1. Emergence of extensive-drug-resistant Pseudomonas aeruginosa in a French university hospital.
- Author
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Vettoretti L, Floret N, Hocquet D, Dehecq B, Plésiat P, Talon D, and Bertrand X
- Subjects
- Cluster Analysis, Communicable Diseases, Emerging drug therapy, Communicable Diseases, Emerging epidemiology, Communicable Diseases, Emerging microbiology, Cross Infection epidemiology, Cross Infection microbiology, Dose-Response Relationship, Drug, Drug Resistance, Multiple, Bacterial, Electrophoresis, Gel, Pulsed-Field, France epidemiology, Genotype, Hospitals, University, Humans, Microbial Sensitivity Tests, Molecular Epidemiology, Pseudomonas Infections epidemiology, Pseudomonas Infections microbiology, Pseudomonas aeruginosa enzymology, Pseudomonas aeruginosa genetics, Reverse Transcriptase Polymerase Chain Reaction, Anti-Bacterial Agents pharmacology, Cross Infection drug therapy, Pseudomonas Infections drug therapy, Pseudomonas aeruginosa drug effects, beta-Lactam Resistance genetics
- Abstract
The aim of this study was to describe the molecular epidemiology and the mechanisms of resistance to beta-lactams of emerging extensive-drug-resistant Pseudomonas aeruginosa (XDRPA) in a tertiary-care university hospital over a three-year period. Analysis included antimicrobial susceptibility profiling and pulsed-field gel electrophoresis (PFGE). Resistance mechanisms to beta-lactams were identified: production of naturally occurring and acquired beta-lactamases, overproduction of MexAB-OprM and MexXY efflux systems and loss of porin OprD were assessed. Eighteen patients were colonised or infected with XDRPA which remained susceptible to colistin and, to a lesser extent, to rifampicin. beta-lactam resistance was, in most cases, due to the overproduction of AmpC, overproduction of the MexXY efflux system and loss of porin OprD. One isolate produced the class D extended-spectrum oxacillinase (OXA-ESBL) Oxa-28, but none produced metallo-beta-lactamase (MBL) or class A extended-spectrum beta-lactamase (ESBL). The XDRPA clustered in eight PFGE patterns and both the acquisition and loss of resistance determinants was observed within a single clone during its spread. The emergence of XDRPA isolates in our university hospital has been characterised by genotypic heterogeneity, variation of mechanisms of resistance to beta-lactams in a single clone and the predominance of chromosomally encoded resistance mechanisms.
- Published
- 2009
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