大肠埃希菌AmpC酶的临床实验室检测与报告

Identification and report of AmpC β-lactamase in Escherichia coli

目的探讨致病大肠埃希菌AmpC酶的临床实验室检测方法,为临床合理使用抗生素提供科学依据。方法将纸片扩散法药敏试验中对头孢西丁中介或耐药的菌株采用三维试验和聚合酶链反应(PCR)基因扩增对AmpC酶进行确证试验。结果临床分离筛选的10株耐头孢西丁大肠埃希菌中采用三维试验和PCR基因扩增后1株被确证为AmpC酶菌株。结论耐头孢西丁的革兰阴性菌需要作AmpC酶试验或PCR基因扩增进行确证,准确AmpC酶检测结果对临床合理使用抗生素具有积极意义。

Objective To investigate the methods of detecting Escherichia coli producing AmpC β-lactamase. Methods A total of 10 clinical isolates of non-repeated Escherichia coli were collected from different hospitals in Shanxi province. AmpC β-lactamase producing isolates were identified by cefoxitin three-dimensional test and antibiotic susceptibility was identified by agar dilution test. Plasmid extraction and PCR amplification of corresponding group was performed, followed by sequencing. Results The positive rate of cefoxitin three-dimensional test was 10%. The susceptibility test showed that all strains were resistant to cephamycins and piperacillin, and susceptible to imipenem. One strain of Escherichia coli was confirmed producing resistance to fourth-generation cephalosporin. Conclusion Escherichia coli which produces both ESBL,AmpC and clavulanate may induce hyper production of the AmpC β-laetamase leading to hydrolysis of the third generation cephalosporin thus masking any synergy arising from inhibition of the ESBL. So the Escherichia coli isolates of which disk diffusion screening test are positive should be confirmed by the PCR. Carbapenems could be the first choice for the treatment of infection caused by AmpC-lactamase producers.