摘要
目的检测粪肠球菌对氟喹诺酮类药物的敏感性，探讨Ⅱ型拓扑异构酶基因突变与耐氟喹诺酮类药物的关系。方法用二倍琼脂稀释法检测6种氟喹诺酮类药物对60株粪肠球菌临床分离株的体外抗菌活性，随机筛选出11株对环丙沙星不同程度耐药菌，PCR扩增gyrA，gyrB，parC，parE基因的喹诺酮耐药决定区（QRDR），产物测序后分析。结果6种药物的相对抗粪肠球菌活性（MIC50，MIC90）从强到弱为：妥舒沙星〉加替沙星，司帕沙星〉左氧氟沙星〉氧氟沙星，环丙沙星；以妥舒沙星抗菌活性最强，氧氟沙星和环丙沙星抗菌活性最差；序列比较发现，有9株耐药株Ⅱ型拓扑异构酶基因发生突变，突变发生在gyrA基因（6株）和parC基因（9株），其中编码gyrA的Ser83→Ile，Arg和编码parC的Ser80→Ile，Arg的密码子表现出高频突变，gyrB和pare编码的氨基酸序列没有改变；未发现gyrA突变单独存在，同时具gyrA和parC突变的MIC值是仅具parC突变菌株MIC值的4倍以上。结论氟喹诺酮类抗菌药新品种妥舒沙星、加替沙星和司帕沙星的抗粪肠球菌活性较老一代药物更强；粪肠球菌对老一代氟喹诺酮类药物存在不同程度的耐药；gyrA基因83，87位突变及parC基因80，84住突变都可引起粪肠球菌对氟喹诺酮类药物产生耐药，但以parC基因80住突变为主；低耐药株往往是parC基因单位点突变，高耐药株同时合并有gyrA基因双位点突变。
Objective To determine the susceptibility of fluoroquinolones against Enterococcus faecalis and study the correlation of type Ⅱ topoisomerase gene mutation to fluoroquinolone resistance. Methods The in vitro activities of 6 fluoroquinolones against 60 clinical isolates of Enterococcus faecalis were compared by the agar dilution mothod. 11 ciprofloxacinresistant strains were selected. The quinolone resistance determining region of gyrA,gyrB,parC and pare genes were amplified and sequenced. Results In decreasing order,the relative activities （MIC50 and MIC90） of 6 fluoroquinolones against Enterococcus faecalis were as follows： tosufloxacin〉gatifloxacin,sparfloxacin〉levofloxacin 〉 ofloxacin and cipfloxaein. Tosufloxacin was the most active while ofloxacin and ciproftoxacin were the least active against Enterococcus faecalis;type I topoisomerase gene mutations oceured in 9 isolates ,which mainly in gyrA（6 strains） and parC（9 strains） genes. The mutations at position 83 in gyrA and 80 in parC leading to the substitution of Serine by isoleucine or arginine were found frequently. No change was observed in the amino acids encoded by gyrB and parE;no single mutation occurred in gyrA. The strains with both gyrA and parC mutations were four times more resistant than the strains which had only parC mutations. Conclusion New fluoroqu inolones such as tosufloxacin,gatifloxacin and sparfloxacin were more active against Enterococcus faecalis than the older flu oroquinolones;Enterococcus faecalis had varying degree of resistance to commonly used fluoroquinolones. The mutations of 83 and 87 condon of gyrA and the mutations of 80 and 84 condon of parC genes were related to fluroqulnolone resistance,and the mutations of 80 condon of parC genes were more important. The low-level fluoroquinolone resistance strains were detected a single mutation in parC gene but high-level fluoroquinolone resistance were associated with simultaneous alterations in both gyrA and parC.
出处
《现代检验医学杂志》
CAS
2010年第2期34-38,共5页
Journal of Modern Laboratory Medicine
关键词
粪肠球菌
氟喹诺酮类药物
最低抑菌浓度
Ⅱ类拓扑异构酶基因突变
Enterococcus faecalis
fluoroquinolone
minimum inhibitory concentration
type Ⅱ topoisomerase gene mutation
作者简介
唐曼娟（1974-），女，硕士，主治检验医师，主要从事细菌耐药性与耐药机制研究，Tel：13786229704，E—mail；moonrlvermj@tom．com。
