title: Dynamics of Mutations during Development of Resistance by Pseudomonas aeruginosa against Five Antibiotics.
abstract: Pseudomonas aeruginosa is an opportunistic pathogen that causes considerable morbidity and mortality, specifically during intensive care. Antibiotic-resistant variants of this organism are more difficult to treat and cause substantial extra costs compared to susceptible strains. In the laboratory, P. aeruginosa rapidly developed resistance to five medically relevant antibiotics upon exposure to stepwise increasing concentrations. At several time points during the acquisition of resistance, samples were taken for whole-genome sequencing. The increase in the MIC of ciprofloxacin was linked to specific mutations in gyrA, parC, and gyrB, appearing sequentially. In the case of tobramycin, mutations in fusA, HP02880, rplB, and capD were induced. The MICs of the beta-lactam compounds meropenem and ceftazidime and the combination of piperacillin and tazobactam correlated linearly with beta-lactamase activity but not always with individual mutations. The genes that were mutated during the development of beta-lactam resistance differed for each antibiotic. A quantitative relationship between the frequency of mutations and the increase in resistance could not be established for any of the antibiotics. When the adapted strains are grown in the absence of the antibiotic, some mutations remained and others were reversed, but this reversal did not necessarily lower the MIC. The increased MIC came at the cost of moderately reduced cellular functions or a somewhat lower growth rate. In all cases except ciprofloxacin, the increase in resistance seems to be the result of complex interactions among several cellular systems rather than individual mutations.
authors.affiliation: Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Biology & Applied Bioinformatics, Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Martijs J
authors.initials: MJ
authors.lastname: Jonker
authors.affiliation: Biology & Applied Bioinformatics, Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Moustakas
authors.affiliation: Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Stanley
authors.initials: S
authors.lastname: Brul
authors.affiliation: Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands Office for Risk Assessment and Research Coordination, Netherlands Food and Consumer Product Safety Authority, Utrecht, The Netherlands B.H.terKuile@uva.nl b.h.terkuile@nvwa.nl.
authors.forename: Benno H
authors.initials: BH
authors.lastname: Ter Kuile
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D010878:Piperacillin / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D013845:Thienamycins / Q000494:pharmacology; D014031:Tobramycin / Q000494:pharmacology; D001618:beta-Lactamases / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D013845:Thienamycins; D047090:beta-Lactams; D002939:Ciprofloxacin; D002442:Ceftazidime; D001618:beta-Lactamases; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D000077731:Meropenem; D014031:Tobramycin; D010878:Piperacillin