Study on integrons in Escherichia coli which producing extended-spectrum β-lactamases,isolated from stool specimen of chicken / 中华流行病学杂志

ABSTRACT

Objective To analysis the dissemination of integrons in the extended-spectrumβ-laetamases(ESBLs)producing Escherichia coli,isolated from stool specimen of chicken and to study the relations between the resistance and the integrons of these isolates.Methods The Escherichia coli isolates were collected from Gansu,Hubei,Sichuan provinces and Beijing municipal city，and were isolated from stool specimen of chickens.Using WHONET software,the Escherichia coli producing ESBLs were selected，and then detected by PCR method class 1,2,3,4 integrmse.PCR products of the variable region of the integron were sequenced.Results 54 of the 224(24.1％)isolates were ESBLs producing Escherichia coli.Class 1 integron were detected in 63.0％of the isolates,and aadAl,aadA2,aadA5,aadA22,dfrAl2,dfrA17,dfrI,aar-3 were found in the variable region and aad A gene encodes resistant to streptomycin，spectinomyein,dfr gene to trimethoprim and aar to rifampicin.We realized that aadA 22 was the first time detected in China.C1ass 2 integron were detected in 5.6％ of the isolates,Class 3 integron was detected in 3 isolates.Conclusion Class 1 integron Was the most commonly seen integron in Escherichia coli,encoding the resistance to streptomycin.spectinomycin and trimethoprim.Integrons were contributed to the horizontal transfer of resistant genes in the same or different species,suggesting that the antimicrobial resistance and the dissemination of integrons should be monitored.