肺炎克雷伯菌对喹诺酮类及氨基糖苷类耐药基因检测及耐药机制分析

Detection of antimicrobial-resistant genes of klebsiella pneumoniae resistant to quinolones and aminoglycoside and drug resistant mechanism

目的了解临床分离的耐环丙沙星及庆大霉素肺炎克雷伯菌喹诺酮类耐药基因qnrA、qnrB、qnrS、qepA与氨基糖苷类耐药基因aac(6′)-Ⅰb的携带情况,并进行相关耐药机制分析。方法采用VITEK-2型全自动微生物检测系统鉴定细菌;采用K-B法检测细菌对16种常用抗菌药物的敏感性;采用聚合酶链反应检测耐药基因qnrS、qnrA、qnrB、qepA和aac(6′)-Ⅰb。结果 25株耐环丙沙星和庆大霉素的肺炎克雷伯菌中,12株(48.0%)检出aac(6′)-Ⅰb基因,7株(28.0%)检出qnrS基因,4株(16.0%)检出qnrB基因,未检出qnrA和qepA基因,其中1株同时检出qnrS和qnrB基因,qnr基因总的阳性率为40.0%;有6株肺炎克雷伯菌同时存在喹诺酮类和氨基糖苷类耐药基因(50.0%)。结论对环丙沙星和庆大霉素耐药的肺炎克雷伯菌携带aac(6′)-Ⅰb和qnrS、qnrB耐药基因,qnr基因的携带率高达40.0%,肺炎克雷伯菌对氨基糖苷类药物耐药主要由aac(6′)-Ⅰb引起,单株菌可同时存在多种耐药基因,从而介导对多种抗菌药物的耐药性。

OBJECTIVE To detect qnrA,qnrB,qnrS and qepA and aminoglycoside modifying enzymes（AMES） gene in clinical isolates of Klebsiella pneumoniae resistant to cinrofloxacin and gentamicin,and study the resistant mechanism.METHODS These isolates were identified by the automatic VITEK2 system and their antimicrobial susceptibility was tested by K-B method.The drug resistant genes were analyzed by polymerase chain reaction.RESULTS Among K.pneumoniae resistant to cinrofloxacin and gentamicin,the positive rates of qnrS,qnrB,qnrA,qepA and aac（6′）-Ⅰb gene were 28.0%,16.0%,0%,0%,and 48.0%,respectively.CONCLUSION K.pneumoniae isolates carry aac（6′）-Ⅰb,qnrS and qnrB gene,qnrA and qepA gene are not found.The carrying rate of qnr is 40.0%,aac（6′）-Ⅰb and qnr may be the main resistant mechanism of K.pneumoniae to aminoglycoside and quinolones.but multi-drug resistant genes exist in a singal strain,which can induce the multi-drug resistance.