RESUMO
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 blaCMY-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 blaTEM-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 blaCMY-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.
Assuntos
Resistência às Cefalosporinas/genética , Galinhas/microbiologia , Farmacorresistência Bacteriana/genética , beta-Lactamases/genética , Animais , Brasil , Eletroforese em Gel de Campo Pulsado , Escherichia coli/genética , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Microbiologia de Alimentos , Genes Bacterianos , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Plasmídeos , Aves Domésticas/microbiologia , ZoonosesRESUMO
BACKGROUND: Enteropathogenic Escherichia coli (EPEC) are classified into typical and atypical strains based on the presence of the E. coli adherence factor (EAF) plasmid. The EAF plasmid contains the bfp (bundle-forming pilus) operon and the perABC (plasmid encoded regulator) gene cluster. A 1-kb cryptic region of EAF plasmid has been widely used as a genetic probe for EPEC detection. However, some EPEC strains may harbor an EAF plasmid lacking the EAF probe sequence, which makes the differentiation between typical and atypical a complex task. In this study, we report the genetic analysis of the EAF plasmid-encoded genes in a collection of EPEC clinical isolates. METHODS: A total of 222 EPEC clinical isolates, which were previously classified as typical (n=70) or atypical (n=152) by EAF probe reactivity, were screened for the presence of different EAF sequences by PCR and DNA hybridization. RESULTS: All typical strains possessed intact bfpA and perA genes, and most of them were positive in the PCR for EAF probe sequence. However, a subset of 30 typical strains, 22 of which belonged to O119 serogroup, presented a 1652 pb deletion in the region between 1093-bp downstream perC and 616-bp of the EAF fragment. The bfpA, bfpG, and per genes were found in all typical strains. In addition, 32 (21%) atypical strains presented the perA gene, and 20 (13.2%) also presented the bfpA gene. Among the 32 strains, 16 belonged to the O119:H2, O119:HND, and ONT:HND serotypes. All 32 atypical strains contained perA mutation frameshifts and possessed an IS1294 element upstream of the per operon as detected by PCR followed by restriction fragment length polymorphism (RFLP) typing and multiplex PCR. Among the 20 bfpA probe-positive strains, eight O119 strains possessed deletion in the bfp operon at the 3'end of bfpA due to an IS66 element. CONCLUSION: Our data show that typical O119 strains may contain a deletion within the EAF probe sequence not previously reported. This new finding suggests that care should be taken when using the previously described EAF PCR assay in epidemiological studies for the detection of typical O119 strains. In addition, we were able to confirm that some atypical strains carry vestiges of the EAF plasmid.