胞内分枝杆菌临床分离株耐药谱及基因型特征研究

Antimicrobial Susceptibility and Genotyping of Mycobacterium Intracellulare

目的分析我国胞内分枝杆菌临床分离株的耐药谱及基因型特征,为治疗胞内分枝杆菌感染性疾病提供科学依据。方法纳入2013-2015年北京胸科医院150株胞内分枝杆菌临床分离株,采用微孔板Alamar Blue法测定胞内分枝杆菌对15种药物的最低抑菌浓度(MIC),以确定其药物的敏感度;对16个可变数目串联重复序列(VNTR)位点进行PCR扩增和产物电泳分析,使用BioNumerics软件对菌株进行聚类分析,以确定其基因型特征。使用SPSS19.0软件对结果进行统计分析,应用Х^2检验分析不同组间耐药率的差别。结果药敏试验结果显示,克拉霉素(97.3%,146/150)、莫西沙星(94.0%,141/150)和阿米卡星(90.0%,135/150)对胞内分枝杆菌具有较好的抗菌活性;75.3%(113/150)、64.0%(96/150)、52.7%(79/150)和8.7%(13/150)的菌株对利福平、利奈哩胺、卷曲霉素和乙胺丁醇敏感;3种注射类抗结核药物的MIC50与MIC90值为:阿米卡星4和16mg/L,链霉素4和16mg/L,卷曲霉素8和16mg/L;5种氟座诺酮类药物的MIC50与MIC90值为:莫西沙星0.5和2mg/L,环丙沙星1和8mg/L,左氧氟沙星1和8mg/L,安妥沙星2和16mg/L,氧氟沙星2和16mg/L。采用16位点VNTR方法对胞内分枝杆菌进行基因分型,150株胞内分枝杆菌共分为21个簇,121种基因型,总Hunter-Gaston指数为0.997。结论克拉霉素、莫西沙星和阿米卡星在体外对胞内分枝杆菌具有较好的抗菌活性;16位点VNTR方法对胞内分枝杆菌临床分离株的分辨率较高;胞内分枝杆菌的耐药谱与菌株是否成簇并无明显相关性。

Objective To investigate the antimicrobial susceptibility and genotyping of Mycobacterium intracellulare.Methods A total of 150 M.intracellulare isolates were coIlected.The susceptibility against 15 antimicrobial agents widely used for treatment of non-tuberculosis mycobacteria(NTM)infections,was tested by broth microdilution assay.Variable number of tandem repeats(VNTR)assay was also performed using the 16-loci genotyping method.Results The drug susceptibility test revealed that clarithromycin(97.3%,146/150),moxifloxacin(94.0%,141/150)and amikacin(90.0%,135/150)had the best antimicrobial activities in vitro against the M.intracellulare isolates.Secondly,75.3%(113/150),64.0%(96/150),52.7%(79/150)and 8.7%(13/150)of the strains were susceptible to rifampicin,linezolid,capreomycin,and ethambutol,respectively.The MIC50 and MIC90 values of the 3 injectable anti-tuberculosis drugs were as follows:amikacin 4 mg/L and 16 mg/L,streptomycin 4 mg/L and 16 mg/L,capreomycin 8 mg/L and 16 mg/L.The MIC50 and MIC90 values of the 5 different fluoroquinolones were 0.5 mg/L and 2 mg/L for moxifloxacin,1 mg/L and 8 mg/L for ciprofloxacin,1 mg/L and 8ug/ml for levofloxacin,2 mg/L and 16 mg/L for antoflolxacin,2 mg/L and 16mg/L for ofloxacin.The Hunter-Gaston Discriminatory Index(HGDI)value for the 16-loci VNTR typing of M.intracellulare isolates was 0.994.VNTR differentiated the 150 isolates into 21 clusters and acquired a total of 121 unique patterns.Drug resistance profile was not independently associated with cluster strains.Conclusions Clarithromycin,moxifloxacin and amikacin had the best antimicrobial activities in vitro against M.intracellulare isolates.The 16-loci VNTR typing revealed a highly discriminatory power and drug resistance profile was not independently associated with cluster strains.