[Study on integrons in Escherichia coli which producing extended-spectrum beta-lactamases, isolated from stool specimen of chicken].

Objective: To analysis the dissemination of integrons in the extended-spectrum beta-lactamases (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 integrase. 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 aadA1, aadA2, aadA5, aadA22, dfrA12, dfrA17, dfrI, aar-3 were found in the variable region and aadA gene encodes resistant to streptomycin, spectinomycin, dfr gene to trimethoprim and aar to rifampicin. We realized that aadA22 was the first time detected in China. Class 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.