1
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Xu J, Abe K, Kodama T, Sultana M, Chac D, Markiewicz SM, Matsunami H, Kuba E, Tsunoda S, Alam M, Weil AA, Nakamura S, Yamashiro T. The role of morphological adaptability in Vibrio cholerae's motility. mBio 2025; 16:e0246924. [PMID: 39611848 PMCID: PMC11708025 DOI: 10.1128/mbio.02469-24] [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: 08/13/2024] [Accepted: 11/12/2024] [Indexed: 11/30/2024] Open
Abstract
Vibrio cholerae, the causative agent of cholera, displays remarkable adaptability to diverse environmental conditions through morphological changes that enhance its pathogenicity and influence the global epidemiology of the disease. This study examines the motility differences between filamentous and comma-shaped forms of the V. cholerae O1 strain under various viscosity conditions. Utilizing the El Tor strain, we induced filamentous transformation and conducted a comparative analysis with the canonical comma-shaped morphology. Our methodology involved assessing motility patterns, swimming speeds, rotation rates, kinematics, and reversal frequencies using dark-field microscopy and high-speed imaging techniques. The results show that filamentous V. cholerae cells retain enhanced motility in viscous environments, indicating an evolutionary adaptation for survival in varied habitats, particularly the human gastrointestinal tract. Filamentous forms exhibited increased reversal behavior at mucin interfaces, suggesting an advantage in penetrating the mucus layer. Furthermore, the presence of filamentous cells in bile-supplemented medium underscores their relevance in natural infection scenarios. IMPORTANCE This study highlights the enhanced motility of filamentous Vibrio cholerae in viscous environments, an adaptation that may provide a survival advantage in the human gastrointestinal tract. By demonstrating increased reversal behavior at mucin interfaces, filamentous V. cholerae cells exhibit a superior ability to penetrate the mucus layer, which is crucial for effective colonization and infection. Filamentous cells in bile-supplemented media further underscores their potential role in disease pathogenesis. These findings offer critical insights into the morphological flexibility of V. cholerae and its potential implications for infection dynamics, paving the way for more effective strategies in managing and preventing cholera outbreaks.
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Affiliation(s)
- Jun Xu
- Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan
| | - Keigo Abe
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan
| | - Toshio Kodama
- Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Marzia Sultana
- Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh, Bangladesh, Dhaka
| | - Denise Chac
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | | | - Hideyuki Matsunami
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology, Okinawa, Japan
| | - Erika Kuba
- Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan
| | - Shiyu Tsunoda
- Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan
| | - Munirul Alam
- Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh, Bangladesh, Dhaka
| | - Ana A. Weil
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Shuichi Nakamura
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan
| | - Tetsu Yamashiro
- Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan
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2
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Campey A, Łapińska U, Chait R, Tsaneva-Atanasova K, Pagliara S. Antibiotic resistant bacteria survive treatment by doubling while shrinking. mBio 2024; 15:e0237524. [PMID: 39565111 PMCID: PMC11633386 DOI: 10.1128/mbio.02375-24] [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: 08/02/2024] [Accepted: 10/22/2024] [Indexed: 11/21/2024] Open
Abstract
Many antibiotics that are used in healthcare, farming, and aquaculture end up in environments with different spatial structures that might promote heterogeneity in the emergence of antibiotic resistance. However, the experimental evolution of microbes at sub-inhibitory concentrations of antibiotics has been mainly carried out at the population level which does not allow capturing single-cell responses to antibiotics. Here, we investigate and compare the emergence of resistance to ciprofloxacin in Escherichia coli in well-mixed and structured environments using experimental evolution, genomics, and microfluidics-based time-lapse microscopy. We discover that resistance to ciprofloxacin and cross-resistance to other antibiotics is stronger in the well-mixed environment due to the emergence of target mutations, whereas efflux regulator mutations emerge in the structured environment. The latter mutants also harbor sub-populations of persisters that survive high concentrations of ciprofloxacin that inhibit bacterial growth at the population level. In contrast, genetically resistant bacteria that display target mutations also survive high concentrations of ciprofloxacin that inhibit their growth via population-level antibiotic tolerance. These resistant and tolerant bacteria keep doubling while shrinking in size in the presence of ciprofloxacin and regain their original size after antibiotic removal, which constitutes a newly discovered phenotypic response. This new knowledge sheds light on the diversity of strategies employed by bacteria to survive antibiotics and poses a stepping stone for understanding the link between mutations at the population level and phenotypic single-cell responses. IMPORTANCE The evolution of antimicrobial resistance poses a pressing challenge to global health with an estimated 5 million deaths associated with antimicrobial resistance every year globally. Here, we investigate the diversity of strategies employed by bacteria to survive antibiotics. We discovered that bacteria evolve genetic resistance to antibiotics while simultaneously displaying tolerance to very high doses of antibiotics by doubling while shrinking in size.
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Affiliation(s)
- Adrian Campey
- Living Systems Institute and Biosciences, University of Exeter, Exeter, Devon, United Kingdom
| | - Urszula Łapińska
- Living Systems Institute and Biosciences, University of Exeter, Exeter, Devon, United Kingdom
| | - Remy Chait
- Living Systems Institute and Biosciences, University of Exeter, Exeter, Devon, United Kingdom
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute and Biosciences, University of Exeter, Exeter, Devon, United Kingdom
- EPSRC Hub for Quantitative Modelling in Healthcare, University of Exeter, Exeter, Devon, United Kingdom
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, Devon, United Kingdom
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3
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Ikeda H, Maeda S. Characterization of Escherichia coli Persisters from Biofilm Culture: Multiple Dormancy Levels and Multigenerational Memory in Formation. Microorganisms 2024; 12:1888. [PMID: 39338564 PMCID: PMC11434456 DOI: 10.3390/microorganisms12091888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2024] [Revised: 09/09/2024] [Accepted: 09/10/2024] [Indexed: 09/30/2024] Open
Abstract
Persister cells (PCs), a subpopulation occurring within normal cells, exhibit a transient tolerance to antibiotics because of their dormant state. PCs are categorized into two types: type I PCs, which emerge during the stationary phase, and type II PCs, which emerge during the logarithmic phase. Using the conventional colony-forming method, we previously demonstrated that type I PCs of Escherichia coli form more frequently in air-solid biofilm culture than in liquid culture. In the current study, we modified a cell filamentation method as a more efficient and rapid alternative for quantifying PCs. This modified method yielded results consistent with those of the conventional method with 103-104 times higher sensitivity and less detection time, within several hours, and further revealed the existence of multiple levels of type I PCs, including a substantial number of deeply dormant cells. This study also discovered a potential epigenetic memory mechanism, spanning several generations (four or six cell divisions), which influences type II PC formation based on prior biofilm experience in E. coli.
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Affiliation(s)
| | - Sumio Maeda
- Graduate School of Humanities and Sciences, Nara Women’s University, Kitauoya-nishimachi, Nara 630-8506, Japan
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4
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Fernández-García L, Song S, Kirigo J, Battisti ME, Petersen ME, Tomás M, Wood TK. Toxin/antitoxin systems induce persistence and work in concert with restriction/modification systems to inhibit phage. Microbiol Spectr 2024; 12:e0338823. [PMID: 38054715 PMCID: PMC10783111 DOI: 10.1128/spectrum.03388-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 11/06/2023] [Indexed: 12/07/2023] Open
Abstract
IMPORTANCE To date, there are no reports of phage infection-inducing persistence. Therefore, our results are important since we show for the first time that a phage-defense system, the MqsRAC toxin/antitoxin system, allows the host to survive infection by forming persister cells, rather than inducing cell suicide. Moreover, we demonstrate that the MqsRAC system works in concert with restriction/modification systems. These results imply that if phage therapy is to be successful, anti-persister compounds need to be administered along with phages.
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Affiliation(s)
- Laura Fernández-García
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
- Microbiology Department of Hospital A Coruña (CHUAC), Microbiology Translational and Multidisciplinary (MicroTM)-Research Institute Biomedical A Coruña (INIBIC) and University of A Coruña (UDC), A Coruña, Spain
| | - Sooyeon Song
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Animal Science, Jeonbuk National University, Jeonju-Si, Jellabuk-Do, South Korea
- Agricultural Convergence Technology, Jeonbuk National University, Jeonju-Si, Jellabuk-Do, South Korea
| | - Joy Kirigo
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Michael E. Battisti
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Maiken E. Petersen
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - María Tomás
- Microbiology Department of Hospital A Coruña (CHUAC), Microbiology Translational and Multidisciplinary (MicroTM)-Research Institute Biomedical A Coruña (INIBIC) and University of A Coruña (UDC), A Coruña, Spain
| | - Thomas K. Wood
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
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5
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Zhao X, Ruelens P, Farr AD, de Visser JAGM, Baraban L. Population dynamics of cross-protection against β-lactam antibiotics in droplet microreactors. Front Microbiol 2023; 14:1294790. [PMID: 38192289 PMCID: PMC10773670 DOI: 10.3389/fmicb.2023.1294790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 12/06/2023] [Indexed: 01/10/2024] Open
Abstract
Introduction Bacterial strains that are resistant to antibiotics may protect not only themselves, but also sensitive bacteria nearby if resistance involves antibiotic degradation. Such cross-protection poses a challenge to effective antibiotic therapy by enhancing the long-term survival of bacterial infections, however, the current understanding is limited. Methods In this study, we utilize an automated nanoliter droplet analyzer to study the interactions between Escherichia coli strains expressing a β-lactamase (resistant) and those not expressing it (sensitive) when exposed to the β-lactam antibiotic cefotaxime (CTX), with the aim to define criteria contributing to cross-protection. Results We observed a cross-protection window of CTX concentrations for the sensitive strain, extending up to approximately 100 times its minimal inhibitory concentration (MIC). Through both microscopy and enzyme activity analyses, we demonstrate that bacterial filaments, triggered by antibiotic stress, contribute to cross-protection. Discussion The antibiotic concentration window for cross-protection depends on the difference in β-lactamase activity between co-cultured strains: larger differences shift the 'cross-protection window' toward higher CTX concentrations. Our findings highlight the dependence of opportunities for cross-protection on the relative resistance levels of the strains involved and suggest a possible specific role for filamentation.
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Affiliation(s)
- Xinne Zhao
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf e. V. (HZDR), Dresden, Germany
| | - Philip Ruelens
- Laboratory of Genetics, Wageningen University and Research, Wageningen, Netherlands
| | - Andrew D. Farr
- Laboratory of Genetics, Wageningen University and Research, Wageningen, Netherlands
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | | | - Larysa Baraban
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf e. V. (HZDR), Dresden, Germany
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6
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Pan X, Liu W, Du Q, Zhang H, Han D. Recent Advances in Bacterial Persistence Mechanisms. Int J Mol Sci 2023; 24:14311. [PMID: 37762613 PMCID: PMC10531727 DOI: 10.3390/ijms241814311] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
The recurrence of bacterial infectious diseases is closely associated with bacterial persisters. This subpopulation of bacteria can escape antibiotic treatment by entering a metabolic status of low activity through various mechanisms, for example, biofilm, toxin-antitoxin modules, the stringent response, and the SOS response. Correspondingly, multiple new treatments are being developed. However, due to their spontaneous low abundance in populations and the lack of research on in vivo interactions between persisters and the host's immune system, microfluidics, high-throughput sequencing, and microscopy techniques are combined innovatively to explore the mechanisms of persister formation and maintenance at the single-cell level. Here, we outline the main mechanisms of persister formation, and describe the cutting-edge technology for further research. Despite the significant progress regarding study techniques, some challenges remain to be tackled.
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Affiliation(s)
- Xiaozhou Pan
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Wenxin Liu
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Qingqing Du
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Hong Zhang
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Dingding Han
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
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7
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Fernández-García L, Tomás M, Wood TK. Ribosome inactivation by Escherichia coli GTPase RsgA inhibits T4 phage. Front Microbiol 2023; 14:1242163. [PMID: 37670987 PMCID: PMC10475562 DOI: 10.3389/fmicb.2023.1242163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 08/07/2023] [Indexed: 09/07/2023] Open
Abstract
Introduction Bacteria must combat phages, and myriad bacterial anti-phage systems have been discovered that reduce host metabolism, for example, by depleting energetic compounds like ATP and NAD+. Hence, these systems indirectly inhibit protein production. Surprisingly, direct reduction of ribosome activity has not been demonstrated to thwart phage. Methods Here, by producing each of the 4,287 Escherichia coli proteins and selecting for anti-phage activity that leads to enhanced growth, we investigated the role of host proteins in phage inhibition. Results and discussion We identified that E. coli GTPase RsgA inhibits lytic phage T4 by inactivating ribosomes.
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Affiliation(s)
- Laura Fernández-García
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
- Microbiology Translational and Multidisciplinary (MicroTM)-Research Institute Biomedical A Coruña (INIBIC) and Microbiology Department of Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
| | - María Tomás
- Microbiology Translational and Multidisciplinary (MicroTM)-Research Institute Biomedical A Coruña (INIBIC) and Microbiology Department of Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
| | - Thomas K. Wood
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
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8
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Bollen C, Louwagie E, Verstraeten N, Michiels J, Ruelens P. Environmental, mechanistic and evolutionary landscape of antibiotic persistence. EMBO Rep 2023; 24:e57309. [PMID: 37395716 PMCID: PMC10398667 DOI: 10.15252/embr.202357309] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/07/2023] [Accepted: 06/16/2023] [Indexed: 07/04/2023] Open
Abstract
Recalcitrant infections pose a serious challenge by prolonging antibiotic therapies and contributing to the spread of antibiotic resistance, thereby threatening the successful treatment of bacterial infections. One potential contributing factor in persistent infections is antibiotic persistence, which involves the survival of transiently tolerant subpopulations of bacteria. This review summarizes the current understanding of antibiotic persistence, including its clinical significance and the environmental and evolutionary factors at play. Additionally, we discuss the emerging concept of persister regrowth and potential strategies to combat persister cells. Recent advances highlight the multifaceted nature of persistence, which is controlled by deterministic and stochastic elements and shaped by genetic and environmental factors. To translate in vitro findings to in vivo settings, it is crucial to include the heterogeneity and complexity of bacterial populations in natural environments. As researchers continue to gain a more holistic understanding of this phenomenon and develop effective treatments for persistent bacterial infections, the study of antibiotic persistence is likely to become increasingly complex.
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Affiliation(s)
- Celien Bollen
- Centre of Microbial and Plant GeneticsKU LeuvenLeuvenBelgium
- Center for Microbiology, VIBLeuvenBelgium
| | - Elen Louwagie
- Centre of Microbial and Plant GeneticsKU LeuvenLeuvenBelgium
- Center for Microbiology, VIBLeuvenBelgium
| | - Natalie Verstraeten
- Centre of Microbial and Plant GeneticsKU LeuvenLeuvenBelgium
- Center for Microbiology, VIBLeuvenBelgium
| | - Jan Michiels
- Centre of Microbial and Plant GeneticsKU LeuvenLeuvenBelgium
- Center for Microbiology, VIBLeuvenBelgium
| | - Philip Ruelens
- Centre of Microbial and Plant GeneticsKU LeuvenLeuvenBelgium
- Center for Microbiology, VIBLeuvenBelgium
- Laboratory of Socioecology and Social EvolutionKU LeuvenLeuvenBelgium
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9
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Zhang Y, Kepiro I, Ryadnov MG, Pagliara S. Single Cell Killing Kinetics Differentiate Phenotypic Bacterial Responses to Different Antibacterial Classes. Microbiol Spectr 2023; 11:e0366722. [PMID: 36651776 PMCID: PMC9927147 DOI: 10.1128/spectrum.03667-22] [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: 09/09/2022] [Accepted: 12/19/2022] [Indexed: 01/19/2023] Open
Abstract
With the spread of multidrug-resistant bacteria, there has been an increasing focus on molecular classes that have not yet yielded an antibiotic. A key capability for assessing and prescribing new antibacterial treatments is to compare the effects antibacterial agents have on bacterial growth at a phenotypic, single-cell level. Here, we combined time-lapse microscopy with microfluidics to investigate the concentration-dependent killing kinetics of stationary-phase Escherichia coli cells. We used antibacterial agents from three different molecular classes, β-lactams and fluoroquinolones, with the known antibiotics ampicillin and ciprofloxacin, respectively, and a new experimental class, protein Ψ-capsids. We found that bacterial cells elongated when treated with ampicillin and ciprofloxacin used at their minimum inhibitory concentration (MIC). This was in contrast to Ψ-capsids, which arrested bacterial elongation within the first two hours of treatment. At concentrations exceeding the MIC, all the antibacterial agents tested arrested bacterial growth within the first 2 h of treatment. Further, our single-cell experiments revealed differences in the modes of action of three different agents. At the MIC, ampicillin and ciprofloxacin caused the lysis of bacterial cells, whereas at higher concentrations, the mode of action shifted toward membrane disruption. The Ψ-capsids killed cells by disrupting their membranes at all concentrations tested. Finally, at increasing concentrations, ampicillin and Ψ-capsids reduced the fraction of the population that survived treatment in a viable but nonculturable state, whereas ciprofloxacin increased this fraction. This study introduces an effective capability to differentiate the killing kinetics of antibacterial agents from different molecular classes and offers a high content analysis of antibacterial mechanisms at the single-cell level. IMPORTANCE Antibiotics act against bacterial pathogens by inhibiting their growth or killing them directly. Different modes of action determine different antibacterial responses, whereas phenotypic differences in bacteria can challenge the efficacy of antibiotics. Therefore, it is important to be able to differentiate the concentration-dependent killing kinetics of antibacterial agents at a single-cell level, in particular for molecular classes which have not yielded an antibiotic before. Here, we measured single-cell responses using microfluidics-enabled imaging, revealing that a novel class of antibacterial agents, protein Ψ-capsids, arrests bacterial elongation at the onset of treatment, whereas elongation continues for cells treated with β-lactam and fluoroquinolone antibiotics. The study advances our current understanding of antibacterial function and offers an effective strategy for the comparative design of new antibacterial therapies, as well as clinical antibiotic susceptibility testing.
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Affiliation(s)
- Yuewen Zhang
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
- National Physical Laboratory, Teddington, United Kingdom
| | - Ibolya Kepiro
- National Physical Laboratory, Teddington, United Kingdom
| | - Maxim G. Ryadnov
- National Physical Laboratory, Teddington, United Kingdom
- Department of Physics, King’s College London, London, United Kingdom
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
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10
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Yu Z, Goodall ECA, Henderson IR, Guo J. Plasmids Can Shift Bacterial Morphological Response against Antibiotic Stress. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2203260. [PMID: 36424175 PMCID: PMC9839882 DOI: 10.1002/advs.202203260] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 09/17/2022] [Indexed: 06/16/2023]
Abstract
Bacterial cell filamentation is a morphological change wherein cell division is blocked, which can improve bacterial survival under unfavorable conditions (e.g., antibiotic stress that causes DNA damage). As an extrachromosomal DNA molecule, plasmids can confer additionally advantageous traits including antibiotic resistance on the host. However, little is known about whether plasmids could shift bacterial morphological responses to antibiotic stress. Here, it is reported that plasmid-free cells, rather than plasmid-bearing cells, exhibit filamentation and asymmetrical cell division under exposure to sub-inhibitory concentrations of antibiotics (ciprofloxacin and cephalexin). The underlying mechanism is revealed by investigating DNA damage, cell division inhibitor sulA, the SOS response, toxin-antitoxin module (parDE) located on plasmids, and efflux pumps. Significantly higher expression of sulA is observed in plasmid-free cells, compared to plasmid-bearing cells. Plasmid carriage enables the hosts to suffer less DNA damage, exhibit stronger efflux pump activities, and thus have a higher antibiotic tolerance. These benefits are attributed to the parDE module that mediates stress responses from plasmid-bearing cells and mainly contributes to cell morphological changes. Collectively, the findings demonstrate that plasmids can confer additional innate defenses on the host to antibiotics, thus advancing the understanding of how plasmids affect bacterial evolution in hostile environments.
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Affiliation(s)
- Zhigang Yu
- Australian Centre for Water and Environmental BiotechnologyThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
| | - Emily C. A. Goodall
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
| | - Ian R. Henderson
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
| | - Jianhua Guo
- Australian Centre for Water and Environmental BiotechnologyThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
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11
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Mechanistic Insights to Combating NDM- and CTX-M-Coproducing Klebsiella pneumoniae by Targeting Cell Wall Synthesis and Outer Membrane Integrity. Antimicrob Agents Chemother 2022; 66:e0052722. [PMID: 35924913 PMCID: PMC9487485 DOI: 10.1128/aac.00527-22] [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] [Indexed: 02/06/2023] Open
Abstract
Metallo-β-lactamase (MBL)-producing Gram-negative bacteria cause infections associated with high rates of morbidity and mortality. Currently, a leading regimen to treat infections caused by MBL-producing bacteria is aztreonam combined with ceftazidime-avibactam. The purpose of the present study was to evaluate and rationally optimize the combination of aztreonam and ceftazidime-avibactam with and without polymyxin B against a clinical Klebsiella pneumoniae isolate producing NDM-1 and CTX-M by use of the hollow fiber infection model (HFIM). A novel de-escalation approach to polymyxin B dosing was also explored, whereby a standard 0-h loading dose was followed by maintenance doses that were 50% of the typical clinical regimen. In the HFIM, the addition of polymyxin B to aztreonam plus ceftazidime-avibactam significantly improved bacterial killing, leading to eradication, including for the novel de-escalation dosing strategy. Serial samples from the growth control and monotherapies were explored in a Galleria mellonella virulence model to assess virulence changes. Weibull regression showed that low-level ceftazidime resistance and treatment with monotherapy resulted in increased G. mellonella mortality (P < 0.05). A neutropenic rabbit pneumonia model demonstrated that aztreonam plus ceftazidime-avibactam with or without polymyxin B resulted in similar bacterial killing, and these combination therapies were statistically significantly better than monotherapies (P < 0.05). However, only the polymyxin B-containing combination therapy produced a statistically significant decrease in lung weights (P < 0.05), indicating a decreased inflammatory process. Altogether, adding polymyxin B to the combination of aztreonam plus ceftazidime-avibactam for NDM- and CTX-M-producing K. pneumoniae improved bacterial killing effects, reduced lung inflammation, suppressed resistance amplification, and limited virulence changes.
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12
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Wilmaerts D, Govers SK, Michiels J. Assessing persister awakening dynamics following antibiotic treatment in E. coli. STAR Protoc 2022; 3:101476. [PMID: 35769931 PMCID: PMC9234080 DOI: 10.1016/j.xpro.2022.101476] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Given the low fraction of antibiotic-tolerant persisters and the transient nature of the persister phenotype, identifying molecular mechanisms underlying persister state exit, also called "awakening," is challenging. Here, we describe how persister awakening kinetics can be quantified at the single-cell level, enabling the identification of genes that are important for persister survival following antibiotic treatment. We report step-by-step sample preparation, dynamic recording, and data analysis. Although the setup is flexible, time-lapse microscopy requires a minimal number of persisters being present. For complete details on the use and execution of this protocol, please refer to Wilmaerts et al. (2022). Protocol for assessing persister awakening dynamics via time-lapse microscopy Experimental procedures and explanation on how to identify persisters Guidelines on analyses and interpretation of awakening kinetics
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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13
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Edelmann D, Berghoff BA. A Shift in Perspective: A Role for the Type I Toxin TisB as Persistence-Stabilizing Factor. Front Microbiol 2022; 13:871699. [PMID: 35369430 PMCID: PMC8969498 DOI: 10.3389/fmicb.2022.871699] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Bacterial persistence is a phenomenon that is founded by the existence of a subpopulation of multidrug-tolerant cells. These so-called persister cells endure otherwise lethal stress situations and enable restoration of bacterial populations upon return to favorable conditions. Persisters are especially notorious for their ability to survive antibiotic treatments without conventional resistance genes and to cause infection relapse. The persister state is typically correlated with reduction or inhibition of cellular activity. Early on, chromosomal toxin-antitoxin (TA) systems were suspected to induce the persister state in response to environmental stress. However, this idea has been challenged during the last years. Especially the involvement of toxins from type II TA systems in persister formation is put into question. For toxins from type I TA systems the debate has just started. Here, we would like to summarize recent knowledge gained for the type I TA system tisB/istR-1 from Escherichia coli. TisB is a small, membrane-targeting toxin, which disrupts the proton motive force (PMF), leading to membrane depolarization. Based on experimental data, we hypothesize that TisB primarily stabilizes the persister state through depolarization and further, secondary effects. We will present a simple model that will provide a framework for future directions.
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Mohiuddin SG, Massahi A, Orman MA. High-Throughput Screening of a Promoter Library Reveals New Persister Mechanisms in Escherichia Coli. Microbiol Spectr 2022; 10:e0225321. [PMID: 35196813 PMCID: PMC8865558 DOI: 10.1128/spectrum.02253-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 01/31/2022] [Indexed: 11/23/2022] Open
Abstract
Persister cells are a small subpopulation of phenotypic variants that survive high concentrations of bactericidal antibiotics. Their survival mechanisms are not heritable and can be formed stochastically or triggered by environmental stresses such as antibiotic treatment. In this study, high-throughput screening of an Escherichia coli promoter library and subsequent validation experiments identified several genes whose expression was upregulated by antibiotic treatment. Among the identified genes, waaG, guaA, and guaB were found to be important in persister cell formation in E. coli as their deletion significantly enhanced the sensitivity of cells to various antibiotics. The GuaA and GuaB enzymes form the upstream reactions of ppGpp (a global persister molecule) biosynthesis, and the deletion of guaA and guaB drastically perturbs the ppGpp regulon in E. coli. WaaG, a lipopolysaccharide glucosyltransferase, plays an important role in shaping the outer membrane structure, and the deletion of waaG dissipates the proton gradient (ΔpH) component of cellular proton motive force (PMF), perturbs cellular ATP production, and reduces type I persister formation in stationary phase. Active respiration in the stationary phase, which drives the PMF, was previously shown to play a critical role in type I persister formation, and our results associated with the waaG deficient strain further corroborate these findings. IMPORTANCE Persistence is a nonheritable trait by which normal growing cells switch phenotypically to antibiotic tolerant persister cells. This transient state enables persister cells to recover and grow into an antibiotic-sensitive population. Persister cells have been observed in many pathogenic and nonpathogenic bacteria. Previous studies highlight the complexity and diversity of bacterial persister-cell mechanisms, many of which still remain to be elucidated. Here, using promoter and knockout cell libraries in Escherichia coli, we have identified genes that reveal novel persister mechanisms. As persistence is a critical survival strategy that evolved in many bacteria, our study will enhance the current molecular-level understanding of this conserved mechanism.
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Affiliation(s)
- Sayed Golam Mohiuddin
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
| | - Aslan Massahi
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
| | - Mehmet A. Orman
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, USA
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15
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Abstract
Bacterial persisters are nongrowing cells highly tolerant to bactericidal antibiotics. However, this tolerance is reversible and not mediated by heritable genetic changes. Lon, an ATP-dependent protease, has repeatedly been shown to play a critical role in fluoroquinolone persistence in Escherichia coli. Although lon deletion (Δlon) is thought to eliminate persister cells via accumulation of the cell division inhibitor protein SulA, the exact mechanism underlying this phenomenon is not yet elucidated. Here, we show that Lon is an important regulatory protein for the resuscitation of the fluoroquinolone persisters in E. coli, and lon deletion impairs the ability of persister cells to form colonies during recovery through a sulA- and ftsZ-dependent mechanism. Notably, this observed "viable but nonculturable" state of antibiotic-tolerant Δlon cells is transient, as environmental conditions, such as starvation, can restore their culturability. Our data further indicate that starvation-induced SulA degradation or expression of Lon during recovery facilitates Z-ring formation in Δlon persisters, and Z-ring architecture is important for persister resuscitation in both wild-type and Δlon strains. Our in-depth image analysis clearly shows that the ratio of cell length to number of FtsZ rings for each intact ofloxacin-treated cell predicts the probability of resuscitation and, hence, can be used as a potential biomarker for persisters. IMPORTANCE The ATP-dependent Lon protease is one of the most studied bacterial proteases. Although deletion of lon has been frequently shown to reduce fluoroquinolone persistence, the proposed mechanisms underlying this phenomenon are highly controversial. Here, we have shown that lon deletion in Escherichia coli impairs the ability of persister cells to form colonies during recovery and that this reduction of persister levels in lon-deficient cells can be transient. We also found that altered Z-ring architecture is a key biomarker in both wild-type and lon-deficient persister cells transitioning to a normal cell state. Collectively, our findings highlight the importance of differentiating persister formation mechanisms from resuscitation mechanisms and underscore the critical role of the nonculturable cell state in antibiotic tolerance.
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16
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Karasz DC, Weaver AI, Buckley DH, Wilhelm RC. Conditional filamentation as an adaptive trait of bacteria and its ecological significance in soils. Environ Microbiol 2021; 24:1-17. [PMID: 34929753 DOI: 10.1111/1462-2920.15871] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/03/2021] [Accepted: 12/07/2021] [Indexed: 11/30/2022]
Abstract
Bacteria can regulate cell morphology in response to environmental conditions, altering their physiological and metabolic characteristics to improve survival. Conditional filamentation, in which cells suspend division while continuing lateral growth, is a strategy with a range of adaptive benefits. Here, we review the causes and consequences of conditional filamentation with respect to bacterial physiology, ecology and evolution. We describe four major benefits from conditional filamentation: stress tolerance, surface colonization, gradient spanning and the facilitation of biotic interactions. Adopting a filamentous growth habit involves fitness trade-offs which are also examined. We focus on the role of conditional filamentation in soil habitats, where filamentous morphotypes are highly prevalent and where environmental heterogeneity can benefit a conditional response. To illustrate the use of information presented in our review, we tested the conditions regulating filamentation by the forest soil isolate Paraburkholderia elongata 5NT . Filamentation by P. elongata was induced at elevated phosphate concentrations, and was associated with the accumulation of intracellular polyphosphate, highlighting the role of filamentation in a phosphate-solubilizing bacterium. Conditional filamentation enables bacteria to optimize their growth and metabolism in environments that are highly variable, a trait that can impact succession, symbioses, and biogeochemistry in soil environments.
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Affiliation(s)
- David C Karasz
- School of Integrative Plant Science, Bradfield Hall, Cornell University, Ithaca, New York, 14853, USA
| | - Anna I Weaver
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, New York, 14853, USA.,Weill Institute for Cell and Molecular Biology, Weill Hall, Cornell University, Ithaca, New York, 14853, USA
| | - Daniel H Buckley
- School of Integrative Plant Science, Bradfield Hall, Cornell University, Ithaca, New York, 14853, USA
| | - Roland C Wilhelm
- School of Integrative Plant Science, Bradfield Hall, Cornell University, Ithaca, New York, 14853, USA
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17
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Svenningsen MS, Svenningsen SL, Sørensen MA, Mitarai N. Existence of log-phase Escherichia coli persisters and lasting memory of a starvation pulse. Life Sci Alliance 2021; 5:5/2/e202101076. [PMID: 34795016 PMCID: PMC8605324 DOI: 10.26508/lsa.202101076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 11/24/2022] Open
Abstract
The authors characterize the growth condition dependence of survival of bacteria exposed to lethal antibiotics for a week. 1-h starvation pulse is shown to cause an increase in survival for days. The vast majority of a bacterial population is killed when treated with a lethal concentration of antibiotics. The time scale of this killing is often comparable with the bacterial generation time before the addition of antibiotics. Yet, a small subpopulation typically survives for an extended period. However, the long-term killing dynamics of bacterial cells has not been fully quantified even in well-controlled laboratory conditions. We constructed a week-long killing assay and followed the survival fraction of Escherichia coli K12 exposed to a high concentration of ciprofloxacin. We found that long-term survivors were formed during exponential growth, with some cells surviving at least 7 d. The long-term dynamics contained at least three time scales, which greatly enhances predictions of the population survival time compared with the biphasic extrapolation from the short-term behavior. Furthermore, we observed a long memory effect of a brief starvation pulse, which was dependent on the (p)ppGpp synthase relA. Specifically, 1 h of carbon starvation before antibiotics exposure increased the surviving fraction by nearly 100-fold even after 4 d of ciprofloxacin treatment.
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Affiliation(s)
| | | | | | - Namiko Mitarai
- The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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18
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Enrichment of Persister Cells Through Β-Lactam-Induced Filamentation and Size Separation. Methods Mol Biol 2021. [PMID: 34590251 DOI: 10.1007/978-1-0716-1621-5_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Analyzing persisters at the single-cell level is crucial to properly define their phenotypic traits. However, single-cell analyses are challenging due to the rare and temporary nature of persister cells, thus requiring their rapid and efficient enrichment in a culture. Existing methods to isolate persisters from a bacterial population show important shortcomings, including contamination with susceptible cells and/or cell debris, which complicate subsequent microscopic analyses. We here describe a protocol to enrich persisters in a culture using β-lactam-induced filamentation followed by size separation. This protocol minimizes the amount of cell debris in the final sample, facilitating single-cell studies of persister cells.
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19
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Liu S, Brul S, Zaat SAJ. Isolation of Persister Cells of Bacillus subtilis and Determination of Their Susceptibility to Antimicrobial Peptides. Int J Mol Sci 2021; 22:10059. [PMID: 34576222 PMCID: PMC8470456 DOI: 10.3390/ijms221810059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 12/15/2022] Open
Abstract
Persister cells are growth-arrested subpopulations that can survive possible fatal environments and revert to wild types after stress removal. Clinically, persistent pathogens play a key role in antibiotic therapy failure, as well as chronic, recurrent, and antibiotic-resilient infections. In general, molecular and physiological research on persister cells formation and compounds against persister cells are much desired. In this study, we firstly demonstrated that the spore forming Gram-positive model organism Bacillus subtilis can be used to generate persister cells during exposure to antimicrobial compounds. Interestingly, instead of exhibiting a unified antibiotic tolerance profile, different number of persister cells and spores were quantified in various stress conditions. qPCR results also indicated that differential stress responses are related to persister formation in various environmental conditions. We propose, for the first time to the best of our knowledge, an effective method to isolate B. subtilis persister cells from a population using fluorescence-activated cell sorting (FACS), which makes analyzing persister populations feasible. Finally, we show that alpha-helical cationic antimicrobial peptides SAAP-148 and TC-19, derived from human cathelicidin LL-37 and human thrombocidin-1, respectively, have high efficiency against both B. subtilis vegetative cells and persisters, causing membrane permeability and fluidity alteration. In addition, we confirm that in contrast to persister cells, dormant B. subtilis spores are not susceptible to the antimicrobial peptides.
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Affiliation(s)
- Shiqi Liu
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands;
| | - Stanley Brul
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands;
| | - Sebastian A. J. Zaat
- Centre for Infection and Immunity Amsterdam (CINIMA), Academic Medical Centre, Department of Medical Microbiology, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
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20
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Power AL, Barber DG, Groenhof SRM, Wagley S, Liu P, Parker DA, Love J. The Application of Imaging Flow Cytometry for Characterisation and Quantification of Bacterial Phenotypes. Front Cell Infect Microbiol 2021; 11:716592. [PMID: 34368019 PMCID: PMC8335544 DOI: 10.3389/fcimb.2021.716592] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/08/2021] [Indexed: 12/25/2022] Open
Abstract
Bacteria modify their morphology in response to various factors including growth stage, nutrient availability, predation, motility and long-term survival strategies. Morphological changes may also be associated with specific physiological phenotypes such as the formation of dormant or persister cells in a “viable but non-culturable” (VBNC) state which frequently display different shapes and size compared to their active counterparts. Such dormancy phenotypes can display various degrees of tolerance to antibiotics and therefore a detailed understanding of these phenotypes is crucial for combatting chronic infections and associated diseases. Cell shape and size are therefore more than simple phenotypic characteristics; they are important physiological properties for understanding bacterial life-strategies and pathologies. However, quantitative studies on the changes to cell morphologies during bacterial growth, persister cell formation and the VBNC state are few and severely constrained by current limitations in the most used investigative techniques of flow cytometry (FC) and light or electron microscopy. In this study, we applied high-throughput Imaging Flow Cytometry (IFC) to characterise and quantify, at single-cell level and over time, the phenotypic heterogeneity and morphological changes in cultured populations of four bacterial species, Bacillus subtilis, Lactiplantibacillus plantarum, Pediococcus acidilactici and Escherichia coli. Morphologies in relation to growth stage and stress responses, cell integrity and metabolic activity were analysed. Additionally, we were able to identify and morphologically classify dormant cell phenotypes such as VBNC cells and monitor the resuscitation of persister cells in Escherichia coli following antibiotic treatment. We therefore demonstrate that IFC, with its high-throughput data collection and image capture capabilities, provides a platform by which a detailed understanding of changes in bacterial phenotypes and their physiological implications may be accurately monitored and quantified, leading to a better understanding of the role of phenotypic heterogeneity in the dynamic microbiome.
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Affiliation(s)
- Ann L Power
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Daniel G Barber
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Sophie R M Groenhof
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Sariqa Wagley
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Ping Liu
- Shell International Exploration & Production Inc., Westhollow Technology Center, Houston, TX, United States
| | - David A Parker
- Shell International Exploration & Production Inc., Westhollow Technology Center, Houston, TX, United States
| | - John Love
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
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21
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Revealing Antibiotic Tolerance of the Mycobacterium smegmatis Xanthine/Uracil Permease Mutant Using Microfluidics and Single-Cell Analysis. Antibiotics (Basel) 2021; 10:antibiotics10070794. [PMID: 34209966 PMCID: PMC8300736 DOI: 10.3390/antibiotics10070794] [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: 05/15/2021] [Revised: 06/16/2021] [Accepted: 06/23/2021] [Indexed: 11/26/2022] Open
Abstract
To reveal rare phenotypes in bacterial populations, conventional microbiology tools should be advanced to generate rapid, quantitative, accurate, and high-throughput data. The main drawbacks of widely used traditional methods for antibiotic studies include low sampling rate and averaging data for population measurements. To overcome these limitations, microfluidic-microscopy systems have great promise to produce quantitative single-cell data with high sampling rates. Using Mycobacterium smegmatis cells, we applied both conventional assays and a microfluidic-microscopy method to reveal the antibiotic tolerance mechanisms of wild-type and msm2570::Tn mutant cells. Our results revealed that the enhanced antibiotic tolerance mechanism of the msm2570::Tn mutant was due to the low number of lysed cells during the antibiotic exposure compared to wild-type cells. This is the first study to characterize the antibiotic tolerance phenotype of the msm2570::Tn mutant, which has a transposon insertion in the msm2570 gene—encoding a putative xanthine/uracil permease, which functions in the uptake of nitrogen compounds during nitrogen limitation. The experimental results indicate that the msm2570::Tn mutant can be further interrogated to reveal antibiotic killing mechanisms, in particular, antibiotics that target cell wall integrity.
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22
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Manuse S, Shan Y, Canas-Duarte SJ, Bakshi S, Sun WS, Mori H, Paulsson J, Lewis K. Bacterial persisters are a stochastically formed subpopulation of low-energy cells. PLoS Biol 2021; 19:e3001194. [PMID: 33872303 PMCID: PMC8084331 DOI: 10.1371/journal.pbio.3001194] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 04/29/2021] [Accepted: 03/18/2021] [Indexed: 11/19/2022] Open
Abstract
Persisters represent a small subpopulation of non- or slow-growing bacterial cells that are tolerant to killing by antibiotics. Despite their prominent role in the recalcitrance of chronic infections to antibiotic therapy, the mechanism of their formation has remained elusive. We show that sorted cells of Escherichia coli with low levels of energy-generating enzymes are better able to survive antibiotic killing. Using microfluidics time-lapse microscopy and a fluorescent reporter for in vivo ATP measurements, we find that a subpopulation of cells with a low level of ATP survives killing by ampicillin. We propose that these low ATP cells are formed stochastically as a result of fluctuations in the abundance of energy-generating components. These findings point to a general "low energy" mechanism of persister formation.
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Affiliation(s)
- Sylvie Manuse
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Yue Shan
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Silvia J. Canas-Duarte
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Somenath Bakshi
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Wei-Sheng Sun
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Hirotada Mori
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Johan Paulsson
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Kim Lewis
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
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23
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Cronenberg T, Hennes M, Wielert I, Maier B. Antibiotics modulate attractive interactions in bacterial colonies affecting survivability under combined treatment. PLoS Pathog 2021; 17:e1009251. [PMID: 33524048 PMCID: PMC7877761 DOI: 10.1371/journal.ppat.1009251] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 02/11/2021] [Accepted: 12/21/2020] [Indexed: 02/02/2023] Open
Abstract
Biofilm formation protects bacteria from antibiotics. Very little is known about the response of biofilm-dwelling bacteria to antibiotics at the single cell level. Here, we developed a cell-tracking approach to investigate how antibiotics affect structure and dynamics of colonies formed by the human pathogen Neisseria gonorrhoeae. Antibiotics targeting different cellular functions enlarge the cell volumes and modulate within-colony motility. Focusing on azithromycin and ceftriaxone, we identify changes in type 4 pilus (T4P) mediated cell-to-cell attraction as the molecular mechanism for different effects on motility. By using strongly attractive mutant strains, we reveal that the survivability under ceftriaxone treatment depends on motility. Combining our results, we find that sequential treatment with azithromycin and ceftriaxone is synergistic. Taken together, we demonstrate that antibiotics modulate T4P-mediated attractions and hence cell motility and colony fluidity.
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Affiliation(s)
- Tom Cronenberg
- Institute for Biological Physics, University of Cologne, Köln, Germany
| | - Marc Hennes
- Institute for Biological Physics, University of Cologne, Köln, Germany
| | - Isabelle Wielert
- Institute for Biological Physics, University of Cologne, Köln, Germany
| | - Berenike Maier
- Institute for Biological Physics, University of Cologne, Köln, Germany
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24
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Abstract
Persister cells are defined as a small fraction of phenotypic variants in a cell population that are temporarily tolerant to bactericidal antibiotics. Persisters are not mutant cells; they generally survive lethal concentrations of antibiotics due to their transient nongrowing state. Persister cells have the ability to resuscitate after the end of antibiotic treatment. Despite significant advancements in the understanding of the molecular mechanisms underlying persister formation, we still have little information about their resuscitation mechanisms. In this chapter, we describe a method to detect and monitor persister resuscitation at the single-cell level using flow cytometry analysis. This method enables us to not only assess the resuscitation characteristics of persisters but also determine and quantify various subpopulations in antibiotic-treated cultures, including viable but nonculturable (VBNC) and dead cells.
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Affiliation(s)
- Sayed Golam Mohiuddin
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, USA
| | - Mehmet A Orman
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, USA.
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25
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Rocha-Granados MC, Zenick B, Englander HE, Mok WWK. The social network: Impact of host and microbial interactions on bacterial antibiotic tolerance and persistence. Cell Signal 2020; 75:109750. [PMID: 32846197 DOI: 10.1016/j.cellsig.2020.109750] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/07/2020] [Accepted: 08/20/2020] [Indexed: 12/13/2022]
Abstract
Antibiotics have vastly improved our quality of life since their discovery and introduction into modern medicine. Yet, widespread use and misuse have compromised the efficacy of these compounds and put our ability to cure infectious diseases in jeopardy. To defend themselves against antibiotics, bacteria have evolved an arsenal of survival strategies. In addition to acquiring mutations and genetic determinants that confer antibiotic resistance, bacteria can respond to environmental cues and adopt reversible phenotypic changes that transiently enhance their ability to survive adverse conditions, including those brought on by antibiotics. These antibiotic tolerant and persistent bacteria, which are prevalent in biofilms and can survive antimicrobial therapy without inheriting resistance, are thought to underlie treatment failure and infection relapse. At infection sites, bacteria encounter a range of signals originating from host immunity and the local microbiota that can induce transcriptomic and metabolic reprogramming. In this review, we will focus on the impact of host factors and microbial interactions on antibiotic tolerance and persistence. We will also outline current efforts in leveraging the knowledge of host-microbe and microbe-microbe interactions in designing therapies that potentiate antibiotic activity and reduce the burden caused by recurrent infections.
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Affiliation(s)
| | - Blesing Zenick
- Department of Molecular Biology & Biophysics, UCONN Health, Farmington, CT, 06032, USA
| | - Hanna E Englander
- Department of Molecular Biology & Biophysics, UCONN Health, Farmington, CT, 06032, USA; Department of Physiology & Neurobiology, University of Connecticut, Storrs, CT 06269-3156, United States of America
| | - Wendy W K Mok
- Department of Molecular Biology & Biophysics, UCONN Health, Farmington, CT, 06032, USA.
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26
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Proteomic Study of the Survival and Resuscitation Mechanisms of Filamentous Persisters in an Evolved Escherichia coli Population from Cyclic Ampicillin Treatment. mSystems 2020; 5:5/4/e00462-20. [PMID: 32723793 PMCID: PMC7394356 DOI: 10.1128/msystems.00462-20] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Through adaptive laboratory evolution (ALE) experiments, it was recently found that when a bacterial population was repetitively treated with antibiotics, they will adapt to the treatment conditions and become tolerant to the drug. In this study, we utilized an ampicillin-tolerant Escherichia coli population isolated from an ALE experiment to study the mechanisms of persistence during ampicillin treatment and resuscitation. Interestingly, the persisters of this population exhibit filamentous morphology upon ampicillin treatment, and the filaments are getting longer over time. Proteomics analysis showed that proteins involved in carbohydrate metabolism are upregulated during antibiotic treatment, in addition to those involved in the oxidative stress response. Bacterial SOS response, which is associated with filamentation, was found to be induced on account of the increasing expression of RecA. Measurement of endogenous reactive oxygen species (ROS) revealed that the population have ∼100-fold less ROS generation under ampicillin treatment than the wild type, leading to a lower mutagenesis rate. Single-cell observations through time-lapse microscopy show that resuscitation of the filaments is stochastic. During resuscitation, proteins involved in the tricarboxylic acid (TCA) cycle, glyoxylate cycle and glycolytic processes, and ATP generation are downregulated, while ribosomal proteins and porins are upregulated in the filaments. One particular protein, ElaB, was upregulated by over 7-fold in the filaments after 3 h of resuspension in fresh medium, but its expression went down after the filaments divided. Knockout of elaB increased persistence on wild-type E. coli, and upon resumption of growth, mutants lacking elaB have a higher fraction of small colony variants (SCVs) than the wild type.IMPORTANCE Persisters are a subpopulation of cells with enhanced survival toward antibiotic treatment and have the ability to resume normal growth when the antibiotic stress is lifted. Although proteomics is the most suitable tool to study them from a system-level perspective, the number of persisters that present naturally is too few for proteomics analysis, and thus the complex mechanisms through which they are able to survive antibiotic stresses and resuscitate in fresh medium remain poorly understood. To overcome that challenge, we studied an evolved Escherichia coli population with elevated persister fraction under ampicillin treatment and obtained its proteome profiles during antibiotic treatment and resuscitation. We discovered that during treatment with ampicillin, this tolerant population employs an active oxidative stress response and exhibits lower ROS levels than the wild type. Moreover, an inner membrane protein which has implications in various stress responses, ElaB, was found to be highly upregulated in the persisters during resuscitation, and its knockout caused increased formation of small colony variants after ampicillin treatment, suggesting that ElaB is important for persisters to resume normal growth.
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27
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Mohiuddin SG, Kavousi P, Orman MA. Flow-cytometry analysis reveals persister resuscitation characteristics. BMC Microbiol 2020; 20:202. [PMID: 32640993 PMCID: PMC7346475 DOI: 10.1186/s12866-020-01888-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/29/2020] [Indexed: 12/27/2022] Open
Abstract
Background Persisters and viable but non-culturable (VBNC) cells are two phenotypic variants known to be highly tolerant to antibiotics. Although both cell types are stained as live and often appear as nongrowing during antibiotic treatment, the only distinguishing feature is the ability of persisters to recolonize in standard culture media in the absence of antibiotics. Despite considerable progress in the characterization of persister formation mechanisms, their resuscitation mechanisms remain unclear due to technical limitations in detecting and isolating these cell types in culture environments that are highly heterogeneous. Results In this study, we used a methodology integrating flow cytometry, fluorescent protein expression systems and ampicillin-mediated cell lysing technique to monitor persister resuscitation at the single-cell level. With this method, we were able to investigate the effects of various culture conditions (e.g., antibiotic treatment time, the length of the stationary phase in overnight pre-cultures, or pretreatment of cells with a metabolic inhibitor) on persister resuscitation. Although we observed long-term pre-cultures have many more VBNC cells compared to short-term pre-cultures, only a small fraction of non-lysed cells was able to resuscitate in all conditions tested. Regardless of pre-culturing and ampicillin treatment times, these persister cells started to resuscitate within 1 hour, after they were transferred to fresh liquid media, with the same doubling time that normal cells have. Our analysis further showed that ampicillin was not able to lyse the cells in the presence of arsenate, a metabolic inhibitor commonly used to increase bacterial persistence. However, the removal of arsenate during antibiotic treatment resulted in cell lysis and a reduction in persister levels despite the significant decrease in ATP levels in the cells. Conclusions The strategy presented in this study helps us monitor persister resuscitation at the single-cell level, and simultaneously quantify persister, VBNC and dead cell subpopulations in ampicillin-treated cultures. Our results indicate that the characterization of persister resuscitation with flow cytometry will enhance the current molecular-level understanding of persistence and its evolution.
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Affiliation(s)
- Sayed Golam Mohiuddin
- Department of Chemical and Biomolecular Engineering, University of Houston, S222 Engineering Bldg 1, 4726 Calhoun Rd, Houston, TX, 77204, USA
| | - Pouria Kavousi
- Department of Chemical and Biomolecular Engineering, University of Houston, S222 Engineering Bldg 1, 4726 Calhoun Rd, Houston, TX, 77204, USA
| | - Mehmet A Orman
- Department of Chemical and Biomolecular Engineering, University of Houston, S222 Engineering Bldg 1, 4726 Calhoun Rd, Houston, TX, 77204, USA.
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Zhang D, Hu Y, Zhu Q, Huang J, Chen Y. Proteomic interrogation of antibiotic resistance and persistence in Escherichia coli - progress and potential for medical research. Expert Rev Proteomics 2020; 17:393-409. [PMID: 32567419 DOI: 10.1080/14789450.2020.1784731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Introduction Escherichia coli strains possess two survival strategies to endure lethal antibiotic exposure including antibiotic resistance and persistence, in which persistence can contribute to the emergence of antibiotic resistance and increasing the risk of multidrug resistance. Using high-throughput proteomics for the comprehensive understanding of mechanisms of antibiotic resistance and persistence is an effective strategy for development of target-based anti-bacterial therapies. Areas covered In this review, we summarize a comprehensive proteomic perspective of antibiotic resistance and persistence in E. coli, and overview of anti-antibiotic resistance and anti-persister molecules and strategies for the development of potential therapies. Expert opinion Proteomics allows us to globally identify the critical proteins and pathways involved in antibiotic resistance and persistence. Advancements in methodologies of proteomics and multi-omic strategies are required to overcome the limitations of proteomics and better understand mechanisms of antibiotic resistance and persistence in E. coli, and to open the possibility for identification of new targets for alternative strategies in therapeutics.
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Affiliation(s)
- Danfeng Zhang
- School of Biological Science and Biotechnology, Minnan Normal University , Zhangzhou, China
| | - Yuanqing Hu
- School of Biological Science and Biotechnology, Minnan Normal University , Zhangzhou, China
| | - Qiuqiang Zhu
- School of Biological Science and Biotechnology, Minnan Normal University , Zhangzhou, China
| | - Jiafu Huang
- School of Biological Science and Biotechnology, Minnan Normal University , Zhangzhou, China.,Engineering Technological Center of Mushroom Industry , Zhangzhou, China
| | - Yiyun Chen
- School of Biological Science and Biotechnology, Minnan Normal University , Zhangzhou, China
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