Distribution of Extended-Spectrum β-lactamases and AmpC β-lactamases-producing Enterobacteriaceae in Urban and Rural Areas in Shandong, China

Abstract

Background/Aim: Antimicrobial consumption in China showed significant geographic distinction. This study aimed to investigate antimicrobial resistance and epidemiology of extended-spectrum β-lactamase (ESBLs), AmpC β-lactamases(ACBLs)-producing Enterobacteriaceae isolated from healthy populations in rural and urban areas in Shandong province, China. Methods: We recruited 332 healthy people in urban and rural areas between 2012 to 2013. Fecal samples were collected and the isolates were identified to the species level. Antimicrobial susceptibility testing was performed by reference Kirby-Bauer method as described by NCCLS. Eighteen commonly used antimicrobial agents was tested. The double-disc synergy test, Etest and agar diffusion tests were used as screening tests to detect ESBLs. All the cefoxitin resistant isolates were subjected to determine ACBLs by combined disc diffusion test and modified three-dimensional test. Results: Escherichia coli composed 76.9% of 351 isolated Enterobacteriaceae, followed by Klebsiella pneumoniae (19.4%). Participants were divided into three groups (adult, primary school and kindergarten children). The prevalence of ESBLs for each group was 6.8%, 15.9%, 25.0% in urban populations and 66.0%, 61.2%, 75.1% in rural populations respectively. Besides, the prevalence of ACBLs in those groups was 9.2%, 10.0%, 3.0% and 21.2%, 16.0%, 14.1%. Overall, sulfamethoxazole, amoxicillin and ampicillin were three major antibiotics which 85%-100% isolates exhibited resistance to. The prevalence of faecal carriage of ESBLs and ACBLs -producing Enterobacteriaceae was significantly higher in rural areas than urban areas. In urban areas, there is a tendency for younger to have higher rate of ESBLs-producing Enterobacteriaceae compared to adults. Conclusions: Our results indicated that antimicrobial resistance in rural areas was more severe than urban areas which may arise from differences in antibiotic regulation and medication patterns. This finding has public health implications for selecting vulnerable populations, given the antibiotic abuse in China, especially in rural areas, and the age-specific difference on ESBLs distribution in urban areas.