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. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was financially supported by Normandy Regional Council and French Ministry of Agriculture (EcoAntibio Plan) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethic committee of CHU Caen Normandie reviewed and approved the study number ID 3784 I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors