耐碳青霉烯类肠杆菌科细菌对喹诺酮类耐药机制的研究

目的研究质粒介导喹诺酮耐药(PMQR)基因在耐碳青霉烯类肠杆菌(CRE)中的流行情况及耐药机制。方法收集2015年3月—2018年3月某院临床分离的CRE菌株,VITEK2 Compact分析仪对其进行鉴定及药物敏感试验,采用聚合酶链反应(PCR)及测序确定PMQR基因qnrA、qnrB、qnrS、qepA、acc(6’)Ib-cr携带情况,通过质粒接合试验验证PMQR基因的水平转移。结果耐碳青霉烯类大肠埃希菌对喹诺酮类药物的耐药率达100%,耐碳青霉烯类肺炎克雷伯菌对喹诺酮类药物的耐药率为15.56%～33.33%。acc(6’)Ib-cr基因检出率最高(87.72%),其次为qnrB(77.19%)和qnrS(17.54%),有2株菌携带qnrA基因(3.51%),未分离出qepA基因,菌株同时含有2种或3种PMQR基因(84.21%)。8株接合成功的菌株均存在PMQR基因转入,但喹诺酮药物对其最低抑菌浓度无明显改变。结论虽然该院CRE质粒介导喹诺酮耐药基因检出率高,但对喹诺酮类药物仍存在一定敏感性。

Mechanisms of quinolone resistance of carbapenem-resistant Enterobacte-riaceae

Objective To study the prevalence of plasmid-mediated quinolone resistance (PMQR) genes in carbapenem-resistant Enterobacteriaceae (CRE) and its resistance mechanism. Methods Clinically isolated CRE strains in a hospital from March 2015 to March 2018 were collected, then identified and performed antimicrobial susceptibility test by VITEK 2 Compact analyzer, carriage of PMQR genes qnrA, qnrB, qnrS, qepA and acc (6')Ib-cr were determined by polymerase chain reaction (PCR) and sequencing, the horizontal transfer of PMQR genes were verified by plasmid conjugation test. Results Resistance rates of carbapenem-resistant Escherichia coli and carbapenem-resistant Klebsiella pneumoniae to quinolones were 100% and 15.56%-33.33% respectively. Detection rate of acc (6')Ib-cr gene was the highest (87.72%), followed by qnrB (77.19%) and qnrS (17.54%), 2 strains (3.51%) carried qnrA gene, qepA gene was not isolated, 84.21% of strains harbored 2 or 3 PMQR genes. PMQR gene was transfected into all the 8 conjugated strains, but minimum inhibitory concentration value of quinolones didn't change significantly. Conclusion The detection rate of PMQR genes in CRE in this hospital is high, but there is a certain sensitivity to quinolones.