Prevalence and quinolone resistance of fecal carriage of extended-spectrum β-lactamase-producing Escherichia coli in 6 communities and 2 physical examination center populations in Shanghai, China

•Fecal ESBL-producing E. coli was detected in 30.5% in the community in Shanghai.•In common with many areas in China, CTX-M-14 was the predominant ESBL in Shanghai.•Horizontal transfer of ESBL genes was achieved in up to 40% of the isolates.•S83 L ± D87N in gyrA and S80I in parC were responsible for quinolone resistance.•Multidrug resistance reiterated the importance of using antibiotics rationally.

ObjectivesTo characterize extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolates from the community, determine their antibiotic sensitivity profiles and quinolone resistance mechanisms, and identify any horizontal transfer of ESBL genes.MethodsOne thousand seven hundred thirty-two stool samples were collected from healthy individuals in 6 communities and 2 physical examination centers in Shanghai, China. ESBL-producing E. coli was screened and confirmed by confirmatory test and E. coli-identifying agars. PCR was used to amplify ESBL-encoding genes blaCTX-M, blaTEM, blaSHV genes, and quinolone resistance-relating genes gyrA, gryB, parC, parE, qnrS, aac (6′)-Ib-cr, oqxA, and oqxB, followed by sequencing. Antimicrobial susceptibility tests and conjugation assays were also performed.ResultsOverall, 528 isolates were identified as ESBL-producing E. coli, and all were positive for blaCTX-M. CTX-M-14 was found most frequently (48.9%). S83 L ± D87N in gyrA and S80I in parC were the most common topoisomerase mutations. Plasmid-mediated quinolone resistance (PMQR) determinants were also detected, including qnrS1 (11.7%), qnrS2 (3.7%), aac (6′)-Ib-cr(12.8%), oqxA(8.5%), and oqxB(11.0%). The rate of multidrug resistance was very high (92.2%). ESBL genes transferred successfully in 39.4% isolates.ConclusionsThere is a high prevalence of fecal carriage of ESBL-producing E. coli in the community in Shanghai, with high-level quinolone resistance and CTX-M-14 being the predominant CTX-M enzyme.