鸡源肠杆菌质粒介导喹诺酮类耐药基因检测

Detection of Plasmid-Mediated Quinolone Resistance in Clinical Isolates of Enterobacteriaceae from Avian

【目的】对广东地区分离得到的鸡源肠杆菌进行质粒介导喹诺酮类耐药(PMQR)基因检测。【方法】采用纸片扩散法对84株鸡源肠杆菌临床分离株进行27种抗菌药物的敏感性测定。通过PCR检测质PMQR基因qnr、qepA和aac(6′)-Ib-cr。研究PMQR基因阳性菌株染色体gyrA、gyrB、parC、parE基因喹诺酮耐药决定突变区(QRDRs)的变异情况。【结果】84株鸡源肠杆菌对兽医临床常用的恩诺沙星、氟罗沙星、氨苄西林、复方新诺明、强力霉素以及利福平、链霉素、罗红霉素的耐药率很高,且为多重耐药;对氨苄西林/舒巴坦、氨曲南、多粘菌素E和头孢氨苄的敏感性高。在84株鸡源肠杆菌中检测到1株同时携带qnrB和aac(6′)-Ib-cr基因的肺炎克雷伯氏杆菌GDK05,整个qnrB基因的阅读框架与GenBankTM中的qnrB6一致,同时GDK05在gyrA基因的QRDR出现83位S→I变异,gyrB、parC、parE基因的QRDRs没有检测到变异。【结论】广东地区集约化养殖场鸡源肠杆菌对兽医临床常用抗菌药物耐药严重。本研究首次在兽医临床上检测到1株同时携带qnrB6和aac(6′)-Ib-cr基因的鸡源肺炎克雷伯氏菌。PMQR机制的出现预示着喹诺酮类耐药很可能会在兽医临床上更加快速而广泛地传播。

[Objective] To detect plasmid-mediated quinolone resistance （PMQR） qnr, qepA, aac （6＇）-Ib-cr genes in clinical isolates of Enterobacteriaceae from avian in Guangdong province. [Method] Susceptibility of 84 strains to 27 antimierobial agents were determined by agar disc diffusion method. All of the 84 strains were screened for the qnr, qepA, aac （6＇）-Ib-cr genes by PCR. Mutations in the quinolone-resistance-determining region （QRDRs） of the gyrA, gyrB, parC andparE gene was detected in PMQR positive strains. [Result] The isolates showed high rate of resistance to antimicrobial agents widely used in veterinary clinical medicine such as exrofloxacin, fleroxacin, ampicillin, trimethoprim-sulfamethoxazole, doxycycline, and rifampin, streptomycin and roxithromycin. All of the 84 strains showed multiple-resistance to at least 6 drugs. However most of them were sensitive to ampicillin-sulbactam, aztreonam, polymyxin E and cephalexin. A qnrB6 and aac （6＇）-Ib-cr gene was identified in a Klebsiella pneumoniae. Mutation of S→I occurred in the QRDR of the gyrA 83 site, while no mutations were detected in QRDRs ofgyrB, parC andparE. [Conclusion] Enterobacteriaceae isolated from avian in Guangdong showed high level multiple-resistance to widely used drugs. This is the first report on two PMQR determinants, qnr and aac （6＇）-Ib-cr, in clinical isolates of Kpneumoniae from avian. The emergency of PMQR genes may indicate a more widespread dissemination of resistance to quinolones in avian industry.