志贺菌GyrA基因突变与耐药相关性研究

收集 1 1 4株志贺菌流行株 ,分别作血清分型和检查对喹诺酮类药物的敏感性 ;PCR扩增耐药相关的GyrA基因片段 ,作单链构象多态性 (single strandconformationpolymorphism ,SSCP)分析和序列测定 ;最终研究突变与喹诺酮类耐药的相关性。结果发现我国志贺菌流行株仍以福氏志贺菌为主 ,约占 98 2 % ;大多数福氏志贺菌株对环丙沙星、诺氟沙星高度敏感 ,敏感率分别为81 2 5 %和 74 1 % ;流行株GyrA基因耐药相关片段与野生菌株相比 ,部分菌株出现C( 2 4 8) T单位点突变或C( 2 4 8) T和A( 2 60 ) G双位点突变 ;卡方检验显示 ,C( 2 4 8) T单位点突变基础上增加A( 2 60 ) G点突变与环丙沙星、诺氟沙星耐药相关 ,故A( 2 60 ) G可作为耐药监测位点 ;另外 ,可用SSCP分析PCR扩增的GyrA基因耐药相关片断 ,作为GyrA基因耐药突变的粗筛方法。

Shigella GyrA Mutations and their Relations with Quinolones Resistance

114epidemic Shigella strains were serotyped and their sensitivities to quinolones were tested. A 341bp GyrA segment was amplified by PCR. The PCR products were analyzed by SSCP and sequenced. The relations between GyrA mutations and quinolones resistence were studied. The epidemic strains are mainly S. flexneri , with ratio about 98.2%. Most S. flexneri strains are sensitive to ciprofloxacin and norfloxacin, with ratio of sensitivity 81 25% and 74 1% respectively. According to the sequencing result, some strains have C(248) T single point mutation or C(248) T and A(260) G dual mutations. The A(260) G mutation has a statistical relation with the resistance to ciprofloxacin or norfloxacin and can be regarded as a inspecting point. In detecting GyrA mutations, SSCP is effective and can be a riddling method.