浙江地区耐多药结核分枝杆菌基因突变特征分析

Analysis for characteristics of genetic mutations among multi-drug resistant Mycobacterium tuberculosis (MDR-TB) isolates from Zhejiang Province

目的分析浙江地区耐多药结核分枝杆菌(M.tuberculosis complex, MTBC)异烟肼(isoniazid, INH)和利福平(rifampicin, RIF)耐药相关基因突变特征。方法对患者痰标本阳性培养物进行菌种鉴定,提取耐多药菌株DNA,应用PCR法对inhA、katG和rpoB RRDR区进行扩增,并将扩增产物直接进行基因测序。结果共鉴定出3 317株MTBC,对应的患者中初治为3 009例,复治为308例,耐多药结核病(multidrug-resistant tuberculosis, MDR-TB)为84例,占比为2.53%(84/3 317)。其中,在INH耐药方面,47株分别在katG(315)或inhA(-15/-8)发生单位点突变,19株同时出现katG(315)和inhA(-15/-8)突变,18株未检测出上述基因突变,基因型同表型的符合率为78.57%(66/84),突变频率最高的位点是Ser315Thr,占47.62%(40/84)。在RIF耐药方面,79株在rpoB(511、512、513、516、522、526和531位点)出现突变,2株同时出现511/513和511/516突变,突变频率最高的位点是Ser531Leu,占58.33%(49/84),3株未检测出rpoB突变,基因型同表型的符合率为96.43%(81/84)。结论浙江地区MDR-TB流行株基因突变仍然集中在常见的基因位点,表明在本地区利用Xpert MTB/RIF筛查MDR-TB患者仍具有较高的应用价值。

Objective To analyze the characteristics of genetic mutations associated with isoniazid(INH) and rifampicin(RIF)-resistant Mycobacterium tuberculosis(MDR-TB) isolates. Methods Culture positive sputum specimens from suspicious TB were subjected to species identification. Genomic DNAs of Mycobacterium tuberculosis complex(MTBC) were extracted. InhA, katG, and Rifampicin Resistance Determining Region(RRDR) of rpoB gene were amplified. Amplicons were performed with Sanger sequencing. Results A total of 3 317 TB were identified, including3 009 new treated, 308 retreated, and 84 MDR-TB, accounting for 2.53%(84/3 317). In INH resistant isolates, 47 had single-point mutation in katG(315 site) or inhA(-15 or-8 site), and 19 had both katG and inhA mutations. The coincidence rate of genotype with phenotype was 78.57%(66/84). The most frequent mutation was Ser315 Thr(47.62%, 40/84). In RIF resistant isolates, 79 had mutations in rpoB(sites 511, 512, 513, 516, 522, 526 and 531), and 2 had mutations in 511/513 or 511/516. The most frequent mutation was Ser531 Leu(58.33%, 49/84). The coincidence rate of genotype with phenotype was 96.43%(81/84). Conclusions Genetic mutations of inhA, katG and rpoB gene in Zhejiang are concentrated relatively on common gene sites, and Xpert MTB/RIF is still of high application value to screen MDR-TB in Zhejiang.