Selection of CMY-2 producing in the faecal flora of dogs treated with cephalexin

Peter Damborg (1) , Ingrid B. Gaustad (1) , John E. Olsen (1) , Luca Guardabassi (1)

1 Faculty of Life Science [Copenhagen]

Cephalexin is a first generation cephalosporin commonly used in dogs for treatment of pyoderma. The objective of this study was to evaluate the effects of cephalexin on selection of resistant to extended-spectrum cephalosporins. A cohort study was conducted on 13 dogs presenting clinical signs of pyoderma and treated with cephalexin and 22 healthy dogs that had not been treated with antibiotics during the previous six months. Selective plating of faeces on MacConkey agar plates containing cefotaxime (CTX) yielded growth of CTX-resistant for eight of the 13 treated dogs (62%), whereas no growth was observed for any of the control dogs (Fisher Exact test, <0.001). PCR and sequence analysis identified in all eight dogs. PCR-based replicon typing and restriction fragment length polymorphism (RFLP) of transformants revealed location of on indistinguishable IncI1 plasmids in five of the eight dogs. One representative of these five epidemiologically-related IncI1 plasmids was further characterized as sequence type (ST2) by plasmid multilocus sequence typing (pMLST). from the remaining three dogs harboured on distinct plasmids with non-typeable replicons. A single isolate was classified as an extraintestinal pathogenic (ExPEC) due to the presence of , and . The results provide a strong indication that cephalexin selects for producing plasmid-borne CMY-2 β-lactamase. The isolation of a specific IncI1 plasmid carrying from five epidemiologically unrelated dogs suggests that cephalexin use may contribute to the spread of this plasmid lineage among Danish dogs.

Mots clés: antibiotic resistance; antibiotic therapy; AmpC; β-lactams; companion animals

Domaines: Médecine vétérinaire et santé animale

Peter Damborg, Ingrid B. Gaustad, John E. Olsen, Luca Guardabassi. Selection of CMY-2 producing in the faecal flora of dogs treated with cephalexin. Veterinary Microbiology, 2011, 151 (3-4), pp.404. ⟨10.1016/j.vetmic.2011.03.015⟩. ⟨hal-00717089⟩