Isolation of Escherichia coli carrying the blaCTX-M-1 and qnrS1 genes from reproductive organs of broiler breeders and internal contents of hatching eggs.

This study aimed to characterize two third-generation cephalosporins- and quinolone-resistant Escherichia coli (TGCs- and Q-R-Ec) isolates recovered from the ovaries of a broiler breeder flock and the internal contents of hatching eggs produced by the broiler breeder flock. Clonal relatedness was determined by multilocus sequence typing (MLST). The isolates displayed the same multidrug resistance profile, with resistance to ampicillin, ticarcillin, piperacillin, cefazollin, cephalothin, cefotaxime, nalidixic acid, tetracycline and sulfonamides. Double disk synergy test demonstrated that the two isolates presented an ESBL phenotype. PCR and sequencing results showed that both the isolates harbored the blaCTX-M-1 and qnrS1 genes. MLST revealed a novel allele combination, designated as ST461, in these isolates. This study would contribute to the molecular epidemiological understanding of TGCs- and/or Q-R-Ec.