A high-risk carbapenem-resistant Pseudomonas aeruginosa clone detected in red deer (Cervus elaphus) from Portugal.

Pseudomonas aeruginosa is a ubiquitous bacterium, successfully exploiting a variety of environmental niches due to its remarkable metabolic versatility. The World Health Organization classifies P. aeruginosa as a "priority pathogen" due to its a great ability to overcome the action of antimicrobials, including carbapenems. Hitherto, most studies have focused on clinical settings from humans, but much less on animal and environmental settings, particularly on wildlife. In this work, we report the isolation of a carbapenem-resistant Pseudomonas aeruginosa strain recovered from the faeces of a red deer adult female sampled in a humanized area. This isolate was obtained during a nationwide survey on antimicrobial resistance in wildlife aimed to determine the occurrence of carbapenem-resistant bacteria among 181 widely distributed wild ungulates. This P. aeruginosa isolate was found to be a high-risk clone, belonging to the sequence type (ST) 274. The genomic analysis of P. aeruginosa isolate UP4, classified this isolate as belonging to serogroup O3, which was also found to harbour the genes bla, bla, bla (encoding resistance to beta-lactams), aph(3')-IIb (aminoglycosides resistance), fosA (fosfomycin resistance) and catB7 (chloramphenicol resistance). Antimicrobial susceptibility screening, according to EUCAST, showed resistance to imipenem and intermediate resistance to meropenem and doripenem. To our knowledge, this is the first description of carbapenem-resistant P. aeruginosa in deer in Europe. Our results highlight the importance of wild ungulates either as victims of human activity or amplifiers of AMR, either way with potential impacts on animal, human and ecosystem health, since excretion of AMR bacteria might directly or indirectly contaminate other animals and the surrounding environment, perpetuating the spill-over and chain dissemination of AMR determinants.