most bacterial infections, much like 18F-FDG has been used to image and localize most cancers. However, unlike 18F-FDG, 6″-18F-fluoromaltotriose is not taken up by inflammatory lesions and appears to be specific to bacterial infections by targeting the maltodextrin transporter that is expressed in gram-positive and gram-negative strains of bacteria. Methods: 6″-18F-fluoromaltotriose was synthesized with high radiochemical purity and evaluated in several clinically relevant bacterial strains in cultures and in living mice. Results: 6″-18F-fluoromaltotriose was taken up in both gram-positive and gram-negative bacterial strains. 6″-18F-fluoromaltotriose was also able to detect Pseudomonas aeruginosa in a clinically relevant mouse model of wound infection. The utility of 6″-18F-fluoromaltotriose to help monitor antibiotic therapies was also evaluated in rats. Conclusion: 6″-18F-fluoromaltotriose is a promising new tracer that has significant diagnostic utility, with the potential to change the clinical management of patients with infectious diseases of bacterial origin.
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Affiliation(s)
- Gayatri Gowrishankar
- Department of Radiology, Stanford University School of Medicine, Stanford, California
| | - Jonathan Hardy
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California
| | - Mirwais Wardak
- Department of Radiology, Stanford University School of Medicine, Stanford, California
| | - Mohammad Namavari
- Department of Radiology, Stanford University School of Medicine, Stanford, California
| | | | - Evgenios Neofytou
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California; and
| | - Ananth Srinivasan
- Department of Radiology, Stanford University School of Medicine, Stanford, California
| | - Joseph C Wu
- Department of Radiology, Stanford University School of Medicine, Stanford, California.,Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California; and
| | - Christopher H Contag
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California
| | - Sanjiv Sam Gambhir
- Department of Radiology, Stanford University School of Medicine, Stanford, California .,Department of Bioengineering, Stanford University School of Medicine, Stanford, California
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16
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Innate Immunity of Adipose Tissue in Rodent Models of Local and Systemic Staphylococcus aureus Infection. Mediators Inflamm 2017; 2017:5315602. [PMID: 28428684 PMCID: PMC5385907 DOI: 10.1155/2017/5315602] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 02/13/2017] [Indexed: 12/31/2022] Open
Abstract
Background. The role of adipose tissue in systemic inflammation during bacterial infection is unclear. Effects of Staphylococcus aureus infection on adipocytes in rodent models of experimental endocarditis and peritonitis, the impact of S. aureus infection on gene expression in epididymal and subcutaneous adipose tissue, and effects of S. aureus infection on the toll-like receptor-2- (TLR2-) cathelicidin pathway in vivo and in vitro were investigated. Material and methods. The rat model of catheter-induced S. aureus endocarditis and the mouse model of S. aureus-induced peritonitis were used for infection experiments, gene expression profiling in adipose tissue, and measurement of cytokines. 3T3-L1 adipocytes were analyzed for expression of the TLR2-cathelicidin pathway. Results. Upon systemic bacterial infection by S. aureus, there is a shift from anti- to proinflammatory cytokines in serum and in adipose tissue gene expression. The TLR2-cathelicidin pathway is increasingly expressed during adipocyte differentiation in vitro and is induced upon stimulation by synthetic lipopeptides. Conclusions. Systemic infection by Gram-positive bacteria induces proinflammatory transformation of adipose tissue sites distinct from infection sites, documented on the levels of gene expression and secreted mediators. The TLR2-cathelicidine pathway is expressed and highly inducible in adipocytes in vitro. Lipopeptides are important immune-modulators of adipocytes in both gene expression and protein secretion.
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17
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Fields FR, Lee SW, McConnell MJ. Using bacterial genomes and essential genes for the development of new antibiotics. Biochem Pharmacol 2016; 134:74-86. [PMID: 27940263 DOI: 10.1016/j.bcp.2016.12.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 12/05/2016] [Indexed: 10/20/2022]
Abstract
The shrinking antibiotic development pipeline together with the global increase in antibiotic resistant infections requires that new molecules with antimicrobial activity are developed. Traditional empirical screening approaches of natural and non-natural compounds have identified the majority of antibiotics that are currently available, however this approach has produced relatively few new antibiotics over the last few decades. The vast amount of bacterial genome sequence information that has become available since the sequencing of the first bacterial genome more than 20years ago holds potential for contributing to the discovery of novel antimicrobial compounds. Comparative genomic approaches can identify genes that are highly conserved within and between bacterial species, and thus may represent genes that participate in key bacterial processes. Whole genome mutagenesis studies can also identify genes necessary for bacterial growth and survival under different environmental conditions, making them attractive targets for the development of novel inhibitory compounds. In addition, transcriptomic and proteomic approaches can be used to characterize RNA and protein levels on a cellular scale, providing information on bacterial physiology that can be applied to antibiotic target identification. Finally, bacterial genomes can be mined to identify biosynthetic pathways that produce many intrinsic antimicrobial compounds and peptides. In this review, we provide an overview of past and current efforts aimed at using bacterial genomic data in the discovery and development of novel antibiotics.
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Affiliation(s)
- Francisco R Fields
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States
| | - Shaun W Lee
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States
| | - Michael J McConnell
- Biomedical Institute of Seville, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.
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18
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Omics Approaches for the Study of Adaptive Immunity to Staphylococcus aureus and the Selection of Vaccine Candidates. Proteomes 2016; 4:proteomes4010011. [PMID: 28248221 PMCID: PMC5217363 DOI: 10.3390/proteomes4010011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 02/05/2016] [Accepted: 03/01/2016] [Indexed: 01/20/2023] Open
Abstract
Staphylococcus aureus is a dangerous pathogen both in hospitals and in the community. Due to the crisis of antibiotic resistance, there is an urgent need for new strategies to combat S. aureus infections, such as vaccination. Increasing our knowledge about the mechanisms of protection will be key for the successful prevention or treatment of S. aureus invasion. Omics technologies generate a comprehensive picture of the physiological and pathophysiological processes within cells, tissues, organs, organisms and even populations. This review provides an overview of the contribution of genomics, transcriptomics, proteomics, metabolomics and immunoproteomics to the current understanding of S. aureus‑host interaction, with a focus on the adaptive immune response to the microorganism. While antibody responses during colonization and infection have been analyzed in detail using immunoproteomics, the full potential of omics technologies has not been tapped yet in terms of T-cells. Omics technologies promise to speed up vaccine development by enabling reverse vaccinology approaches. In consequence, omics technologies are powerful tools for deepening our understanding of the “superbug” S. aureus and for improving its control.
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Kobylarz MJ, Grigg JC, Liu Y, Lee MSF, Heinrichs DE, Murphy MEP. Deciphering the Substrate Specificity of SbnA, the Enzyme Catalyzing the First Step in Staphyloferrin B Biosynthesis. Biochemistry 2016; 55:927-39. [PMID: 26794841 PMCID: PMC5084695 DOI: 10.1021/acs.biochem.5b01045] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Staphylococcus aureus assembles the siderophore,
staphyloferrin B, from l-2,3-diaminopropionic acid (l-Dap), α-ketoglutarate, and citrate. Recently, SbnA and SbnB
were shown to produce l-Dap and α-ketoglutarate from O-phospho-l-serine (OPS) and l-glutamate.
SbnA is a pyridoxal 5′-phosphate (PLP)-dependent enzyme with
homology to O-acetyl-l-serine sulfhydrylases;
however, SbnA utilizes OPS instead of O-acetyl-l-serine (OAS), and l-glutamate serves as a nitrogen
donor instead of a sulfide. In this work, we examined how SbnA dictates
substrate specificity for OPS and l-glutamate using a combination
of X-ray crystallography, enzyme kinetics, and site-directed mutagenesis.
Analysis of SbnA crystals incubated with OPS revealed the structure
of the PLP-α-aminoacrylate intermediate. Formation of the intermediate
induced closure of the active site pocket by narrowing the channel
leading to the active site and forming a second substrate binding
pocket that likely binds l-glutamate. Three active site residues
were identified: Arg132, Tyr152, Ser185 that were essential for OPS
recognition and turnover. The Y152F/S185G SbnA double mutant was completely
inactive, and its crystal structure revealed that the mutations induced
a closed form of the enzyme in the absence of the α-aminoacrylate
intermediate. Lastly, l-cysteine was shown to be a competitive
inhibitor of SbnA by forming a nonproductive external aldimine with
the PLP cofactor. These results suggest a regulatory link between
siderophore and l-cysteine biosynthesis, revealing a potential
mechanism to reduce iron uptake under oxidative stress.
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Affiliation(s)
- Marek J Kobylarz
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z3
| | - Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z3
| | - Yunan Liu
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z3
| | - Mathew S F Lee
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z3
| | | | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z3
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20
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Jang S. Multidrug efflux pumps in Staphylococcus aureus and their clinical implications. J Microbiol 2016; 54:1-8. [DOI: 10.1007/s12275-016-5159-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 10/29/2015] [Accepted: 10/30/2015] [Indexed: 12/13/2022]
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21
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Dastgheyb SS, Otto M. Staphylococcal adaptation to diverse physiologic niches: an overview of transcriptomic and phenotypic changes in different biological environments. Future Microbiol 2015; 10:1981-95. [PMID: 26584249 DOI: 10.2217/fmb.15.116] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Host niches can differ strongly regarding, for example, oxygen tension, pH or nutrient availability. Staphylococcus aureus and other staphylococci are common colonizers of human epithelia as well as important human pathogens. The phenotypes that they show in different host environments, and the corresponding bacterial transcriptomes and proteomes, are currently under intense investigation. In this review, we examine the available literature describing staphylococcal phenotypes, such as expression of virulence factors, gross morphologic characteristics and growth patterns, in various physiological environments. Going forward, these studies will help researchers and clinicians to form an enhanced and more detailed picture of the interactions existing between the host and staphylococci as some of its most frequent colonizers and invaders.
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Affiliation(s)
- Sana S Dastgheyb
- Pathogen Molecular Genetics Section, Laborartory of Bacteriology, National Institute of Allergy & Infectious Diseases, The National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laborartory of Bacteriology, National Institute of Allergy & Infectious Diseases, The National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
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Laakso HA, Marolda CL, Pinter TB, Stillman MJ, Heinrichs DE. A Heme-responsive Regulator Controls Synthesis of Staphyloferrin B in Staphylococcus aureus. J Biol Chem 2015; 291:29-40. [PMID: 26534960 DOI: 10.1074/jbc.m115.696625] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Indexed: 11/06/2022] Open
Abstract
Staphylococcus aureus possesses a multitude of mechanisms by which it can obtain iron during growth under iron starvation conditions. It expresses an effective heme acquisition system (the iron-regulated surface determinant system), it produces two carboxylate-type siderophores staphyloferrin A and staphyloferrin B (SB), and it expresses transporters for many other siderophores that it does not synthesize. The ferric uptake regulator protein regulates expression of genes encoding all of these systems. Mechanisms of fine-tuning expression of iron-regulated genes, beyond simple iron regulation via ferric uptake regulator, have not been uncovered in this organism. Here, we identify the ninth gene of the sbn operon, sbnI, as encoding a ParB/Spo0J-like protein that is required for expression of genes in the sbn operon from sbnD onward. Expression of sbnD-I is drastically decreased in an sbnI mutant, and the mutant does not synthesize detectable SB during early phases of growth. Thus, SB-mediated iron acquisition is impaired in an sbnI mutant strain. We show that the protein forms dimers and tetramers in solution and binds to DNA within the sbnC coding region. Moreover, we show that SbnI binds heme and that heme-bound SbnI does not bind DNA. Finally, we show that providing exogenous heme to S. aureus growing in an iron-free medium results in delayed synthesis of SB. This is the first study in S. aureus that identifies a DNA-binding regulatory protein that senses heme to control gene expression for siderophore synthesis.
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Affiliation(s)
| | | | | | | | - David E Heinrichs
- From the Departments of Microbiology and Immunology and Centre for Human Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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