1
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Gao S, Zhang Z, Xu X, Zhou H, Zhu H, Zhang Y, Cao X, Zhou W, Shen H. Characteristics of a capnophilic small colony variant of Escherichia coli co-isolated with two other strains from a patient with bacteremia in China. Arch Microbiol 2022; 204:333. [PMID: 35585303 DOI: 10.1007/s00203-022-02932-8] [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: 08/26/2021] [Revised: 04/16/2022] [Accepted: 04/19/2022] [Indexed: 11/29/2022]
Abstract
Small colony variants (SCVs) are a slow-growing subpopulation of bacteria characterized by their atypical colony morphology and distinct biochemical properties, which are known to cause chronic persistent infections. Here, we investigated the characteristics of three phenotypes of Escherichia coli, including a capnophilic SCV, co-isolated from a 64-year-old patient with bacteremia in China. The three strains were identified as a capnophilic strain (EC1), a capnophilic SCV (EC2), and a normal colony strain (EC3). The EC1 and EC2 strains did not grow in the absence of CO2, while the EC2 colonies were pinpoint in appearance and had the ability to revert to the normal colony phenotype. The growth of the SCV was slow and not enhanced in the presence of thymidine, hemin, thiamine, and menadione. The results of antimicrobial susceptibility among the three strains showed similar sensitivity to cefoxitin and imipenem, but resistant to most of the other antimicrobials tested. Whole-genome sequencing showed that no genetic mutational variations associated with SCVs were observed, while EC1, EC2 and the revertible strains of EC2 lacked the can gene. Multi-locus sequence typing showed that all strains belonged to ST457 and nucleotide similarity analysis indicated that they had high homology. In conclusion, we report rarely described co-isolated forms of three phenotypes of E. coli that included a capnophilic SCV in a patient with bacteremia. The capnophilic SCV strain had atypical morphology and biochemical characteristics in the absence of can gene. Based on our findings, we have discussed the laboratory identification, characterization, mechanisms, and clinical treatment of capnophilic SCV strains.
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Affiliation(s)
- Shuo Gao
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China
| | - Zhifeng Zhang
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China
| | - Xuejing Xu
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China
| | - Hui Zhou
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China
| | - Hong Zhu
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China
| | - Yan Zhang
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China
| | - Xiaoli Cao
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China
| | - Wanqing Zhou
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China.
| | - Han Shen
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu, China.
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2
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Zhang X, Huang D, Zhao Z, Cai X, Cai W, Li G. Bis-molybdopterin guanine dinucleotide modulates hemolysin expression under anaerobiosis and contributes to fitness in vivo in uropathogenic Escherichia coli. Mol Microbiol 2021; 116:1216-1231. [PMID: 34494331 DOI: 10.1111/mmi.14809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/31/2021] [Accepted: 09/05/2021] [Indexed: 01/10/2023]
Abstract
Uropathogenic Escherichia coli (UPEC) is the primary causative agent of urinary tract infections (UTIs). Successful urinary tract colonization requires appropriate expression of virulence factors in response to host environmental cues, such as limited oxygen and iron availability. Hemolysin is a pore-forming toxin, and its expression correlates with the severity of UPEC infection. Previously, we showed that hemolysin expression is enhanced under anaerobic conditions; however, the genetic basis and regulatory mechanisms involved remain undefined. Here, a transposon-based forward screen identified bis-molybdopterin guanine dinucleotide cofactor (bis-MGD) biosynthesis as an important factor for a full transcription of hemolysin under anaerobiosis but not under aerobiosis. bis-MGD positively influences hemolysin transcription via c3566-c3568, an operon immediately upstream of and cotranscribed with hlyCABD. Furthermore, suppressor mutation analysis identified the nitrogen regulator NtrC as a direct repressor of c3566-c3568-hlyCABD expression, and intact bis-MGD biosynthesis downregulated ntrC expression, thus at least partially explaining the positive role of bis-MGD in modulating hemolysin expression. Finally, bis-MGD is involved in hemolysin-mediated uroepithelial cell death and contributes to the competitive fitness of UPEC in a murine model of UTI. Collectively, our data establish that bis-MGD biosynthesis plays a crucial role in UPEC fitness in vivo, thus providing a potential target for combatting UTIs.
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Affiliation(s)
- Xinyang Zhang
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Dongyan Huang
- Jiangxi Engineering Research Center for Animal Health Products, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China.,Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Zihui Zhao
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Xuwang Cai
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Wentong Cai
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Ganwu Li
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.,Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
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3
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Greninger AL, Addetia A, Tao Y, Adler A, Qin X. Inactivation of genes in oxidative respiration and iron acquisition pathways in pediatric clinical isolates of Small colony variant Enterobacteriaceae. Sci Rep 2021; 11:7457. [PMID: 33811225 PMCID: PMC8018945 DOI: 10.1038/s41598-021-86764-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 03/11/2021] [Indexed: 02/01/2023] Open
Abstract
Isolation of bacterial small colony variants (SCVs) from clinical specimens is not uncommon and can fundamentally change the outcome of the associated infections. Bacterial SCVs often emerge with their normal colony phenotype (NCV) co-isolates in the same sample. The basis of SCV emergence in vivo is not well understood in Gram-negative bacteria. In this study, we interrogated the causal genetic lesions of SCV growth in three pairs of NCV and SCV co-isolates of Escherichia coli, Citrobacter freundii, and Enterobacter hormaechei. We confirmed SCV emergence was attributed to limited genomic mutations: 4 single nucleotide variants in the E. coli SCV, 5 in C. freundii, and 8 in E. hormaechei. In addition, a 10.2 kb chromosomal segment containing 11 genes was deleted in the E. hormaechei SCV isolate. Each SCV had at least one coding change in a gene associated with bacterial oxidative respiration and another involved in iron capture. Chemical and genetic rescue confirmed defects in heme biosynthesis for E. coli and C. freundii and lipoic acid biosynthesis in E. hormaachei were responsible for the SCV phenotype. Prototrophic growth in all 3 SCV Enterobacteriaceae species was unaffected under anaerobic culture conditions in vitro, illustrating how SCVs may persist in vivo.
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Affiliation(s)
- Alexander L. Greninger
- grid.34477.330000000122986657Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA USA ,grid.240741.40000 0000 9026 4165Seattle Children’s Hospital, Seattle, WA USA
| | - Amin Addetia
- grid.34477.330000000122986657Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA USA ,grid.240741.40000 0000 9026 4165Seattle Children’s Hospital, Seattle, WA USA
| | - Yue Tao
- grid.16821.3c0000 0004 0368 8293Shanghai Children’s Medical Center, Translational Research Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127 China
| | - Amanda Adler
- grid.240741.40000 0000 9026 4165Seattle Children’s Hospital, Seattle, WA USA
| | - Xuan Qin
- grid.34477.330000000122986657Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA USA ,grid.240741.40000 0000 9026 4165Seattle Children’s Hospital, Seattle, WA USA
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4
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Reiskind MOB, Moody ML, Bolnick DI, Hanifin CT, Farrior CE. Nothing in Evolution Makes Sense Except in the Light of Biology. Bioscience 2021; 71:370-382. [PMID: 33867868 PMCID: PMC8038875 DOI: 10.1093/biosci/biaa170] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A key question in biology is the predictability of the evolutionary process. If we can correctly predict the outcome of evolution, we may be better equipped to anticipate and manage species' adaptation to climate change, habitat loss, invasive species, or emerging infectious diseases, as well as improve our basic understanding of the history of life on Earth. In the present article, we ask the questions when, why, and if the outcome of future evolution is predictable. We first define predictable and then discuss two conflicting views: that evolution is inherently unpredictable and that evolution is predictable given the ability to collect the right data. We identify factors that generate unpredictability, the data that might be required to make predictions at some level of precision or at a specific timescale, and the intellectual and translational value of understanding when prediction is or is not possible.
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Affiliation(s)
- Martha O Burford Reiskind
- Department of Biological Sciences and the director of the Genetic and Genomic Scholars graduate program, North Carolina State University, Raleigh, North Carolina, United States
| | - Michael L Moody
- Department of Biological Sciences and director of Herbarium UTEP, University of Texas, El Paso, El Paso, Texas, United States
| | - Daniel I Bolnick
- University of Connecticut, Mansfield, Connecticut, United States, and editor-in-chief of The American Naturalist, Chicago, Illinois, United States
| | | | - Caroline E Farrior
- University of Texas at Austin, Austin, Texas, United States, The author order was determined by a random number generator
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5
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Desjardins E, Kurtz J, Kranke N, Lindeza A, Richter SH. Beyond Standardization: Improving External Validity and Reproducibility in Experimental Evolution. Bioscience 2021. [DOI: 10.1093/biosci/biab008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Discussions of reproducibility are casting doubts on the credibility of experimental outcomes in the life sciences. Although experimental evolution is not typically included in these discussions, this field is also subject to low reproducibility, partly because of the inherent contingencies affecting the evolutionary process. A received view in experimental studies more generally is that standardization (i.e., rigorous homogenization of experimental conditions) is a solution to some issues of significance and internal validity. However, this solution hides several difficulties, including a reduction of external validity and reproducibility. After explaining the meaning of these two notions in the context of experimental evolution, we import from the fields of animal research and ecology and suggests that systematic heterogenization of experimental factors could prove a promising alternative. We also incorporate into our analysis some philosophical reflections on the nature and diversity of research objectives in experimental evolution.
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Affiliation(s)
- Eric Desjardins
- Rotman Institute of Philosophy, Department of Philosophy, University of Western Ontario, London, Ontario, Canada
| | | | | | | | - S Helene Richter
- RG Behavioural Biology and Animal Welfare, Institute of Neuro and Behavioural Biology all at the WWU, Münster, Germany
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6
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Hubbard ATM, Bulgasim I, Roberts AP. A novel hemA mutation is responsible for a small-colony-variant phenotype in Escherichia coli. MICROBIOLOGY-SGM 2020; 167. [PMID: 32762803 DOI: 10.1099/mic.0.000962] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We identified a small colony variant (SCV) of an amoxicillin/clavulanic acid-resistant derivative of a clinical isolate of Escherichia coli from Malawi, which was selected for in vitro in a subinhibitory concentration of gentamicin. The SCV was auxotrophic for hemin and had impaired biofilm formation compared to the ancestral isolates. A single novel nucleotide polymorphism (SNP) in hemA, which encodes a glutamyl-tRNA reductase that catalyses the initial step of porphyrin biosynthesis leading to the production of haem, was responsible for the SCV phenotype. We showed the SNP in hemA resulted in a significant fitness cost to the isolate, which persisted even in the presence of hemin. However, the phenotype quickly reverted during sequential sub-culturing in liquid growth media. As hemA is not found in mammalian cells, and disruption of the gene results in a significant fitness cost, it represents a potential target for novel drug development specifically for the treatment of catheter-associated urinary tract infections caused by E. coli.
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Affiliation(s)
- Alasdair T M Hubbard
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Issra Bulgasim
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Adam P Roberts
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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7
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Wang L, Zhu Z, Qian H, Li Y, Chen Y, Ma P, Gu B. Comparative genome analysis of 15 clinical Shigella flexneri strains regarding virulence and antibiotic resistance. AIMS Microbiol 2019; 5:205-222. [PMID: 31663057 PMCID: PMC6787350 DOI: 10.3934/microbiol.2019.3.205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/07/2019] [Indexed: 12/30/2022] Open
Abstract
Shigellosis is the major cause of dysentery globally. It is mainly attributed to two Shigella species, Shigella sonnei and Shigella flexneri, which leads to approximately 165 million infections and 1.1 million deaths each year. Rapid increase and widening of spectrum in antibiotics resistance make Shigella hard to be adequately controlled through existing prevention and treatment measures. It has also been observed that enhanced virulence and advent of antibiotic resistance (AR) could arise almost simultaneously. However, genetic linkages between the two factors are missing or largely ignored, which hinders experimental verification of the relationship. In this study, we sequenced 15 clinically isolated S. flexneri strains. Genome assembly, annotation and comparison were performed through routine pipelines. Differential resistant profiles of all 15 S. flexneri strains to nine antibiotics were experimentally verified. Virulence factors (VFs) belonging to 4 categories and 31 functional groups from the Virulence Factor Database (VFDB) were used to screen all Shigella translated CDSs. Distribution patterns of virulence factors were analysed by correlating with the profiles of bacterial antibiotics resistance. In addition, multi-resistant S. flexneri strains were compared with antibiotic-sensitive strains by focusing on the abundance or scarcity of specific groups of VFs. By doing these, a clear view of the relationships between virulence factors and antibiotics resistance in Shigella could be achieved, which not only provides a set of genetic evidence to support the interactions between VFs and AR but could also be used as a guidance for further verification of the relationships through manipulating specific groups of virulence factors.
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Affiliation(s)
- Liang Wang
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou 221000, Jiangsu China.,Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou 221000, Jiangsu China
| | - Zuobin Zhu
- Department of Genetics, School of Life Sciences, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Huimin Qian
- Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China
| | - Ying Li
- Medical Technology School of Xuzhou Medical University, Xuzhou 221004, China
| | - Ying Chen
- Medical Technology School of Xuzhou Medical University, Xuzhou 221004, China
| | - Ping Ma
- Medical Technology School of Xuzhou Medical University, Xuzhou 221004, China.,Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221006, China
| | - Bing Gu
- Medical Technology School of Xuzhou Medical University, Xuzhou 221004, China.,Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221006, China
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8
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Marcelino VR, Wille M, Hurt AC, González-Acuña D, Klaassen M, Schlub TE, Eden JS, Shi M, Iredell JR, Sorrell TC, Holmes EC. Meta-transcriptomics reveals a diverse antibiotic resistance gene pool in avian microbiomes. BMC Biol 2019; 17:31. [PMID: 30961590 PMCID: PMC6454771 DOI: 10.1186/s12915-019-0649-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/20/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Antibiotic resistance is rendering common bacterial infections untreatable. Wildlife can incorporate and disperse antibiotic-resistant bacteria in the environment, such as water systems, which in turn serve as reservoirs of resistance genes for human pathogens. Anthropogenic activity may contribute to the spread of bacterial resistance cycling through natural environments, including through the release of human waste, as sewage treatment only partially removes antibiotic-resistant bacteria. However, empirical data supporting these effects are currently limited. Here we used bulk RNA-sequencing (meta-transcriptomics) to assess the diversity and expression levels of functionally viable resistance genes in the gut microbiome of birds with aquatic habits in diverse locations. RESULTS We found antibiotic resistance genes in birds from all localities, from penguins in Antarctica to ducks in a wastewater treatment plant in Australia. Comparative analysis revealed that birds feeding at the wastewater treatment plant carried the greatest resistance gene burden, including genes typically associated with multidrug resistance plasmids as the aac(6)-Ib-cr gene. Differences in resistance gene burden also reflected aspects of bird ecology, taxonomy, and microbial function. Notably, ducks, which feed by dabbling, carried a higher abundance and diversity of resistance genes than turnstones, avocets, and penguins, which usually prey on more pristine waters. CONCLUSIONS These transcriptome data suggest that human waste, even if it undergoes treatment, might contribute to the spread of antibiotic resistance genes to the wild. Differences in microbiome functioning across different bird lineages may also play a role in the antibiotic resistance burden carried by wild birds. In summary, we reveal the complex factors explaining the distribution of resistance genes and their exchange routes between humans and wildlife, and show that meta-transcriptomics is a valuable tool to access functional resistance genes in whole microbial communities.
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Affiliation(s)
- Vanessa R Marcelino
- Marie Bashir Institute for Infectious Diseases and Biosecurity and Sydney Medical School, The University of Sydney, Sydney, NSW, 2006, Australia. .,Westmead Institute for Medical Research, Westmead, NSW, 2145, Australia. .,School of Life & Environmental Sciences, Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Michelle Wille
- WHO Collaborating Centre for Reference and Research on Influenza, at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, 3000, Australia
| | - Aeron C Hurt
- WHO Collaborating Centre for Reference and Research on Influenza, at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, 3000, Australia
| | - Daniel González-Acuña
- Laboratorio de Parásitos y Enfermedades de Fauna Silvestre, Facultad de Ciencias Veterinarias, Universidad de Concepción, 3349001, Concepción, Chile
| | - Marcel Klaassen
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC, 3216, Australia
| | - Timothy E Schlub
- Faculty of Medicine and Health, Sydney School of Public Health, The University of Sydney, Sydney, NSW, 2006, Australia
| | - John-Sebastian Eden
- Marie Bashir Institute for Infectious Diseases and Biosecurity and Sydney Medical School, The University of Sydney, Sydney, NSW, 2006, Australia.,Westmead Institute for Medical Research, Westmead, NSW, 2145, Australia.,School of Life & Environmental Sciences, Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Mang Shi
- Marie Bashir Institute for Infectious Diseases and Biosecurity and Sydney Medical School, The University of Sydney, Sydney, NSW, 2006, Australia.,School of Life & Environmental Sciences, Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Jonathan R Iredell
- Marie Bashir Institute for Infectious Diseases and Biosecurity and Sydney Medical School, The University of Sydney, Sydney, NSW, 2006, Australia.,Westmead Institute for Medical Research, Westmead, NSW, 2145, Australia
| | - Tania C Sorrell
- Marie Bashir Institute for Infectious Diseases and Biosecurity and Sydney Medical School, The University of Sydney, Sydney, NSW, 2006, Australia.,Westmead Institute for Medical Research, Westmead, NSW, 2145, Australia
| | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity and Sydney Medical School, The University of Sydney, Sydney, NSW, 2006, Australia.,School of Life & Environmental Sciences, Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
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9
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The high prevalence of antibiotic heteroresistance in pathogenic bacteria is mainly caused by gene amplification. Nat Microbiol 2019; 4:504-514. [PMID: 30742072 DOI: 10.1038/s41564-018-0342-0] [Citation(s) in RCA: 204] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 12/06/2018] [Indexed: 12/22/2022]
Abstract
When choosing antibiotics to treat bacterial infections, it is assumed that the susceptibility of the target bacteria to an antibiotic is reflected by laboratory estimates of the minimum inhibitory concentration (MIC) needed to prevent bacterial growth. A caveat of using MIC data for this purpose is heteroresistance, the presence of a resistant subpopulation in a main population of susceptible cells. We investigated the prevalence and mechanisms of heteroresistance in 41 clinical isolates of the pathogens Escherichia coli, Salmonella enterica, Klebsiella pneumoniae and Acinetobacter baumannii against 28 different antibiotics. For the 766 bacteria-antibiotic combinations tested, as much as 27.4% of the total was heteroresistant. Genetic analysis demonstrated that a majority of heteroresistance cases were unstable, with an increased resistance of the subpopulations resulting from spontaneous tandem amplifications, typically including known resistance genes. Using mathematical modelling, we show how heteroresistance in the parameter range estimated in this study can result in the failure of antibiotic treatment of infections with bacteria that are classified as antibiotic susceptible. The high prevalence of heteroresistance with the potential for treatment failure highlights the limitations of MIC as the sole criterion for susceptibility determinations. These results call for the development of facile and rapid protocols to identify heteroresistance in pathogens.
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10
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Abstract
The composite members of the microbiota face a range of selective pressures and must adapt to persist in the host. We highlight recent work characterizing the evolution and transfer of genetic information across nested scales of host-associated microbiota, which enable resilience to biotic and abiotic perturbations. At the strain level, we consider the preservation and diversification of adaptive information in progeny lineages. At the community level, we consider genetic exchange between distinct microbes in the ecosystem. Finally, we frame microbiomes as open systems subject to acquisition of novel information from foreign ecosystems through invasion by outsider microbes.
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11
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Adaptation Through Lifestyle Switching Sculpts the Fitness Landscape of Evolving Populations: Implications for the Selection of Drug-Resistant Bacteria at Low Drug Pressures. Genetics 2019; 211:1029-1044. [PMID: 30670539 DOI: 10.1534/genetics.119.301834] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/16/2019] [Indexed: 12/21/2022] Open
Abstract
Novel genotypes evolve under selection through mutations in pre-existing genes. However, mutations have pleiotropic phenotypic effects that influence the fitness of emerging genotypes in complex ways. The evolution of antimicrobial resistance is mediated by selection of mutations in genes coding for antibiotic-target proteins. Drug-resistance is commonly associated with a fitness cost due to the impact of resistance-conferring mutations on protein function and/or stability. These costs are expected to prohibit the selection of drug-resistant mutations at low drug pressures. Using laboratory evolution of rifampicin resistance in Escherichia coli, we show that when exposed intermittently to low concentration (0.1 × minimal inhibitory concentration) of rifampicin, the evolution of canonical drug resistance was indeed unfavorable. Instead, these bacterial populations adapted by evolving into small-colony variants that displayed enhanced pellicle-forming ability. This shift in lifestyle from planktonic to pellicle-like was necessary for enhanced fitness at low drug pressures, and was mediated by the genetic activation of the fim operon promoter, which allowed expression of type I fimbriae. Upon continued low drug exposure, these bacteria evolved exclusively into high-level drug-resistant strains through mutations at a limited set of loci within the rifampicin-resistance determining region of the rpoB gene. We show that our results are explained by mutation-specific epistasis, resulting in differential impact of lifestyle switching on the competitive fitness of different rpoB mutations. Thus, lifestyle-alterations that are selected at low selection pressures have the potential to modify the fitness effects of mutations, change the genetic structure, and affect the ultimate fate of evolving populations.
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12
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Shaw RG. From the Past to the Future: Considering the Value and Limits of Evolutionary Prediction. Am Nat 2019; 193:1-10. [DOI: 10.1086/700565] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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13
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Bolnick DI, Barrett RD, Oke KB, Rennison DJ, Stuart YE. (Non)Parallel Evolution. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2018. [DOI: 10.1146/annurev-ecolsys-110617-062240] [Citation(s) in RCA: 155] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Parallel evolution across replicate populations has provided evolutionary biologists with iconic examples of adaptation. When multiple populations colonize seemingly similar habitats, they may evolve similar genes, traits, or functions. Yet, replicated evolution in nature or in the laboratory often yields inconsistent outcomes: Some replicate populations evolve along highly similar trajectories, whereas other replicate populations evolve to different extents or in distinct directions. To understand these heterogeneous outcomes, biologists are increasingly treating parallel evolution not as a binary phenomenon but rather as a quantitative continuum ranging from parallel to nonparallel. By measuring replicate populations’ positions along this (non)parallel continuum, we can test hypotheses about evolutionary and ecological factors that influence the extent of repeatable evolution. We review evidence regarding the manifestation of (non)parallel evolution in the laboratory, in natural populations, and in applied contexts such as cancer. We enumerate the many genetic, ecological, and evolutionary processes that contribute to variation in the extent of parallel evolution.
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Affiliation(s)
- Daniel I. Bolnick
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
- Current affiliation: Department of Ecology and Evolution, University of Connecticut, Storrs, Connecticut 06268, USA
| | | | - Krista B. Oke
- Redpath Museum, McGill University, Montreal, Quebec H3A 2K6, Canada
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California 95060, USA
| | - Diana J. Rennison
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Yoel E. Stuart
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
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14
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Xia H, Tang Q, Song J, Ye J, Wu H, Zhang H. A yigP mutant strain is a small colony variant of E. coli and shows pleiotropic antibiotic resistance. Can J Microbiol 2017; 63:961-969. [PMID: 28915357 DOI: 10.1139/cjm-2017-0347] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Small colony variants (SCVs) are a commonly observed subpopulation of bacteria that have a small colony size and distinctive biochemical characteristics. SCVs are more resistant than the wild type to some antibiotics and usually cause persistent infections in the clinic. SCV studies have been very active during the past 2 decades, especially Staphylococcus aureus SCVs. However, fewer studies on Escherichia coli SCVs exist, so we studied an E. coli SCV during an experiment involving the deletion of the yigP locus. PCR and DNA sequencing revealed that the SCV was attributable to a defect in the yigP function. Furthermore, we investigated the antibiotic resistance profile of the E. coli SCV and it showed increased erythromycin, kanamycin, and d-cycloserine resistance, but collateral sensitivity to ampicillin, polymyxin, chloramphenicol, tetracycline, rifampin, and nalidixic acid. We tried to determine the association between yigP and the pleiotropic antibiotic resistance of the SCV by analyzing biofilm formation, cellular morphology, and coenzyme Q (Q8) production. Our results indicated that impaired Q8 biosynthesis was the primary factor that contributed to the increased resistance and collateral sensitivity of the SCV. This study offers a novel genetic basis for E. coli SCVs and an insight into the development of alternative antimicrobial strategies for clinical therapy.
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Affiliation(s)
- Hui Xia
- a State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Qiongwei Tang
- a State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Jie Song
- a State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Jiang Ye
- a State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Haizhen Wu
- a State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China.,b Department of Applied Biology, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Huizhan Zhang
- a State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China.,b Department of Applied Biology, East China University of Science and Technology, Shanghai, People's Republic of China
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