志贺菌对喹诺酮类抗菌药物耐药性及耐药机制研究

Drug resistance mechanism of fluoroquinolone in Shigellae

目的检测志贺菌对喹诺酮类抗菌药物的耐药情况,探讨染色体介导DNA旋转酶和拓扑异构酶Ⅳ基因突变存在与志贺菌喹诺酮类药物耐药性的相关性。方法用琼脂稀释法对60株志贺菌进行耐药性检测;PCR法检测喹诺酮耐药决定区(QRDR)相关基因gyrA、gyrB、parC、parE,并对其中20株PCR扩增所得的阳性产物进行测序分析;分析志贺菌gyrA、gyrB、parC基因突变与喹诺酮类药物耐药性的关系。结果 60株志贺菌对萘啶酸、诺氟沙星、环丙沙星、左氧氟沙星的耐药率分别为90.0%、35.0%、28.3%和15.0%;测序结果显示gyrA、gyrB、parC基因突变率分别为85%、30%和100%,parE基因未发现突变。结论志贺菌对喹诺酮类耐药严重;靶基因突变是喹诺酮类药物耐药的主要机制之一,以DNA旋转酶GyrA基因突变为主,DNA拓扑异构酶IVparC基因突变次之。

Objective To investigate the prevalence of quinolone-resistance in Shigella strains,and its relation to the DNA mutations of gyrase and topoisomerase Ⅳ genes.Methods Antimicrobial susceptibility tests were performed in 60 Shigella strains by an agar diffusion method.The quinolone resistance determining region（QRDR） of gyrA,gyrB,parC and parE genes were detected by polymerase chain reaction（PCR） and PCR products of 20 strains were analyzed by nucleotide sequencing.We evaluated the correlation between quinolone resistance and the changes of gyrA,gyrB and parC genes statistically.Results 90.0%,35.0%,28.3% and 15.0 % of tested Shigella strains had NAL,NOR,CIP and LVX drug-resistance,respectively.20 Shigella strains were randomly chosen for gene sequencing and gene mutation rates were 85%（17/20）,30%（9/20） and 100%（20/20） for gyrA,gyrB and parC,respectively.There was no mutation confirmed in parE genes.Conclusion The Shigella strains had high frequency of drug resistance to quinolone due to the mutations of gyrA and parC genes.