Pseudomonas aeruginosa in French hospitals between 2001 and 2011: back to susceptibility

The European Antimicrobial Resistance Surveillance Network (EARS-Net) reported an increase in the rates of resistance of Pseudomonas aeruginosa to antimicrobials between 2008 and 2011 in France. This alarming report was based on data collected during the harmonisation of breakpoints by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) committee. However, these data were not supported by the findings of other national surveillance networks. In this study, we assessed the trends in P. aeruginosa antimicrobial drug resistance at six French hospitals over a longer period of time (2001-2011) and with a constant definition of resistance. After the exclusion of incomplete data and duplicates, we sorted 34,065 isolates into the antimicrobial resistance patterns defined by the European Centre for Disease Prevention and Control (ECDC). The proportion of isolates with a resistant pattern (non-susceptible to one or two antimicrobial categories), a multidrug-resistant pattern (non-susceptible to three or four antimicrobial categories) or an extensively drug-resistant pattern (non-susceptible to five or six antimicrobial categories) decreased significantly over time. Logically, the proportion of isolates with a wild-type resistance pattern has increased significantly over the same period. No significant changes in the rates of resistance to cephalosporins and penicillins were observed, whereas carbapenem resistance rates increased. By contrast, the proportion of isolates resistant to fluoroquinolones, aminoglycosides and monobactams decreased significantly over time. In conclusion, our data do not confirm the EARS-net data, suggesting instead that antimicrobial drug resistance in P. aeruginosa might not have increased in French hospitals over the last decade.