Extended-spectrum β-lactamases belonging to CTX-M group produced by Escherichia coli strains isolated from companion animals treated with enrofloxacin

We studied the antibiotic resistance among Escherichia coli isolates obtained from fecal samples of dogs and cats treated and untreated with enrofloxacin in veterinary clinics. Resistant patterns of 70 strains and the presence of extended-spectrum β-lactamase (ESBL) were studied. The genes encoding the following families of β-lactamases: CTX-M, GES, PER, TEM and SHV, were investigated by PCR-RFLP and sequencing. The strains isolated from enrofloxacin-treated animals were multi-drug-resistant exhibiting resistant patterns including fluorquinolones, β-lactams, aminoglycosides, tetracycline and phenicols. On the contrary, the strains obtained from the untreated group of animals exhibited narrower antibiotic resistant profiles. The synthesis of ESBL was detected in 14 strains (20%) isolated from treated animals. The ESBL encoded by genes blaCTX-M-1, blaCTX-M-9 group and blaPER-2 were detected by PCR. We believe that this is the first report on the presence of ESBL in E. coli strains isolated from small animals in Chile, and the first report of β-lactamase belonging to the CTX-M-9 group (CTX-M-14). The presence of these genes in bacteria isolated from pets is an important fact that constitutes a public health concern.