title: Effect of growth rate and selection pressure on rates of transfer of an antibiotic resistance plasmid between E. coli strains.
abstract: Antibiotic resistance increases costs for health care and causes therapy failure. An important mechanism for spreading resistance is transfer of plasmids containing resistance genes and subsequent selection. Yet the factors that influence the rate of transfer are poorly known. Rates of plasmid transfer were measured in co-cultures in chemostats of a donor and a acceptor strain under various selective pressures. To document whether specific mutations in either plasmid or acceptor genome are associated with the plasmid transfer, whole genome sequencing was performed. The DM0133 TetR tetracycline resistance plasmid was transferred between Escherichia coli K-12 strains during co-culture at frequencies that seemed higher at increased growth rate. Modeling of the take-over of the culture by the transformed strain suggests that in reality more transfer events occurred at low growth rates. At moderate selection pressure due to an antibiotic concentration that still allowed growth, a maximum transfer frequency was determined of once per 10(11) cell divisions. In the absence of tetracycline or in the presence of high concentrations the frequency of transfer was sometimes zero, but otherwise reduced by at least a factor of 5. Whole genome sequencing showed that the plasmid was transferred without mutations, but two functional mutations in the genome of the recipient strain accompanied this transfer. Exposure to concentrations of antibiotics that fall within the mutant selection window stimulated transfer of the resistance plasmid most.
authors: Department of Molecular Biology & Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors: Jasper M
authors: JM
authors: Schuurmans
authors: NIZO Food Research B.V., Kernhemseweg 2, 6718 ZB Ede, The Netherlands; Centre for Molecular and Biomolecular Informatics (CMBI), NCMLS, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors: Sacha A F T
authors: SA
authors: van Hijum
authors: Department of Medical Microbiology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands.
authors: Jurgen R
authors: JR
authors: Piet
authors: Department of Molecular Biology & Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors: Nadine
authors: N
authors: Händel
authors: Department of Molecular Biology & Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors: Jan
authors: J
authors: Smelt
authors: Department of Molecular Biology & Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors: Stanley
authors: S
authors: Brul
authors: Department of Molecular Biology & Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; Office for Risk Assessment and Research, Netherlands Food and Consumer Product Safety Authority, Catharijnesingel 59, 3511 GG Utrecht, The Netherlands. Electronic address: B.H.terKuile@uva.nl.
authors: Benno H
authors: BH
authors: ter Kuile
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004252:DNA Mutational Analysis; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D022761:Gene Transfer, Horizontal; D054643:INDEL Mutation; D008826:Microbial Sensitivity Tests; D020641:Polymorphism, Single Nucleotide; D011815:R Factors / Q000235:genetics*; D012641:Selection, Genetic; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D013752:Tetracycline
keywords: Plasmid transfer; Selection regimen; Tetracycline