Resistance of Animal Strains of to Carbapenems.

Carbapenems are major antibiotics reserved to human medicine. This study aimed to investigate the mechanisms of carbapenem resistance of a selection of veterinary strains from the French network Resapath. Thirty (5.7%) imipenem and/or meropenem non-susceptible of canine ( = 24), feline ( = 5), or bovine ( = 1) origin were identified in a large collection of 527 veterinary strains gathered by the Resapath. These resistant isolates belonged to 25 MultiLocus Sequence Types (MLST), of which 17 (68%) are shared with clinical (human) strains, such as high risk clones ST233 and ST395. Interestingly, none of the veterinary strains produced a carbapenemase, and only six of them (20%) harbored deletions or insertion sequence (IS) disrupting the porin OprD gene. The remaining 24 strains contained mutations or IS in various loci resulting in down-regulation of gene coupled with upregulation of efflux system CzcCBA ( = 3; activation of sensor kinase CzcS ± CopS), MexEF-OprN ( = 4; alteration of oxido reductase MexS), MexXY ( = 8; activation of two-component system ParRS), or MexAB-OprM ( = 12; alteration of regulator MexR, NalC ± NalD). Two efflux pumps were co-produced simultaneously in three mutants. Finally, in 11 out of 12 strains displaying an intact porin OprD, derepression of MexAB-OprM accounted for a decreased susceptibility to meropenem relative to imipenem. Though not treated by carbapenems, animals thus represent a reservoir of multidrug resistant strains potentially able to contaminate fragile outpatients.