摘要
目的 分析志贺菌质粒谱、耐药性及流行菌株在遗传学上的同源关系。方法 用改良 Kado Liu 法提取细菌质粒,琼脂糖凝胶电泳检测质粒,用平板稀释法测定药物最低抑菌浓度( M I C) ,用试管内肉汤接合法和平板表面接合法进行接合转移试验。结果 130 株志贺菌都含有5 条小质粒带( 除1 条分子量稍大于6 ×106 外,其余4 条均小于6 ×106) ,128 株含有1 条分子量约为120 ×106 的大质粒带,18 株有1 或2 条分子量介于34 ~80 ×106 之间的质粒带;15 种抗生素的 M I C 测定结果显示,这些菌株对头孢三嗪、阿米卡星、头孢哌酮、头孢唑啉,庆大霉素敏感( 敏感率为100 % ~88 .6 % , M I C90为< 2 ~10 μg/ml) ,对卡那霉素等其余10 种药物的敏感率很低或不敏感,不同质粒谱菌株对药物的敏感性几乎相同,对包括18 株含34 ~80 ×106 质粒在内的25 株菌进行接合转移试验,未检出传递性耐药性质粒。结论 细菌的耐药性由非传递性的小质粒所携带,且大多流行菌株在遗传学上具有同源性相关。
Objective To analyze the plasmid profiles, drug resistant activities and genetically homologous correlationship of 130 strains of Shigella.Methods Agarose gel electrophoresis analysis was used to detect plasmid profiles. Plate transconjugation and broth transconjugation were used to examine the conjugative resistant plasmids and the agar plate dilution method was used to analyze the minimum inhibitory concentration (MIC) of 15 antimicrobial agents. Results All (130) strains contained 5 small molecular weight plasmids. (One was larger than 6×10 6 and the other four were smaller thant 6×10 6) 128 strains contained a large plamised (about 120×10 6) and 18 strains harbored one or two middle sized plasmids (34~80×10 6). The results of MIC of 15 antimicrobial agents showed that all the strains were sensitive to ceftriaxone, amikacin, cefoperazone cefazolin and gentamycin. The susceptibility rates were in the range of 100%~88.6%. The range of MIC 90 was<2~ 10 μg/ml. The susceptibility rates of the strains to other 10 agents were nearly or equal to 0%. Different plasmid profile strains had almost the same antimicrobial susceptibilities. 25 strains (including 18 strains harboring 34~80×10 6 plasmids) selectively examined to have no self transmissible conjugative plasmid.Conclusion Drug resistant activities of the Shigella were carried by the small plasmids and most of the strains had geneticlally homologous correlation.
基金
浙江省教委基金
关键词
志贺氏菌
质粒
耐药性
痢疾
细菌性痢疾
Shigella dysenteriae Drug resistance, microbial Plasmids