结核分枝杆菌gyrA基因突变与氧氟沙星耐药水平的相关性研究  

Correlation between the levels of ofloxacin resistance and gyr A mutations in Mycobacterium tuberculosis

作　　者：刘志广[1,2] 郭倩[1,2,3] 魏剑浩 赵丽丽[1,2] 蒋毅[1,2] 赵秀芹[1,2] 万康林[1,2] 李桂莲[1,2] 

机构地区：[1]传染病预防控制国家重点实验室传染病预防控制所中国疾病预防控制中心,北京102206 [2]感染性疾病诊治协同创新中心 [3]南华大学病原生物学研究所 [4]温州医学院医学检验省部共建教育部重点实验室

出　　处：《实用预防医学》2015年第6期641-644,共4页Practical Preventive Medicine

基　　金：国家重大传染病专项课题(2013ZX10003002-001);传染病国家重点实验室项目(2014SKLID104)

摘　　要：目的探讨结核分枝杆菌耐药相关基因gyr A突变与氧氟沙星耐药水平之间的相关性。方法采用微孔板Alamar blue显色法检测经比例法确认的39株氧氟沙星耐药和32株氧氟沙星敏感的结核分枝杆菌临床分离株对氧氟沙星的最小抑菌浓度(minimun inhibitory concentration,MIC),基因DNA测序法检测氟喹诺酮耐药相关基因gyr A的突变情况,并用卡方检验检测gyr A基因突变与氧氟沙星耐药水平的相关性。结果 32株氧氟沙星敏感株MIC均<2.000μg/ml且gyr A未发现耐药相关位点突变。氧氟沙星耐药结核分枝杆菌氧氟沙星MIC≥4.000μg/ml的菌株gyr A 94位的突变率(18/24,75%)高于MIC≤2.000μg/ml(6/15,40%)的菌株(P=0.017);5/7的gyr A 91单突变菌株MIC均为2.000μg/ml;两株gyr A94和gyr A90或91位联合突变株氧氟沙星MIC明显高于其它菌株,分别为16.000μg/ml和64.000μg/ml。结论氟喹诺酮耐药菌株gyr A基因94位突变和双位点联合突变与氧氟沙星高水平耐药明显相关,gyr A 91突变与氧氟沙星低水平耐药有关。Objective To explore the correlation between the levels of ofloxacin resistance and mutations of gyrA in Mycobac- terium tuberculosis （M. tuberculosis ）. Methods Microplate Alamar blue assay was used to determine the ofloxacin mini- mum inhibitory concentration （MIC） in 39 ofloxacin resistant and 32 ofloxacin susceptible M. tuberculosis clinical isolates. Direct sequencing was employed to detect mutations of gyrA. Chi - square test was used to evaluate the association between ofloxa- cin resistance levels and mutations in gyrA. Results The MIC of ofloxacin in 32 ofioxacin susceptible M. tuberculosis iso- lates was 〈 2. 000μg/ml and all carried wild type of gyrA. The mutation rate at codon 94 of gyrA was significantly higher in ofloxacin resistant isolates with ofloxacin MIC≥4. 000 μg/ml （75%, 18/24） than in those with ofloxacin MIC ≤2. 000 μg/ml （40% ,6/15） （P=0.017）. The ofloxacin MICs of 5 out of 7 isolates carring single condon mutation of gyrA 91 were all 2.000 μg/ml. Two isolates carring combined mutations of codons 94 and 91 or 90 showed high level resistance to ofloxacin and their ofloxaein MICs were 16. 000 μg/ml and 64. 000 μg/ml, respectively. Conclusions Mutations of gyrA 94 and combined mu- tations in gyrA are significantly correlated with high level resistance to ofloxacin, while mutation of gyrA91 is associated with low level resistance.

关 键 词：结核分枝杆菌 氧氟沙星 最小抑菌浓度 GYRA 

分 类 号：R378[医药卫生—病原生物学]