Detection and Characterization of Extended-Spectrum Beta-Lactamases-Producing Escherichia coli in Animals

The detection of multidrug-resistant bacteria is a growing problem; however, the role of domesticated animals in the propagation of antimicrobial resistance has barely been studied. The aim of this study was to identify extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains in domestic animal feces to assess their antimicrobial resistance profile and carry out molecular characterization of the β-lactamases. A total of 325 samples were collected from eight animal species. Of these, 34 bacterial isolates were identified as E. coli. The antibiotic resistance profile of the E. coli strains was as follows: 100% resistant to amoxicillin, aztreonam, and cephalosporins; 58.8% resistant to nalidixic acid, ciprofloxacin, and trimethoprim/sulfamethoxazole; 41.2% resistant to gentamicin and tobramycin; 11.8% resistant and 32.4% intermediate to cefoxitin; 97.1% sensible and 2.9% intermediate to amoxicillin/clavulanate; and 100% sensible to ertapenem, minocycline, imipenem, meropenem, amikacin, nitrofurantoin, fosfomycin, and colistin. All 34 E. coli strains met criteria for ESBL production. In total, 46 β-lactamase genes were detected: 43.5% bla_TEM, 30.4% bla_CTX-M (23.9% bla_CTX-M-1 and 6.5% bla_CTX-M-9), and 26.1% bla_SHV (17.4% bla_SHV-5 and 8.7% bla_SHV-12). All the β-lactamases were found in dogs except for four bla_SHV found in falcons. No plasmidic AmpC genes were found. The high prevalence of ESBL-producing E. coli strains in animals could become a zoonotic transmission vector.