Detection and characterization of extended-spectrum Beta-Lactamases-Producing "Escherichia coli" in animals

Abstract

The detection of multi-drug 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 ESBL-producing Escherichia coli strains in domestic animal feces in order to assess their antimicrobial resistance profile and carry out molecular characterization of the ß-lactamases. A total of 325 samples were collected from 8 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 cephalosporines; 58.8% resistant to nalidixic acid, ciprofloxacin and trimethoprim/sulphamethoxazole; 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, phosphomycin and colistin. All 34 E. coli strains met criteria for ESBL production. In total, 46 ß-lactamase genes were detected: 43.5% blaTEM, 30.4% blaCTX-M (23.9% blaCTX-M-1 and 6.5% blaCTX-M-9) and 26.1% blaSHV (17.4% blaSHV-5 and 8.7% blaSHV-12). All the ß-lactamases were found in dogs except for 4 blaSHV found in falcons. No pAmpC genes were found. The high prevalence of ESBL-producing E. coli strains in animals could become a zoonotic transmission vector.