耐药结核分枝杆菌基因突变分析

目的 探讨结核分枝杆菌耐药表型与基因突变位点之间的相互关系.方法 采用序列特异性引物分别扩增92株结核分枝杆菌利福平耐药基因rpoB,异烟肼耐药基因katG、inhA、ahpC,链霉素耐药基因rrs、rpsL,乙胺丁醇耐药基因embB及喹诺酮耐药基因gyrA,SSCP筛选出突变序列,DNA测序分析突变性质.结果 59株利福平耐药株rpoB基因突变检出率94.9%(56/59),以Ser450Trp突变最多;90株异烟肼耐药株中,katG基因突变检出率38.9%(35/90),以Ser315Thr最多,3株检出inhA基因突变,ahpC基因无突变检出;34株喹诺酮耐药株中gyrA基因突变检出率82.4%(28/34),主要为Asp94Gly,其次为Ala90Val;31株链霉素耐药株中,15株检出rrs突变,最常见为A514C和A1041G,10株发生rpsL Lys88Arg突变,总的链霉素基因突变检出率为77.4%(24/31);31株乙胺丁醇耐药株中embB 基因突变检出率19.4%(6/31),主要为Met306Val.结论 耐药结核分枝杆菌耐药情况较为严重,以DNA测序为基础的基因突变分析能快速有效地检测结核分枝杆菌的rpoB、katG、gyrA、rrs、rpsL、embB 等耐药分子标识,显示了西安地区耐药性结核分枝杆菌的突变特点,为结核病的临床诊断和合理用药提供了实验依据.

Gene mutations analysis in resistant Mycobacterium tuberculosis isolates

Objective To investigate the relationship between the phenotypes and the patterns of genetic mutations in the corresponding resistance genes (rpoB, katG, inhA, ahpC, rrs, rpsL, embB and gyrA) in resistant Mycobacterium tuberculosis (MTB) isolates. Methods Rifampicin-resistant gene (rpoB), isoniazid-resistant genes (katG, inhA, ahpC), streptomycin-resistant genes (rrs, rpsL), ethambutol-resistant gene (embB) and quinolinone-resistant gene (gyrA) were amplified by PCR with sequence-specific primers, then mutants screened by single-stranded conformation polymorphism (SSCP) were sequenced. Results rpoB mutation with predominant Ser450Trp pattern was 94. 9% (56/59) in 59 rifampicin-resistant isolates;katG mutation rate was 38. 9% (35/90) and the main pattern was Ser315Thr, but only 3 inhA mutants and no ahpC mutation were determined in 90 isoniazid-resistant isolates;gyrA mutation with main Asp94Gly then Ala90Val pattern was 82.4% (28/34) in 34 quinolinone-resistant isolates;the total mutation rate was 77.4% in 31 streptomycin-resistant isolates, of which 15 isolates mutated in rrs with main pattern A514C or A1041G, 10 isolates mutated in rpsL Lys88Arg;and embB mutation with main Met306Val accounted for 19.4% (6/31) in 31 ethambutol-resistant isolates. Conclusions The results showed that resistance of resistant MTB may be complicated, and DNA sequencing-based mutation analysis could efficiently detect the molecular makers such as rpoB, katG, gyrA, rrs, rpsL and embB in resistant MTB isolates. Meanwhile, it is notable that the rpoB mutation pattern in our isolates is different from previous report, further effort are needed to confirm the characteristics. The spectrum of potential resistance-related mutations in MTB clinical isolates may lay substantial foundation for the rapid molecular diagnosis and rational use of drug to MTB patients.