浙江省结核分枝杆菌临床分离株gyrA基因突变与氧氟沙星耐药的相关性

Correlation of mutation patterns in gyrA gene in Mycobacterium tuberculosis isolates with ofloxacin resistance

目的分析浙江省结核杆菌临床分离株gyrA基因喹诺酮耐药决定区(QRDR)突变与氧氟沙星耐药的相关性。方法鉴定392株结核杆菌临床菌株并检测对利福平、异烟肼、链霉素、乙胺丁醇及氧氟沙星的药物敏感性,PCR法分别扩增30株氧氟沙星敏感株和52株氧氟沙星耐药株的gyrA基因片段并测序。结果临床菌株对氧氟沙星耐药率为13.3%(52/392)。39株氧氟沙星耐药株gyrA基因编码的90、91和94位氨基酸存在突变,有31株发生Asp94Gly/Asn/Ala/His/Tyr突变为最常见(59.6%),12株发生Ala90Val/Lys突变,3株发生Ser91Pro/Trp突变(其中Ser91Trp为首次报道),7株存在双突变。有1株敏感株gyrA基因扩增片段中存在Asp94Asn突变。所有测序菌株都存在Ser95Thr突变。结论结核杆菌gyrA基因QRDR突变与氧氟沙星耐药密切相关。

Objective To analyze mutations in the quinolone - resistance - determining - region （QRDR） in gyrA gene and ofloxacin resistance in 392 M. tuberculosis isolates in Zhejiang. Methods Three hundred and ninety - two M. tuberculosis isolates were identified and performed drug sensitivity test to rifampiein（RFP）, isoniazid （INH）, streptomycin （SM）, ethambutol （EMB） and ofloxaein（OFX）, gyrA gene fore 30 ofloxaein - susceptible and 52 ofloxacin - resistance isolates were amplified by PCR and sequenced. Results The resistance rate of the 392 isolates was 13.3% （52/392） to ofloxacin. Thirty - nine of the 52 ofloxacin - resistance isolates had mutation at 90, 91 and/or 94 site of gyrA genes. The most frequent mutation sites found in this study were Asp94Gly/Asn/Ala/His/Tyr （31/52, 59. 6%） and Ala90Val/Lys （ 12/52, 23. 1% ） , and the rest was Ser91Pro/Trp （3/52, 5.8% ）, and Ser91Trp was reported for the first time; Seven isolates were double mutations in gyrA; One ofloxacin susceptible isolate had Asp94Asn mutation in gyrA gene. Ser95Thr mutation was found in noth 30 ofloxacin susceptible and 52 ofloxacin resistance isolates. Conclusion There is close association between mutations of QRDR in gyrA gene and fluoroqunolones ofloxacin - resistant in phenotype for M. tuberculosis.