Characterization of CMY-2-type beta-lactamase-producing Escherichia coli isolated from chicken carcasses and human infection in a city of South Brazil

BACKGROUND: Food-producing animals, mainly poultry, have been associated with the maintenance and dissemination of antibiotic-resistant bacteria, such as plasmid-mediated AmpC (pAmpC)-producing Enterobacteriaceae, to humans, thus impacting food safety. Many studies have shown that Escherichia coli strains isolated from poultry and humans infections share identical cephalosporin resistance, suggesting that transmission of resistance from poultry meat to humans may occur. The aim of this study was to characterize pAmpC-producing E. coli strains isolated from chicken carcasses and human infection in a restrict area and to determine their antimicrobial resistance profiles, and molecular type by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). RESULTS: A total of 14 pAmpC-producing E. coli strains were isolated, including eight strains from chicken carcasses and six strains from human infections (from urine, tissue and secretion). The bla(CMY-2) gene was identified in all pAmpC-producing E. coli strains by polymerase chain reaction (PCR) and DNA sequencing. High percentages of strains resistant to tetracycline, nalidixic acid and sulfamethoxazole-trimethoprim (78–92%) were detected, all of which were considered multidrug-resistant. Among the non-beta-lactam resistance genes, the majority of the strains showed tetA, tetB, sulI and sulII. No strain was considered an extended-spectrum beta-lactamases (ESBL) producer, and the bla(TEM-1) gene was found in 2 strains isolated from human infection. Six strains from chicken carcasses and four strains from humans infections were linked to an ISEcp1-like element. Through MLST, 11 sequence types were found. Three strains isolated from human infection and one strain isolated from chicken carcasses belonged to the same sequence type (ST354). However, considerable heterogeneity between the strains from chicken carcasses and humans was confirmed by PFGE analysis. CONCLUSION: This study showed the prevalence of E. coli strains producing bla(CMY-2) linked to ISEcp1 that were present in both chickens and humans in a restricted area. Our results also suggest the presence of a highly diverse strains that harbor pAmpC, indicating no clonal dissemination. Therefore, continuous monitoring and comparative analyses of resistant bacteria from humans and food-producing animals are needed.