A ten-year microbiological study of Pseudomonas aeruginosa strains revealed diffusion of carbapenems and quaternary ammonium compounds resistant populations

Pseudomonas aeruginosa is one of the leading causes of healthcare-associated infections. For this study, the susceptibility profiles to antipseudomonal antibiotics and a quaternary ammonium compound, didecyldimethylammonium chloride (DDAC), widely used as a disinfectant, were established for 180 selected human and environmental hospital strains isolated between 2011 and 2020. Furthermore, a genomic study was performed to determine their resistome and clonal putative relatedness. During the ten-year study period, it was estimated that 9.5% of clinical P. aeruginosa were resistant to carbapenem, 11.9% presented an MDR profile, and 0.7% an XDR. Decreased susceptibility (DS) to DDAC was observed for 28.0% of strains that was significantly more associated with MDR and XDR profiles and from hospital environmental samples (p <0.0001). According to genomic analyses, the P. aeruginosa population unsusceptible to carbapenems and/or to DDAC was diverse but mainly belonged to top ten high-risk clones described worldwide. The carbapenem resistance appeared mainly due to the production of the VIM-2 carbapenemase (39.3%) and DS to DDAC mediated by MexAB-OprM pump efflux overexpression. This study highlights the diversity of MDR/XDR populations of P. aeruginosa which are unsusceptible to molecules that are widely used in medicine and hospital disinfection and are probably distributed in hospitals worldwide.