喹诺酮类耐药福氏志贺菌的相关耐药基因研究  

Genes conferring quinolone resistance in Shigella flexneri

作　　者：张雯霞[1] 张珏[1] 陈洪友[2] 屠丽红[2] 陈敏[2] 

机构地区：[1]上海中医药大学附属曙光医院检验科,上海201203 [2]上海市疾病预防控制中心细菌检测实验室

出　　处：《中国感染与化疗杂志》2017年第1期46-51,共6页Chinese Journal of Infection and Chemotherapy

基　　金：基金项目:上海市公共卫生重点学科卫生微生物学(12GWZX0801)

摘　　要：目的了解2010—2014年上海市各区县医院139株福氏志贺菌的耐药性,探讨福氏志贺菌对喹诺酮类药物的耐药机制。方法用纸片扩散法测定菌株对14种抗菌药物的敏感性,用环丙沙星E试验条测定其最低抑菌浓度;采用PCR法检测DNA旋转酶A亚单位(gyrA)、拓扑异构酶ⅣC亚单位(parC)基因的喹诺酮类药物耐药决定区(QRDR),同时对质粒介导喹诺酮类耐药(PMQR)基因qnrA、qnrB、qnrS和氨基糖苷乙酰转移酶变异基因aac(6')-Ib-cr进行筛选。扩增产物进行DNA测序。结果福氏志贺菌对氨苄西林、链霉素、四环素、萘啶酸的耐药率都达到了90%以上,对环丙沙星的耐药率达到了40.3%,同时有30.2%菌株对头孢吡肟产生了耐药。gyrA和parC基因的突变率分别为98.6%和97.8%。gyrA基因存在Ser83、Asp87和His211 3个位点的突变,parC基因只检测到Ser80 1个位点的突变;共检测到9株qnrS和6株aac(6')-Ib-cr喹诺酮耐药质粒。结论上海地区福氏志贺菌耐药情况严重。QRDR相关基因突变率高,Asp87的突变对喹诺酮类抗菌药物的耐药起着主导作用,而耐药质粒起着重要的辅助作用。Objective To investigate the antimicrobial resistance profile of Shigella flexneri in Shanghai from 2010 to 2014 and examine the mechanism of fluoroquinolone resistance. Methods Kirby-Bauer method was used to determine the susceptibility of the S. flexneri strains to 14 antibiotics. The minimum inhibitory concentration （MIC） of ciprofloxacin was tested by E-test. Mutations within quinolone resistance determining regions （QRDR） of gyrA and parC and plasmid-mediated quinolone resistance （PMQR） genes, qnrA, qnrB, qnrS and aac（6）-Ib-cr were identified by polymerase chain reaction （PCR）. All the products were subjected to sequencing analysis. Results More than 90% of the 139 S. flexneri isolates were resistant to ampicillin, streptomycin, tetracycline, and nalidixic acid, 40.3 % to eiprofloxacin and 30.2 % to cefepime, respectively. Genetic mutation of gyrA and parC was found in 98.6 % and 97.8 % of the strains, respectively. Three point mutations （Ser83, Asp87 and His211） were detected in gene gyrA and one point mutation （Ser80） was found in in gene parC. Plasmid-mediated resistant gene qnrS was found in 9 strains and aac（6＇）-Ib-cr in 6 strains. Conclusions The antibiotic resistance of S. flexneri is serious in Shanghai. The mutation rate within QRDR is high. Point mutation in Asp87 of gyrA is the main mechanism of quinolone resistance. The plasmid-mediated quinolone-resistant genes also play an important supplementary role.

关 键 词：志贺菌 喹诺酮类 耐药基因 

分 类 号：R446.5[医药卫生—诊断学] R440[医药卫生—临床医学]