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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 detect the resistance of Shigella to quinolone antibiotics, and to explore the correlation between chromosome-mediated DNA gyrase and topoisomerase Ⅳ gene mutation and quinolone resistance in Shigella. Methods Sixty strains of Shigella were tested by agar dilution method. The gyrA, gyrB, parC and parE genes of quinolone resistance-determining region (QRDR) were detected by PCR and the positive products of 20 strains were amplified by PCR The sequencing analysis was carried out. The relationship between gyrA, gyrB, parC gene mutations and quinolone resistance in Shigella was analyzed. Results The resistance rates of 60 strains of Shigella to nalidixic acid, norfloxacin, ciprofloxacin and levofloxacin were 90.0%, 35.0%, 28.3% and 15.0% respectively. The sequencing results showed that the gyrA, gyrB and parC gene mutations Rates were 85%, 30% and 100%, respectively, and no mutations were found in the parE gene. Conclusion Shigella has a serious resistance to quinolones. The target gene mutation is one of the major mechanisms of quinolone resistance. DNA gyrase GyrA gene mutation is the main mutation, followed by DNA topoisomerase IVparC gene mutation.