2009～2013年齐齐哈尔市粪肠球菌基因序列进化研究及耐药性分析

An evolutionary study of the gene sequences and drug resistance of Enterococcus faecalis in Qiqihar from 2009 to 2013

目的研究化脓性胆管炎患者胆汁培养粪肠球菌基因序列,分析其对6种氟喹诺酮类药物的耐药性。方法对2009~2013年齐齐哈尔医学院附属三院ERCP治疗的化脓性胆管炎患者胆汁标本分离的60株粪肠球菌进行基因序列分析,并利用琼脂稀释法检测分离菌对6种氟喹诺酮类药物（FQs）的MIC50,MIC90和耐药率。结果本组粪肠球菌对6种氟喹诺酮类药物耐药率分别为：莫西沙星15.0%,加替沙星18.3%,左氧氟沙星25.0%,氧氟沙星和环丙沙星均为35.0%,诺氟沙星48.3%。粪肠球菌耐药株中的gyrA在喹诺酮类药物耐药决定区的第83位和87位氨基酸发生突变,分别为S83I,E87G。parC第80位氨基酸发生突变S80I,产生对氟喹诺酮类药物耐药。结论莫西沙星和加替沙星对粪肠球菌具有良好的抑制作用,但由于部分粪肠球菌菌株基因已发生突变,其耐药性还需进一步观察,同时还需开发更有效的具有抑制此类细菌DNA促旋酶和拓扑异构酶Ⅳ的氟喹诺酮类药物。

Objectives To study the gene sequences of Enterococcus faecalis in cultures of bile from patients with suppurative cholangitis and to analyze resistance to 6fluoroquinolones（FQs）. Methods The gene sequences of 60strains of E.faecalis were analyzed.These strains were isolated from patients at the Third Hospital Affiliated with Qiqihar Medicine University in Qiqihar from 2009-2013.The MIC50,MIC90,and rate of drug resistance to 6FQs were determined using the agar dilution method. Results Resistant strains had mutations of amino acid 83and amino acid 87in the quinolone resistance-determining regions（QRDRs）of the gyrA gene（S83Iand E87G,respectively）.Mutation of amino acid 80（S80I）in the ParC gene produced drug resistance to FQs.E.faecalis had resistance to moxifloxacin of15%,resistance to gatifloxacin of 18.3%,resistance to levofloxacin of 25%,resistance to ofloxacin and ciprofloxacin of35%,and resistance to norfloxacin of 48.3%. Conclusion Moxifloxacin and gatifloxacin satisfactorily inhibited E.faecalis but there were mutations of genes in some strains.The drug resistance of E.faecalis still needs to be monitored,and new FQs need to be developed to inhibit the DNA gyrase and topoisomerase IV genes of this bacterium.