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Geoffroy F, Uecker H. Limits to evolutionary rescue by conjugative plasmids. Theor Popul Biol 2023; 154:102-117. [PMID: 37923145 DOI: 10.1016/j.tpb.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 10/06/2023] [Accepted: 10/16/2023] [Indexed: 11/07/2023]
Abstract
Plasmids may carry genes coding for beneficial traits and thus contribute to adaptation of bacterial populations to environmental stress. Conjugative plasmids can horizontally transfer between cells, which a priori facilitates the spread of adaptive alleles. However, if the potential recipient cell is already colonized by another incompatible plasmid, successful transfer may be prevented. Competition between plasmids can thus limit horizontal transfer. Previous modeling has indeed shown that evolutionary rescue by a conjugative plasmid is hampered by incompatible resident plasmids in the population. If the rescue plasmid is a mutant variant of the resident plasmid, both plasmids transfer at the same rates. A high conjugation rate then has two, potentially opposing, effects - a direct positive effect on spread of the rescue plasmid and an increase in the fraction of resident plasmid cells. This raises the question whether a high conjugation rate always benefits evolutionary rescue. In this article, we systematically analyze three models of increasing complexity to disentangle the benefits and limits of increasing horizontal gene transfer in the presence of plasmid competition and plasmid costs. We find that the net effect can be positive or negative and that the optimal transfer rate is thus not always the highest one. These results can contribute to our understanding of the many facets of plasmid-driven adaptation and the wide range of transfer rates observed in nature.
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Affiliation(s)
- Félix Geoffroy
- Research group Stochastic Evolutionary Dynamics, Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, Germany.
| | - Hildegard Uecker
- Research group Stochastic Evolutionary Dynamics, Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, Germany
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2
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Allain M, Mahérault AC, Gachet B, Martinez C, Condamine B, Magnan M, Kempf I, Denamur E, Landraud L. Dissemination of IncI plasmid encoding bla CTX-M-1 is not hampered by its fitness cost in the pig's gut. Antimicrob Agents Chemother 2023; 67:e0011123. [PMID: 37702541 PMCID: PMC10583664 DOI: 10.1128/aac.00111-23] [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: 02/02/2023] [Accepted: 07/01/2023] [Indexed: 09/14/2023] Open
Abstract
Multiresistance plasmids belonging to the IncI incompatibility group have become one of the most pervasive plasmid types in extended-spectrum beta-lactamase-producing Escherichia coli of animal origin. The extent of the burden imposed on the bacterial cell by these plasmids seems to modulate the emergence of "epidemic" plasmids. However, in vivo data in the natural environment of the strains are scarce. Here, we investigated the cost of a bla CTX-M-1-IncI1 epidemic plasmid in a commensal E. coli animal strain, UB12-RC, before and after oral inoculation of 15 6- to 8-week- old specific-pathogen-free pigs. Growth rate in rich medium was determined on (i) UB12-RC and derivatives, with or without plasmid, in vivo and/or in vitro evolved, and (ii) strains that acquired the plasmid in the gut during the experiment. Although bla CTX-M-1-IncI1 plasmid imposed no measurable burden on the recipient strain after conjugation and during the longitudinal carriage in the pig's gut, we observed a significant difference in the bacterial growth rate between IncI1 plasmid-carrying and plasmid-free isolates collected during in vivo carriage. Only a few mutations on the chromosome of the UB12-RC derivatives were detected by whole-genome sequencing. RNA-Seq analysis of a selected set of these strains showed that transcriptional responses to the bla CTX-M-1-IncI1 acquisition were limited, affecting metabolism, stress response, and motility functions. Our data suggest that the effect of IncI plasmid on host cells is limited, fitness cost being insufficient to act as a barrier to IncI plasmid spread among natural population of E. coli in the gut niche.
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Affiliation(s)
- Margaux Allain
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
- AP-HP, Laboratoire de Microbiologie Hygiène, Hôpital Louis Mourier, Colombes, France
| | - Anne Claire Mahérault
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
- AP-HP, Laboratoire de Microbiologie Hygiène, Hôpital Louis Mourier, Colombes, France
| | - Benoit Gachet
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
| | - Caroline Martinez
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
| | - Bénédicte Condamine
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
| | - Mélanie Magnan
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
| | - Isabelle Kempf
- ANSES, Laboratoire de Ploufragan-Plouzané-Niort, Ploufragan, France
| | - Erick Denamur
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
- AP-HP, Laboratoire de Génétique Moléculaire, Hôpital Bichat, Paris, France
| | - Luce Landraud
- Université Paris Cité and Université Sorbonne Paris Nord, INSERM, IAME, Paris, France
- AP-HP, Laboratoire de Microbiologie Hygiène, Hôpital Louis Mourier, Colombes, France
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3
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Dewan I, Uecker H. A mathematician's guide to plasmids: an introduction to plasmid biology for modellers. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001362. [PMID: 37505810 PMCID: PMC10433428 DOI: 10.1099/mic.0.001362] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 07/03/2023] [Indexed: 07/29/2023]
Abstract
Plasmids, extrachromosomal DNA molecules commonly found in bacterial and archaeal cells, play an important role in bacterial genetics and evolution. Our understanding of plasmid biology has been furthered greatly by the development of mathematical models, and there are many questions about plasmids that models would be useful in answering. In this review, we present an introductory, yet comprehensive, overview of the biology of plasmids suitable for modellers unfamiliar with plasmids who want to get up to speed and to begin working on plasmid-related models. In addition to reviewing the diversity of plasmids and the genes they carry, their key physiological functions, and interactions between plasmid and host, we also highlight selected plasmid topics that may be of particular interest to modellers and areas where there is a particular need for theoretical development. The world of plasmids holds a great variety of subjects that will interest mathematical biologists, and introducing new modellers to the subject will help to expand the existing body of plasmid theory.
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Affiliation(s)
- Ian Dewan
- Research Group Stochastic Evolutionary Dynamics, Department of Theoretical Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Hildegard Uecker
- Research Group Stochastic Evolutionary Dynamics, Department of Theoretical Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
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4
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Sipahi N, Kaya E, Çelik C, Pınar O. The Characterization and Beta-Lactam Resistance of Staphylococcal Community Recovered from Raw Bovine Milk. Antibiotics (Basel) 2023; 12:antibiotics12030556. [PMID: 36978423 PMCID: PMC10044537 DOI: 10.3390/antibiotics12030556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 03/06/2023] [Accepted: 03/08/2023] [Indexed: 03/14/2023] Open
Abstract
Staphylococci is an opportunistic bacterial population that is permanent in the normal flora of milk and poses a serious threat to animal and human health with some virulence factors and antibiotic-resistance genes. This study was aimed at identifying staphylococcal species isolated from raw milk and to determine hemolysis, biofilm, coagulase activities, and beta-lactam resistance. The raw milk samples were collected from the Düzce (Türkiye) region, and the study data represent a first for this region. The characterization of the bacteria was performed with MALDI-TOF MS and 16S rRNA sequence analysis. The presence of coa, icaB, blaZ, and mecA was investigated with PCR. A nitrocefin chromogenic assay was used for beta-lactamase screening. In this context, 84 staphylococci were isolated from 10 different species, and the dominant species was determined as S. aureus (32.14%). Although 32.14% of all staphylococci were positive for beta hemolysis, the icaB gene was found in 57.14%, coa in 46.42%, mecA in 15.47%, and blaZ in 8.33%. As a result, Staphylococcus spp. strains that were isolated from raw milk in this study contained some virulence factors at a high level, but also contained a relatively low level of beta-lactam resistance genes. However, considering the animal–environment–human interaction, it is considered that the current situation must be monitored constantly in terms of resistance concerns. It must not be forgotten that the development of resistance is in constant change among bacteria.
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Affiliation(s)
- Nisa Sipahi
- Traditional and Complementary Medicine Applied and Research Center, Düzce University, 81620 Düzce, Türkiye
- Correspondence:
| | - Ertugrul Kaya
- Medical Pharmacology Department, Medicine Faculty, Düzce University, 81620 Düzce, Türkiye;
| | - Cansu Çelik
- Food Technology Program, Food Processing Department, Vocational School of Veterinary Medicine, Istanbul University-Cerrahpasa, 34320 Istanbul, Türkiye;
| | - Orhan Pınar
- Equine and Equine Training Program, Vocational School of Veterinary Medicine, Istanbul University-Cerrahpasa, 34320 Istanbul, Türkiye;
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Gruel G, Couvin D, Guyomard-Rabenirina S, Arlet G, Bambou JC, Pot M, Roy X, Talarmin A, Tressieres B, Ferdinand S, Breurec S. High Prevalence of bla CTXM-1/IncI1-Iγ/ST3 Plasmids in Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates Collected From Domestic Animals in Guadeloupe (French West Indies). Front Microbiol 2022; 13:882422. [PMID: 35651489 PMCID: PMC9149308 DOI: 10.3389/fmicb.2022.882422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) have been classified in the group of resistant bacteria of highest priority. We determined the prevalence of ESBL-E collected in feces from household and shelter pets in Guadeloupe (French West Indies). A single rectal swab was taken from 125 dogs and 60 cats between June and September 2019. The prevalence of fecal carriage of ESBL-E was 7.6% (14/185, 95% CI: 4.2-12.4), within the range observed worldwide. The only risk factor associated with a higher prevalence of ESBL-E rectal carriage was a stay in a shelter, suggesting that refuges could be hotspots for their acquisition. All but one (Klebsiella pneumoniae from a cat) were Escherichia coli. We noted the presence of a bla CTX-M-1/IncI1-Iγ/sequence type (ST3) plasmid in 11 ESBL-producing E. coli isolates belonging to ST328 (n = 6), ST155 (n = 4) and ST953 (n = 1). A bla CTX-M-15 gene was identified in the three remaining ESBL-E isolates. The bla CTX-M-1 and most of the antimicrobial resistance genes were present in a well-conserved large conjugative IncI1-Iγ/ST3 plasmid characterized by two accessory regions containing antibiotic resistance genes. The plasmid has been detected worldwide in E. coli isolates from humans and several animal species, such as food-producing animals, wild birds and pets, and from the environment. This study shows the potential role of pets as a reservoir of antimicrobial-resistant bacteria or genes for humans and underlines the importance of basic hygiene measures by owners of companion animals.
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Affiliation(s)
- Gaëlle Gruel
- Transmission, Reservoir and Diversity of Pathogens Unit, Pasteur Institute of Guadeloupe, Pointe-à-Pitre, France
| | - David Couvin
- Transmission, Reservoir and Diversity of Pathogens Unit, Pasteur Institute of Guadeloupe, Pointe-à-Pitre, France
| | | | | | | | - Matthieu Pot
- Transmission, Reservoir and Diversity of Pathogens Unit, Pasteur Institute of Guadeloupe, Pointe-à-Pitre, France
| | | | - Antoine Talarmin
- Transmission, Reservoir and Diversity of Pathogens Unit, Pasteur Institute of Guadeloupe, Pointe-à-Pitre, France
| | - Benoit Tressieres
- INSERM 1424, Center for Clinical Investigation, University Hospital Center of Guadeloupe, Pointe-à-Pitre, France
| | - Séverine Ferdinand
- Transmission, Reservoir and Diversity of Pathogens Unit, Pasteur Institute of Guadeloupe, Pointe-à-Pitre, France
| | - Sébastien Breurec
- Transmission, Reservoir and Diversity of Pathogens Unit, Pasteur Institute of Guadeloupe, Pointe-à-Pitre, France.,INSERM 1424, Center for Clinical Investigation, University Hospital Center of Guadeloupe, Pointe-à-Pitre, France.,Faculty of Medicine Hyacinthe Bastaraud, University of the Antilles, Pointe-à-Pitre, France
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Horizontal Gene Transfer Is the Main Driver of Antimicrobial Resistance in Broiler Chicks Infected with Salmonella enterica Serovar Heidelberg. mSystems 2021; 6:e0072921. [PMID: 34427525 PMCID: PMC8409728 DOI: 10.1128/msystems.00729-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The overuse and misuse of antibiotics in clinical settings and in food production have been linked to the increased prevalence and spread of antimicrobial resistance (AR). Consequently, public health and consumer concerns have resulted in a remarkable reduction in antibiotics used for food animal production. However, there are no data on the effectiveness of antibiotic removal in reducing AR shared through horizontal gene transfer (HGT). In this study, we used neonatal broiler chicks and Salmonella enterica serovar Heidelberg, a model food pathogen, to test if chicks raised antibiotic free harbor transferable AR. We challenged chicks with an antibiotic-susceptible S. Heidelberg strain using various routes of inoculation and determined if S. Heidelberg isolates recovered carried plasmids conferring AR. We used antimicrobial susceptibility testing and whole-genome sequencing (WGS) to show that chicks grown without antibiotics harbored an antimicrobial resistant S. Heidelberg population at 14 days after challenge and chicks challenged orally acquired AR at a higher rate than chicks inoculated via the cloaca. Using 16S rRNA gene sequencing, we found that S. Heidelberg infection perturbed the microbiota of broiler chicks, and we used metagenomics and WGS to confirm that a commensal Escherichia coli population was the main reservoir of an IncI1 plasmid acquired by S. Heidelberg. The carriage of this IncI1 plasmid posed no fitness cost to S. Heidelberg but increased its fitness when exposed to acidic pH in vitro. These results suggest that HGT of plasmids carrying AR shaped the evolution of S. Heidelberg and that antibiotic use reduction alone is insufficient to limit antibiotic resistance transfer from commensal bacteria to Salmonella enterica. IMPORTANCE The reported increase in antibiotic-resistant bacteria in humans has resulted in a major shift away from antibiotic use in food animal production. This shift has been driven by the assumption that removing antibiotics will select for antibiotic susceptible bacterial taxa, which in turn will allow the currently available antibiotic arsenal to be more effective. This change in practice has highlighted new questions that need to be answered to assess the effectiveness of antibiotic removal in reducing the spread of antibiotic resistance bacteria. This research demonstrates that antibiotic-susceptible Salmonella enterica serovar Heidelberg strains can acquire multidrug resistance from commensal bacteria present in the gut of neonatal broiler chicks, even in the absence of antibiotic selection. We demonstrate that exposure to acidic pH drove the horizontal transfer of antimicrobial resistance plasmids and suggest that simply removing antibiotics from food animal production might not be sufficient to limit the spread of antimicrobial resistance.
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Roberts MG, Burgess S, Toombs-Ruane LJ, Benschop J, Marshall JC, French NP. Combining mutation and horizontal gene transfer in a within-host model of antibiotic resistance. Math Biosci 2021; 339:108656. [PMID: 34216634 DOI: 10.1016/j.mbs.2021.108656] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 11/25/2022]
Abstract
Antibiotics are used extensively to control infections in humans and animals, usually by injection or a course of oral tablets. There are several methods by which bacteria can develop antimicrobial resistance (AMR), including mutation during DNA replication and plasmid mediated horizontal gene transfer (HGT). We present a model for the development of AMR within a single host animal. We derive criteria for a resistant mutant strain to replace the existing wild-type bacteria, and for co-existence of the wild-type and mutant. Where resistance develops through HGT via conjugation we derive criteria for the resistant strain to be excluded or co-exist with the wild-type. Our results are presented as bifurcation diagrams with thresholds determined by the relative fitness of the bacteria strains, expressed in terms of reproduction numbers. The results show that it is possible that applying and then relaxing antibiotic control may lead to the bacterial load returning to pre-control levels, but with an altered structure with regard to the variants that comprise the population. Removing antimicrobial selection pressure will not necessarily reduce AMR and, at a population level, other approaches to infection prevention and control are required, particularly when AMR is driven by both mutation and mobile genetic elements.
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Affiliation(s)
- M G Roberts
- School of Natural & Computational Sciences, Massey University, Private Bag 102 904, North Shore Mail Centre, Auckland, 0745, New Zealand; New Zealand Institute for Advanced Study, Massey University, Private Bag 102 904, North Shore Mail Centre, Auckland, 0745, New Zealand; Infectious Disease Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand.
| | - S Burgess
- Infectious Disease Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; School of Veterinary Sciences, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; mEpilab, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand
| | - L J Toombs-Ruane
- Infectious Disease Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; School of Veterinary Sciences, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; mEpilab, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand
| | - J Benschop
- Infectious Disease Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; School of Veterinary Sciences, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; mEpilab, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand
| | - J C Marshall
- Infectious Disease Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; mEpilab, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; School of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand
| | - N P French
- New Zealand Institute for Advanced Study, Massey University, Private Bag 102 904, North Shore Mail Centre, Auckland, 0745, New Zealand; Infectious Disease Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; mEpilab, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand; New Zealand Food Safety Science & Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand
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Alderliesten JB, Duxbury SJN, Zwart MP, de Visser JAGM, Stegeman A, Fischer EAJ. Effect of donor-recipient relatedness on the plasmid conjugation frequency: a meta-analysis. BMC Microbiol 2020; 20:135. [PMID: 32456625 PMCID: PMC7249681 DOI: 10.1186/s12866-020-01825-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 05/18/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Conjugation plays a major role in the transmission of plasmids encoding antibiotic resistance genes in both clinical and general settings. The conjugation efficiency is influenced by many biotic and abiotic factors, one of which is the taxonomic relatedness between donor and recipient bacteria. A comprehensive overview of the influence of donor-recipient relatedness on conjugation is still lacking, but such an overview is important to quantitatively assess the risk of plasmid transfer and the effect of interventions which limit the spread of antibiotic resistance, and to obtain parameter values for conjugation in mathematical models. Therefore, we performed a meta-analysis on reported conjugation frequencies from Escherichia coli donors to various recipient species. RESULTS Thirty-two studies reporting 313 conjugation frequencies for liquid broth matings and 270 conjugation frequencies for filter matings were included in our meta-analysis. The reported conjugation frequencies varied over 11 orders of magnitude. Decreasing taxonomic relatedness between donor and recipient bacteria, when adjusted for confounding factors, was associated with a lower conjugation frequency in liquid matings. The mean conjugation frequency for bacteria of the same order, the same class, and other classes was 10, 20, and 789 times lower than the mean conjugation frequency within the same species, respectively. This association between relatedness and conjugation frequency was not found for filter matings. The conjugation frequency was furthermore found to be influenced by temperature in both types of mating experiments, and in addition by plasmid incompatibility group in liquid matings, and by recipient origin and mating time in filter matings. CONCLUSIONS In our meta-analysis, taxonomic relatedness is limiting conjugation in liquid matings, but not in filter matings, suggesting that taxonomic relatedness is not a limiting factor for conjugation in environments where bacteria are fixed in space.
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Affiliation(s)
- Jesse B. Alderliesten
- Department of Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | | | - Mark P. Zwart
- Department of Microbial Ecology, The Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | | | - Arjan Stegeman
- Department of Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Egil A. J. Fischer
- Department of Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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Saliu EM, Zentek J, Vahjen W. In vitro conjugation kinetics of AmpC, broad spectrum and extended-spectrum beta-lactamase-producing Escherichia coli donors and various Enterobacteriaceae recipients. BMC Microbiol 2020; 20:133. [PMID: 32450799 PMCID: PMC7249311 DOI: 10.1186/s12866-020-01787-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 04/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Extended spectrum beta-lactamase (ESBL)-producing enterobacteria pose a major hazard to public health. Due to the possibility of genetic transfer, ESBL genes might spread to pathogenic enterobacterial strains. Thus, information on possible genetic transfer between enterobacteria is of high interest. It was therefore the aim of this in vitro study to screen the capacity of a wide range of Enterobacteriaceae for differences in conjugation at different time points with five ESBL-producing Escherichia coli strains. RESULTS Conjugation frequencies for five potential E. coli donor strains producing the enzymes CTX-M-1, CTX-M-15, SHV-12, TEM-1, TEM-52 and CMY-2, and six potential recipient strains commonly detected in the gastrointestinal tract of poultry (E. coli, Serratia marcescens subsp. marcescens, Enterobacter cloacae, Salmonella (S.) enterica serovar Typhimurium and Proteus mirabilis) were obtained. Different combinations of donor and recipient strains were co-incubated for between 0 and 22 h and spread on selective agar. Conjugation frequencies were calculated as transconjugants per donor. Some donor and recipient strain combinations did not perform plasmid transfer within 22 h. Hence, the recipient Proteus mirabilis did not accept plasmids from any of the given donors and the E. coli ESBL10716 donor was unable to transfer its plasmid to any recipient. Enterobacter cloacae only accepted the plasmids from the donors E. coli ESBL10708 and E. coli ESBL10716 while E. coli ESBL10708 did not transfer its plasmid to Serratia marcescens subsp. marcescens. E. coli IMT11716 on the other hand did not perform conjugation with the donor E. coli ESBL10689. The remaining mating pairs differed in conjugation frequency, ranging from 10- 5 to 10- 9 transconjugants/donor. The earliest conjugation events were detected after 4 h. However, some mating pairs turned positive only after 22 h of coincubation. CONCLUSION A suitable mating pair for future in vivo studies to combat transfer of antibiotic resistance to pathogenic bacteria in broiler chicken was determined. The results of this study also suggest that the kinetic of conjugation differs between mating pairs and is independent of species origin. This should be considered when performing conjugation experiments.
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Affiliation(s)
- Eva-Maria Saliu
- Institute of Animal Nutrition, Freie Universität Berlin, Königin-Luise-Str. 49, 14195, Berlin, Germany.
| | - Jürgen Zentek
- Institute of Animal Nutrition, Freie Universität Berlin, Königin-Luise-Str. 49, 14195, Berlin, Germany
| | - Wilfried Vahjen
- Institute of Animal Nutrition, Freie Universität Berlin, Königin-Luise-Str. 49, 14195, Berlin, Germany
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