1
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Lopez JG, Hein Y, Erez A. Grow now, pay later: When should a bacterium go into debt? Proc Natl Acad Sci U S A 2024; 121:e2314900121. [PMID: 38588417 PMCID: PMC11032434 DOI: 10.1073/pnas.2314900121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 03/03/2024] [Indexed: 04/10/2024] Open
Abstract
Microbes grow in a wide variety of environments and must balance growth and stress resistance. Despite the prevalence of such trade-offs, understanding of their role in nonsteady environments is limited. In this study, we introduce a mathematical model of "growth debt," where microbes grow rapidly initially, paying later with slower growth or heightened mortality. We first compare our model to a classical chemostat experiment, validating our proposed dynamics and quantifying Escherichia coli's stress resistance dynamics. Extending the chemostat theory to include serial-dilution cultures, we derive phase diagrams for the persistence of "debtor" microbes. We find that debtors cannot coexist with nondebtors if "payment" is increased mortality but can coexist if it lowers enzyme affinity. Surprisingly, weak noise considerably extends the persistence of resistance elements, pertinent for antibiotic resistance management. Our microbial debt theory, broadly applicable across many environments, bridges the gap between chemostat and serial dilution systems.
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Affiliation(s)
- Jaime G. Lopez
- Department of Bioengineering, Stanford University, Stanford, CA94305
- Racah Institute of Physics, The Hebrew University, Jerusalem9190401, Israel
- Department of Applied Physics, Stanford University, Stanford, CA94305
| | - Yaïr Hein
- Institute for Theoretical Physics, Utrecht University, Utrecht3584 CC, Netherlands
| | - Amir Erez
- Racah Institute of Physics, The Hebrew University, Jerusalem9190401, Israel
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2
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Valencia EY, de Moraes Gomes F, Ospino K, Spira B. RpoS role in antibiotic resistance, tolerance and persistence in E. coli natural isolates. BMC Microbiol 2024; 24:72. [PMID: 38443813 DOI: 10.1186/s12866-024-03222-7] [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: 11/29/2023] [Accepted: 02/12/2024] [Indexed: 03/07/2024] Open
Abstract
BACKGROUND The intrinsic concentration of RpoS, the second most abundant sigma factor, varies widely across the E. coli species. Bacterial isolates that express high levels of RpoS display high resistance to environmental stresses, such as temperature, pH and osmolarity shifts, but are less nutritional competent, making them less capable of utilising alternative nutrient sources. The role of RpoS in antibiotic resistance and persistence in standard laboratory domesticated strains has been examined in several studies, most demonstrating a positive role for RpoS. RESULTS Using disk diffusion assays we examined bacterial resistance to 15 different antibiotics, including β -lactams (penicillins, monobactams, carbapenems and cephalosporins), aminoglycosides, quinolones and anti-folates, in a representative collection of 328 E. coli natural isolates displaying a continuum of different levels of RpoS. There was an overall trend that isolates with higher levels of RpoS were slightly more resistant to these antibiotics. In addition, the effect of RpoS on bacterial tolerance and persistence to 3 different antibiotics - ampicillin, ciprofloxacin and kanamycin was evaluated through time-kill curves. Again, there was a small beneficial effect of RpoS on tolerance and persistence to these antibiotics, but this difference was not statistically significant. Finally, a K-12 strain expressing high levels of RpoS was compared with its isogenic RpoS-null counterpart, and no significant effect of RpoS was found. CONCLUSION Based on a representative collection of the species E. coli, RpoS was found to have a very small impact on antibiotic resistance, tolerance, or persistence.
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Affiliation(s)
- Estela Ynés Valencia
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Felipe de Moraes Gomes
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Katia Ospino
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Beny Spira
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
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3
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Adi Wicaksono W, Braun M, Bernhardt J, Riedel K, Cernava T, Berg G. Trade-off for survival: Microbiome response to chemical exposure combines activation of intrinsic resistances and adapted metabolic activity. ENVIRONMENT INTERNATIONAL 2022; 168:107474. [PMID: 35988321 DOI: 10.1016/j.envint.2022.107474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
The environmental microbiota is increasingly exposed to chemical pollution. While the emergence of multi-resistant pathogens is recognized as a global challenge, our understanding of antimicrobial resistance (AMR) development from native microbiomes and the risks associated with chemical exposure is limited. By implementing a lichen asa bioindicatororganism and model for a native microbiome, we systematically examined responses towards antimicrobials (colistin, tetracycline, glyphosate, and alkylpyrazine). Despite an unexpectedly high resilience, we identified potential evolutionary consequences of chemical exposure in terms of composition and functioning of native bacterial communities. Major shifts in bacterial composition were observed due to replacement of naturally abundant taxa; e.g. Chthoniobacterales by Pseudomonadales. A general response, which comprised activation of intrinsic resistance and parallel reduction of metabolic activity at RNA and protein levels was deciphered by a multi-omics approach. Targeted analyses of key taxa based on metagenome-assembled genomes reflected these responses but also revealed diversified strategies of their players. Chemical-specific responses were also observed, e.g., glyphosate enriched bacterial r-strategists and activated distinct ARGs. Our work demonstrates that the high resilience of the native microbiota toward antimicrobial exposure is not only explained by the presence of antibiotic resistance genes but also adapted metabolic activity as a trade-off for survival. Moreover, our results highlight the importance of native microbiomes as important but so far neglected AMR reservoirs. We expect that this phenomenon is representative for a wide range of environmental microbiota exposed to chemicals that potentially contribute to the emergence of antibiotic-resistant bacteria from natural environments.
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Affiliation(s)
- Wisnu Adi Wicaksono
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria.
| | - Maria Braun
- Institute of Microbiology, University of Greifswald, Greifswald, Germany.
| | - Jörg Bernhardt
- Institute of Microbiology, University of Greifswald, Greifswald, Germany.
| | - Katharina Riedel
- Institute of Microbiology, University of Greifswald, Greifswald, Germany.
| | - Tomislav Cernava
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria.
| | - Gabriele Berg
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria; Leibniz-Institute for Agricultural Engineering and Bioeconomy Potsdam (ATB), Potsdam, Germany; Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
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4
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Brauer M, Herrmann J, Zühlke D, Müller R, Riedel K, Sievers S. Myxopyronin B inhibits growth of a Fidaxomicin-resistant Clostridioides difficile isolate and interferes with toxin synthesis. Gut Pathog 2022; 14:4. [PMID: 34991700 PMCID: PMC8739712 DOI: 10.1186/s13099-021-00475-9] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 12/13/2021] [Indexed: 02/06/2023] Open
Abstract
The anaerobic, gastrointestinal pathogen Clostridioides difficile can cause severe forms of enterocolitis which is mainly mediated by the toxins it produces. The RNA polymerase inhibitor Fidaxomicin is the current gold standard for the therapy of C. difficile infections due to several beneficial features including its ability to suppress toxin synthesis in C. difficile. In contrast to the Rifamycins, Fidaxomicin binds to the RNA polymerase switch region, which is also the binding site for Myxopyronin B. Here, serial broth dilution assays were performed to test the susceptibility of C. difficile and other anaerobes to Myxopyronin B, proving that the natural product is considerably active against C. difficile and that there is no cross-resistance between Fidaxomicin and Myxopyronin B in a Fidaxomicin-resistant C. difficile strain. Moreover, mass spectrometry analysis indicated that Myxopyronin B is able to suppress early phase toxin synthesis in C. difficile to the same degree as Fidaxomicin. Conclusively, Myxopyronin B is proposed as a new lead structure for the design of novel antibiotics for the therapy of C. difficile infections.
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Affiliation(s)
- Madita Brauer
- Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Jennifer Herrmann
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI) and Department of Pharmacy, Saarland University, Saarbrücken, Germany.,German Center for Infection Research (DZIF), Braunschweig, Germany
| | - Daniela Zühlke
- Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Rolf Müller
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI) and Department of Pharmacy, Saarland University, Saarbrücken, Germany.,German Center for Infection Research (DZIF), Braunschweig, Germany
| | - Katharina Riedel
- Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Susanne Sievers
- Institute of Microbiology, University of Greifswald, Greifswald, Germany.
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5
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Valencia EY, Barros JP, Ferenci T, Spira B. A Broad Continuum of E. coli Traits in Nature Associated with the Trade-off Between Self-preservation and Nutritional Competence. MICROBIAL ECOLOGY 2022; 83:68-82. [PMID: 33846820 DOI: 10.1007/s00248-021-01751-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
A trade-off between reproduction and survival is a characteristic of many organisms. In bacteria, growth is constrained when cellular resources are channelled towards environmental stress protection. At the core of this trade-off in Escherichia coli is RpoS, a sigma factor that diverts transcriptional resources towards general stress resistance. The constancy of RpoS levels in natural isolates is unknown. A uniform RpoS content in E. coli would impart a narrow range of resistance properties to the species, whereas a diverse set of RpoS levels in nature should result in a diverse range of stress susceptibilities. We explore the diversity of trade-off settings and phenotypes by measuring the level of RpoS protein in strains of E. coli cohabiting in a natural environment. Strains from a stream polluted with domestic waste were investigated in monthly samples. Analyses included E. coli phylogroup classification, RpoS protein level, RpoS-dependent stress phenotypes and the sequencing of rpoS mutations. The most striking finding was the continuum of RpoS levels, with a 100-fold range of RpoS amounts consistently found in individuals in the stream. Approximately 1.8% of the sampled strains carried null or non-synonymous mutations in rpoS. The natural isolates also exhibited a broad (>100-fold) range of stress resistance responses. Our results are consistent with the view that a multiplicity of survival-multiplication trade-off settings is a feature of the species E. coli. The phenotypic diversity resulting from the trade-off permits bet-hedging and the adaptation of E. coli strains to a very broad range of environments.
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Affiliation(s)
- Estela Ynes Valencia
- Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil
| | - Jackeline Pinheiro Barros
- Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil
| | - Thomas Ferenci
- School of Life and Environmental Sciences, University of Sydney, 6/403 Pacific Highway, Sydney, New South Wales, 2070, Australia
| | - Beny Spira
- Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil.
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6
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OmpF Downregulation Mediated by Sigma E or OmpR Activation Confers Cefalexin Resistance in Escherichia coli in the Absence of Acquired β-Lactamases. Antimicrob Agents Chemother 2021; 65:e0100421. [PMID: 34460299 DOI: 10.1128/aac.01004-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cefalexin is a widely used first-generation cephalosporin, and resistance in Escherichia coli is caused by extended-spectrum (e.g., CTX-M) and AmpC β-lactamase production and therefore frequently coincides with third-generation cephalosporin resistance. However, we have recently identified large numbers of E. coli isolates from human infections, and from cattle, where cefalexin resistance is not β-lactamase mediated. Here, we show, by studying laboratory-selected mutants, clinical isolates, and isolates from cattle, that OmpF porin disruption or downregulation is a major cause of cefalexin resistance in E. coli. Importantly, we identify multiple regulatory mutations that cause OmpF downregulation. In addition to mutation of ompR, already known to downregulate OmpF and OmpC porin production, we find that rseA mutation, which strongly activates the sigma E regulon, greatly increases DegP production, which degrades OmpF, OmpC, and OmpA. Furthermore, we reveal that mutations affecting lipopolysaccharide structure, exemplified by the loss of GmhB, essential for lipopolysaccharide heptosylation, also modestly activate DegP production, resulting in OmpF degradation. Remarkably, given the critical importance attached to such systems for normal E. coli physiology, we find evidence for DegP-mediated OmpF downregulation and gmhB and rseA loss-of-function mutation in E. coli isolates derived from human infections. Finally, we show that these regulatory mutations enhance the ability of group 1 CTX-M β-lactamase to confer reduced carbapenem susceptibility, particularly those mutations that cause OmpC in addition to OmpF downregulation.
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7
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Richter R, Lehr CM. Extracellular vesicles as novel assay tools to study cellular interactions of anti-infective compounds - A perspective. Adv Drug Deliv Rev 2021; 173:492-503. [PMID: 33857554 DOI: 10.1016/j.addr.2021.04.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/21/2021] [Accepted: 04/08/2021] [Indexed: 12/13/2022]
Abstract
Sudden outbreaks of novel infectious diseases and the persistent evolution of antimicrobial resistant pathogens make it necessary to develop specific tools to quickly understand pathogen-cell interactions and to study appropriate drug delivery strategies. Extracellular vesicles (EVs) are cell-specific biogenic transport systems, which are gaining more and more popularity as either diagnostic markers or drug delivery systems. Apart from that, there are emerging possibilities for EVs as tools to study drug penetration, drug-membrane interactions as well as pathogen-membrane interactions. However, it appears that the potential of EVs for such applications has not been fully exploited yet. Considering the vast variety of cells that can be involved in an infection, vesicle-based analytical methods are just emerging and the number of reported applications is still relatively small. Aim of this review is to discuss the current state of the art of EV-based assays, especially in the context of antimicrobial research and therapy, and to present some new perspectives for a more exhaustive and creative exploration in the future.
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Affiliation(s)
- Robert Richter
- Department of Drug Delivery Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS) Helmholtz-Centre for Infection Research (HZI), Campus E8.1, 66123 Saarbrücken, Germany
| | - Claus-Michael Lehr
- Department of Drug Delivery Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS) Helmholtz-Centre for Infection Research (HZI), Campus E8.1, 66123 Saarbrücken, Germany; Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
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8
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Khalifa SM, Abd El-Aziz AM, Hassan R, Abdelmegeed ES. β-lactam resistance associated with β-lactamase production and porin alteration in clinical isolates of E. coli and K. pneumoniae. PLoS One 2021; 16:e0251594. [PMID: 34014957 PMCID: PMC8136739 DOI: 10.1371/journal.pone.0251594] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 04/28/2021] [Indexed: 12/23/2022] Open
Abstract
β-lactam resistance represents a worldwide problem and a serious challenge for antimicrobial treatment. Hence this research was conducted to recognize several mechanisms mediating β-lactam resistance in E. coli and K. pneumoniae clinical isolates collected from Mansoura University hospitals, Egypt. A total of 80 isolates, 45 E. coli and 35 K. pneumoniae isolates, were collected and their antibiotic susceptibility was determined by the Disc diffusion method followed by phenotypic and genotypic detection of extended-spectrum β-lactamases (ESBLs), AmpC β-lactamase, carbapenemase enzymes. The outer membrane protein porins of all isolates were analyzed and their genes were examined using gene amplification and sequencing. Also, the resistance to complement-mediated serum killing was estimated. A significant percentage of isolates (93.8%) were multidrug resistance and showed an elevated resistance to β-lactam antibiotics. The presence of either ESBL or AmpC enzymes was high among isolates (83.75%). Also, 60% of the isolated strains were carbapenemase producers. The most frequently detected gene of ESBL among all tested isolates was blaCTX-M-15 (86.3%) followed by blaTEM-1 (81.3%) and blaSHV-1 (35%) while the Amp-C gene was present in 83.75%. For carbapenemase-producing isolates, blaNDM1 was the most common (60%) followed by blaVIM-1 (35%) and blaOXA-48 (13.8%). Besides, 73.3% and 40% of E. coli and K. pneumoniae isolates respectively were serum resistant. Outer membrane protein analysis showed that 93.3% of E. coli and 95.7% of K. pneumoniae isolates lost their porins or showed modified porins. Furthermore, sequence analysis of tested porin genes in some isolates revealed the presence of frameshift mutations that produced truncated proteins of smaller size. β-lactam resistance in K. pneumoniae and E. coli isolates in our hospitals is due to a combination of β-lactamase activity and porin loss/alteration. Hence more restrictions should be applied on β-lactams usage to decrease the emergence of resistant strains.
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Affiliation(s)
- Sara M. Khalifa
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Abeer M. Abd El-Aziz
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
- * E-mail: ,
| | - Ramadan Hassan
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Eman S. Abdelmegeed
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
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9
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Ma P, He LL, Pironti A, Laibinis HH, Ernst CM, Manson AL, Bhattacharyya RP, Earl AM, Livny J, Hung DT. Genetic determinants facilitating the evolution of resistance to carbapenem antibiotics. eLife 2021; 10:e67310. [PMID: 33871353 PMCID: PMC8079144 DOI: 10.7554/elife.67310] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/15/2021] [Indexed: 02/07/2023] Open
Abstract
In this era of rising antibiotic resistance, in contrast to our increasing understanding of mechanisms that cause resistance, our understanding of mechanisms that influence the propensity to evolve resistance remains limited. Here, we identified genetic factors that facilitate the evolution of resistance to carbapenems, the antibiotic of 'last resort', in Klebsiella pneumoniae, the major carbapenem-resistant species. In clinical isolates, we found that high-level transposon insertional mutagenesis plays an important role in contributing to high-level resistance frequencies in several major and emerging carbapenem-resistant lineages. A broader spectrum of resistance-conferring mutations for select carbapenems such as ertapenem also enables higher resistance frequencies and, importantly, creates stepping-stones to achieve high-level resistance to all carbapenems. These mutational mechanisms can contribute to the evolution of resistance, in conjunction with the loss of systems that restrict horizontal resistance gene uptake, such as the CRISPR-Cas system. Given the need for greater antibiotic stewardship, these findings argue that in addition to considering the current efficacy of an antibiotic for a clinical isolate in antibiotic selection, considerations of future efficacy are also important. The genetic background of a clinical isolate and the exact antibiotic identity can and should also be considered as they are determinants of a strain's propensity to become resistant. Together, these findings thus provide a molecular framework for understanding acquisition of carbapenem resistance in K. pneumoniae with important implications for diagnosing and treating this important class of pathogens.
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Affiliation(s)
- Peijun Ma
- The Broad Institute of MIT and HarvardCambridgeUnited States
- Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Department of Genetics, Harvard Medical SchoolBostonUnited States
- Center for Computational and Integrative Biology, Massachusetts General HospitalBostonUnited States
| | - Lorrie L He
- The Broad Institute of MIT and HarvardCambridgeUnited States
| | | | | | - Christoph M Ernst
- The Broad Institute of MIT and HarvardCambridgeUnited States
- Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Department of Genetics, Harvard Medical SchoolBostonUnited States
- Center for Computational and Integrative Biology, Massachusetts General HospitalBostonUnited States
| | | | - Roby P Bhattacharyya
- The Broad Institute of MIT and HarvardCambridgeUnited States
- Division of Infectious Diseases, Massachusetts General HospitalBostonUnited States
| | - Ashlee M Earl
- The Broad Institute of MIT and HarvardCambridgeUnited States
| | - Jonathan Livny
- The Broad Institute of MIT and HarvardCambridgeUnited States
| | - Deborah T Hung
- The Broad Institute of MIT and HarvardCambridgeUnited States
- Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Department of Genetics, Harvard Medical SchoolBostonUnited States
- Center for Computational and Integrative Biology, Massachusetts General HospitalBostonUnited States
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10
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Card KJ, Jordan JA, Lenski RE. Idiosyncratic variation in the fitness costs of tetracycline-resistance mutations in Escherichia coli. Evolution 2021; 75:1230-1238. [PMID: 33634468 DOI: 10.1111/evo.14203] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 02/04/2021] [Accepted: 02/12/2021] [Indexed: 12/15/2022]
Abstract
A bacterium's fitness relative to its competitors, both in the presence and absence of antibiotics, plays a key role in its ecological success and clinical impact. In this study, we examine whether tetracycline-resistant mutants are less fit in the absence of the drug than their sensitive parents, and whether the fitness cost of resistance is constant or variable across independently derived lines. Tetracycline-resistant lines suffered, on average, a reduction in fitness of almost 8%. There was substantial among-line variation in the fitness cost. This variation was not associated with the level of resistance conferred by the mutations, nor did it vary significantly across several genetic backgrounds. The two resistant lines with the most extreme fitness costs involved functionally unrelated mutations on different genetic backgrounds. However, there was also significant variation in the fitness costs for mutations affecting the same pathway and even different alleles of the same gene. Our findings demonstrate that the fitness costs of antibiotic resistance do not always correlate with the phenotypic level of resistance or the underlying genetic changes. Instead, these costs reflect the idiosyncratic effects of particular resistance mutations and the genetic backgrounds in which they occur.
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Affiliation(s)
- Kyle J Card
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, 48824.,Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, Michigan, 48824.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan, 48824
| | - Jalin A Jordan
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan, 48824.,Department of Chemistry, Michigan State University, East Lansing, Michigan, 48824
| | - Richard E Lenski
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, 48824.,Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, Michigan, 48824.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan, 48824
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11
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Zhao Z. Comparison of microbial communities and the antibiotic resistome between prawn mono- and poly-culture systems. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 207:111310. [PMID: 32937228 DOI: 10.1016/j.ecoenv.2020.111310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/01/2020] [Accepted: 09/05/2020] [Indexed: 06/11/2023]
Abstract
Antibiotic resistance genes (ARGs) in mariculture sediments pose a potential risk to public health due to their ability to transfer from environmental bacteria to human pathogens. Long term, this may reduce pathogen susceptibility to antibiotics in medical settings. In recent years, the poly-culture of multiple species has become a popular mariculture approach in China, thanks to its environmental and economic benefits. However, differences in microbial communities and antibiotic resistome between mono- and poly-culture systems are still unclear. In this study, microbial community composition and profiles of entire (microbial DNA) and mobile (plasmid and phage) ARGs in prawn mono- and poly-culture systems were investigated using metagenomics. The abundance of several viruses and human pathogens were enhanced in prawn poly-culture ponds, when compared to monoculture systems. In contrast, sediments from poly-culture systems had a lower diversity and ARG abundance when compared to mono-culture approaches. These ARG variations were predominantly related to mobile genetic elements. Prawn mariculture activities exerted a unique selectivity for ARGs in plasmids, and this selectivity was not influenced by culture methods. The findings of this study have important implications for the selection of mariculture systems in preventing pollution with ARGs.
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Affiliation(s)
- Zelong Zhao
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, Liaoning, PR China.
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12
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Richter R, Kamal M, García-Rivera MA, Kaspar J, Junk M, Elgaher WA, Srikakulam SK, Gress A, Beckmann A, Grißmer A, Meier C, Vielhaber M, Kalinina O, Hirsch AK, Hartmann RW, Brönstrup M, Schneider-Daum N, Lehr CM. A hydrogel-based in vitro assay for the fast prediction of antibiotic accumulation in Gram-negative bacteria. Mater Today Bio 2020; 8:100084. [PMID: 33313504 PMCID: PMC7720078 DOI: 10.1016/j.mtbio.2020.100084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/16/2020] [Accepted: 10/20/2020] [Indexed: 11/30/2022] Open
Abstract
The pipeline of antibiotics has been for decades on an alarmingly low level. Considering the steadily emerging antibiotic resistance, novel tools are needed for early and easy identification of effective anti-infective compounds. In Gram-negative bacteria, the uptake of anti-infectives is especially limited. We here present a surprisingly simple in vitro model of the Gram-negative bacterial envelope, based on 20% (w/v) potato starch gel, printed on polycarbonate 96-well filter membranes. Rapid permeability measurements across this polysaccharide hydrogel allowed to correctly predict either high or low accumulation for all 16 tested anti-infectives in living Escherichia coli. Freeze-fracture TEM supports that the macromolecular network structure of the starch hydrogel may represent a useful surrogate of the Gram-negative bacterial envelope. A random forest analysis of in vitro data revealed molecular mass, minimum projection area, and rigidity as the most critical physicochemical parameters for hydrogel permeability, in agreement with reported structural features needed for uptake into Gram-negative bacteria. Correlating our dataset of 27 antibiotics from different structural classes to reported MIC values of nine clinically relevant pathogens allowed to distinguish active from nonactive compounds based on their low in vitro permeability specifically for Gram-negatives. The model may help to identify poorly permeable antimicrobial candidates before testing them on living bacteria.
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Affiliation(s)
- Robert Richter
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
| | - Mohamed.A.M. Kamal
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Mariel A. García-Rivera
- Department of Chemical Biology, Helmholtz Centre for Infection Research (HZI), 38124 Braunschweig, Germany
| | - Jerome Kaspar
- Institute of Engineering Design, Saarland University, 66123 Saarbrücken, Germany
| | - Maximilian Junk
- Institute of Engineering Design, Saarland University, 66123 Saarbrücken, Germany
| | - Walid A.M. Elgaher
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Sanjay Kumar Srikakulam
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Alexander Gress
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Anja Beckmann
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Alexander Grißmer
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Carola Meier
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Michael Vielhaber
- Institute of Engineering Design, Saarland University, 66123 Saarbrücken, Germany
| | - Olga Kalinina
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Medical Faculty, Saarland University, 66421 Homburg, Germany
| | - Anna K.H. Hirsch
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
| | - Rolf W. Hartmann
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Mark Brönstrup
- Department of Chemical Biology, Helmholtz Centre for Infection Research (HZI), 38124 Braunschweig, Germany
- German Centre for Infection Research (DZIF), 38124 Braunschweig, Germany
| | - Nicole Schneider-Daum
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Claus-Michael Lehr
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
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Global Trends in Proteome Remodeling of the Outer Membrane Modulate Antimicrobial Permeability in Klebsiella pneumoniae. mBio 2020; 11:mBio.00603-20. [PMID: 32291303 PMCID: PMC7157821 DOI: 10.1128/mbio.00603-20] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Klebsiella pneumoniae is a pathogen of humans with high rates of mortality and a recognized global rise in incidence of carbapenem-resistant K. pneumoniae (CRKP). The outer membrane of K. pneumoniae forms a permeability barrier that modulates the ability of antibiotics to reach their intracellular target. OmpK35, OmpK36, OmpK37, OmpK38, PhoE, and OmpK26 are porins in the outer membrane of K. pneumoniae, demonstrated here to have a causative relationship to drug resistance phenotypes in a physiological context. The data highlight that currently trialed combination treatments with a carbapenem and β-lactamase inhibitors could be effective on porin-deficient K. pneumoniae. Together with structural data, the results reveal the role of outer membrane proteome remodeling in antimicrobial resistance of K. pneumoniae and point to the role of extracellular loops, not channel parameters, in drug permeation. This significant finding warrants care in the development of phage therapies for K. pneumoniae infections, given the way porin expression will be modulated to confer phage-resistant—and collateral drug-resistant—phenotypes in K. pneumoniae. In Gram-negative bacteria, the permeability of the outer membrane governs rates of antibiotic uptake and thus the efficacy of antimicrobial treatment. Hydrophilic drugs like β-lactam antibiotics depend on diffusion through pore-forming outer membrane proteins to reach their intracellular targets. In this study, we investigated the distribution of porin genes in more than 2,700 Klebsiella isolates and found a widespread loss of OmpK35 functionality, particularly in those strains isolated from clinical environments. Using a defined set of outer-membrane-remodeled mutants, the major porin OmpK35 was shown to be largely responsible for β-lactam permeation. Sequence similarity network analysis characterized the porin protein subfamilies and led to discovery of a new porin family member, OmpK38. Structure-based comparisons of OmpK35, OmpK36, OmpK37, OmpK38, and PhoE showed near-identical pore frameworks but defining differences in the sequence characteristics of the extracellular loops. Antibiotic sensitivity profiles of isogenic Klebsiella pneumoniae strains, each expressing a different porin as its dominant pore, revealed striking differences in the antibiotic permeability characteristics of each channel in a physiological context. Since K. pneumoniae is a nosocomial pathogen with high rates of antimicrobial resistance and concurrent mortality, these experiments elucidate the role of porins in conferring specific drug-resistant phenotypes in a global context, informing future research to combat antimicrobial resistance in K. pneumoniae.
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Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance. Clin Microbiol Rev 2019; 32:32/4/e00002-19. [PMID: 31315895 DOI: 10.1128/cmr.00002-19] [Citation(s) in RCA: 218] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The genus Enterobacter is a member of the ESKAPE group, which contains the major resistant bacterial pathogens. First described in 1960, this group member has proven to be more complex as a result of the exponential evolution of phenotypic and genotypic methods. Today, 22 species belong to the Enterobacter genus. These species are described in the environment and have been reported as opportunistic pathogens in plants, animals, and humans. The pathogenicity/virulence of this bacterium remains rather unclear due to the limited amount of work performed to date in this field. In contrast, its resistance against antibacterial agents has been extensively studied. In the face of antibiotic treatment, it is able to manage different mechanisms of resistance via various local and global regulator genes and the modulation of the expression of different proteins, including enzymes (β-lactamases, etc.) or membrane transporters, such as porins and efflux pumps. During various hospital outbreaks, the Enterobacter aerogenes and E. cloacae complex exhibited a multidrug-resistant phenotype, which has stimulated questions about the role of cascade regulation in the emergence of these well-adapted clones.
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15
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Abstract
The transport of small molecules across membranes is essential for the import of nutrients and other energy sources into the cell and, for the export of waste and other potentially harmful byproducts out of the cell. While hydrophobic molecules are permeable to membranes, ions and other small polar molecules require transport via specialized membrane transport proteins . The two major classes of membrane transport proteins are transporters and channels. With our focus here on porins-major class of non-specific diffusion channel proteins , we will highlight some recent structural biology reports and functional assays that have substantially contributed to our understanding of the mechanism that mediates uptake of small molecules, including antibiotics, across the outer membrane of Enterobacteriaceae . We will also review advances in the regulation of porin expression and porin biogenesis and discuss these pathways as new therapeutic targets.
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Affiliation(s)
- Muriel Masi
- UMR_MD1, Inserm U1261, IRBA, Membranes et Cibles Thérapeutiques, Facultés de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France
| | | | - Jean-Marie Pagès
- UMR_MD1, Inserm U1261, IRBA, Membranes et Cibles Thérapeutiques, Facultés de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France.
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16
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Temporal dynamics of bacteria-plasmid coevolution under antibiotic selection. ISME JOURNAL 2018; 13:559-562. [PMID: 30209344 PMCID: PMC6330079 DOI: 10.1038/s41396-018-0276-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/13/2018] [Accepted: 08/17/2018] [Indexed: 11/12/2022]
Abstract
Horizontally acquired genes can be costly to express even if they encode useful traits, such as antibiotic resistance. We previously showed that when selected with tetracycline, Escherichia coli carrying the tetracycline-resistance plasmid RK2 evolved mutations on both replicons that together provided increased tetracycline resistance at reduced cost. Here we investigate the temporal dynamics of this intragenomic coevolution. Using genome sequencing we show that the order of adaptive mutations was highly repeatable across three independently evolving populations. Each population first gained a chromosomal mutation in ompF which shortened lag phase and increased tetracycline resistance. This was followed by mutations impairing the plasmid-encoded tetracycline efflux pump, and finally, additional resistance-associated chromosomal mutations. Thus, reducing the cost of the horizontally acquired tetracycline resistance was contingent on first evolving a degree of chromosomally encoded resistance. We conclude therefore that the trajectory of bacteria-plasmid coevolution was constrained to a single repeatable path.
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