Wang Ji-jiang, Hu Yi, Jiang Wei-li, Wang Wei-bing, Xu Biao
Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, China.
Zhonghua Liu Xing Bing Xue Za Zhi. 2009 Nov;30(11):1189-93.
To describe the drug resistance-related molecular characterization and clustering feature of rifampicin-resistant (RIFr) M.tuberculosis (M.tb) in rural area of eastern China.
All patients diagnosed as RIFr M.tb in Deqing and Guanyun county during one year period from 2004 to 2005 were included in the study. By proportion method of drug susceptibility test, 65 isolates were identified resistant to rifampicin and regarded as the studied strains. Hotspots of rpoB gene and katG gene were detected by direct DNA sequencing. Beijing genotype M.tb strains were identified by spoligotyping. IS6110-RFLP (IS6110 restriction fragment length polymorphism) and clustering analysis were performed on all RIFr M.tb isolates available.
The mutations in 81 bp rifampicin-resistance determination region (RRDR) of the rpoB gene were observed among 60 (92%) RIFr M.tb isolates, with mutation in locus 531 observed in the majority of RIFr isolates (37/65). 49 (82%) of the 60 isolates were multidrug resistant TB (MDR-TB), which were referred to as resistant to both RIF and isoniazid (INH). Through spoligotyping, 54(83%) isolates were identified as Beijing genotype strains. In clustering analysis of IS6110-RFLP, 24 isolates were grouped into 11 clusters, suggesting that the recent transmission of M.tb did exist among patients. Regarding the drug resistance profile in clusters, all the isolates in clusters were also MDR-TB. 7 clusters contained isolates carrying different mutations were related to RIF-resistance. Multivariate analysis showed the proportion of new cases in clustered patients is higher than that in the un-clustered patients (new/previously treated: OR = 3.342; 95%CI: 1.081 - 10.32).
The acquisition of rifampicin resistance in M.tb was more likely to be resulted from the selective growth of RIFr M.tb in the specific drug resistant M.tb such as isoniazid-resistant M.tb. Previous elongated irregular treatment might favor the epidemic of RIFr M.tb.
描述中国东部农村地区耐利福平结核分枝杆菌（M.tb）的耐药相关分子特征及聚类特征。
纳入2004年至2005年期间在德清县和灌云县诊断为耐利福平M.tb的所有患者。通过药物敏感性试验的比例法，鉴定出65株对利福平耐药的菌株作为研究菌株。通过直接DNA测序检测rpoB基因和katG基因的热点区域。通过间隔寡核苷酸分型（spoligotyping）鉴定北京基因型M.tb菌株。对所有可用的耐利福平M.tb分离株进行IS6110 - 限制性片段长度多态性分析（IS6110 - RFLP）和聚类分析。
在60株（92%）耐利福平M.tb分离株中观察到rpoB基因81bp利福平耐药决定区（RRDR）的突变，大多数耐利福平分离株（37/65）在531位点发生突变。60株分离株中有49株（82%）为耐多药结核病（MDR - TB），即对利福平和异烟肼（INH）均耐药。通过间隔寡核苷酸分型，54株（83%）分离株被鉴定为北京基因型菌株。在IS6110 - RFLP聚类分析中，24株分离株被分为11个簇，表明结核分枝杆菌在患者中确实存在近期传播。关于簇内的耐药谱，簇内所有分离株也均为耐多药结核病。7个簇包含携带不同与利福平耐药相关突变的分离株。多因素分析显示，聚类患者中新发病例的比例高于未聚类患者（新发/既往治疗：比值比=3.342；95%置信区间：1.081 - 10.32）。
结核分枝杆菌对利福平耐药的获得更可能是由于耐利福平M.tb在特定耐药结核分枝杆菌（如耐异烟肼结核分枝杆菌）中的选择性生长所致。既往延长的不规则治疗可能有利于耐利福平M.tb的流行。
