Deciphering β-lactamase-independent β-lactam resistance evolution trajectories in Pseudomonas aeruginosa

Show simple item record Cabot, G. Florit-Mendoza, L. Sánchez-Diener, I. Zamorano, L. Oliver, A. 2019-11-14T09:59:43Z
dc.description.abstract [eng] Background: While resistance related to the expression of b-lactamases, such asAmpCfromPseudomonas aeruginosa, has been deeply studied, this work addresses the gap in the knowledge of other potential bacterial strategies to overcome the activity of b-lactamswhen b-lactamases are not expressed. Methods: We analysed b-lactam resistance evolution trajectories in a WT strain and in isogenic mutants either lacking AmpC (AmpC mutant) or unable to express it (AmpG mutant), exposed to increasing concentrations of ceftazidime for 7 days in quintuplicate experiments. Characterization of evolved lineages included susceptibility profiles, whole-genome sequences, resistance mechanisms, fitness (competitive growth assays) and virulence (Caenorhabditis elegans model). Results: Development of resistance was faster for the WT strain but, after 7 days, all strains reached clinical ceftazidime resistance levels. The main resistance mechanism in the WT strain was ampC overexpression, due to mutations in dacB and ampD or mpl. In contrast, ampC overexpression did not evolve in any of the AmpG lineages. Moreover, sequencing of the DAmpC and DAmpG evolved lineages revealed alternative resistance mutations (not seen in WT lineages) that included, in all cases, large (50-600 kb) deletions of specific chromosomal regions together with mutations leading to b-lactam target [ftsI (PBP3)] modification and/or the overexpression or structural modification of the efflux pump MexAB-OprM. Finally, evolved lineages from the AmpC and, especially, AmpG mutants showed a reduced fitness and virulence. Conclusions: In addition to providing new insights into b-lactamresistance mechanisms and evolution, our findings should be helpful for guiding future strategies to combat P. aeruginosa infections.
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dc.relation.isformatof Versió postprint del document publicat a:
dc.relation.ispartof Journal of Antimicrobial Chemotherapy, 2018, vol. 73, num. 12, p. 3322-3331
dc.rights (c) Cabot, G. et al., 2018
dc.subject.classification 57 - Biologia
dc.subject.classification Ciències de la salut
dc.subject.other 57 - Biological sciences in general
dc.subject.other Medical sciences
dc.title Deciphering β-lactamase-independent β-lactam resistance evolution trajectories in Pseudomonas aeruginosa
dc.type info:eu-repo/semantics/article
dc.type info:eu-repo/semantics/acceptedVersion 2019-11-14T09:59:43Z info:eu-repo/date/embargoEnd/2026-12-31
dc.embargo 2026-12-31
dc.rights.accessRights info:eu-repo/semantics/embargoedAccess

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