福建省耐多药结核分枝杆菌对氟喹诺酮类药物表型耐药与gyrA基因突变特征分析

目的 了解福建省耐多药(Multi-drug resistant, MDR)结核分枝杆菌(Mycobacterium tuberculosis, Mtb)氟喹诺酮类药物(Fluoroquinolones,FQs)的gyrA基因突变特征,为FQs耐药菌株的快速分子药敏检测提供基础科学数据。方法 收集来自福建省2010-2011年和2008-2009年耐药监测点的所有MDR Mtb临床菌株,采用常规比例法进行FQs敏感性试验。PCR扩增包含gyrA耐药决定区的基因片段,测序后比对分析。结果 共收集到MDR结核分枝杆菌临床菌株119株,经常规药敏试验,氧氟沙星(Ofloxacin,Ofx)的耐药率为26.89%,左氧氟沙星(Levofloxacin,Lfx)耐药率为25.21%,莫西沙星(Moxifloxacin,Mfx)耐药率为11.76%。FQs敏感株gyrA基因未检测到突变。gyrA基因在Ofx耐药菌株的突变率为84.38%(27/32),Lfx耐药菌株的突变率为83.33%(25/30), Mfx耐药菌株的突变率为92.86%(13/14)。gyrA基因突变为点突变,共发现有5种突变类型,以Asp94Gly,Asp94Asn和Ala90Val为主。结论 福建省MDR-Mtb对FQs耐药的主要原因是gyrA基因突变,最常见的突变位于第94位,第90位和第91位密码子。

Phenotypic fluoroquinolones resistance and characteristics of gyrA mutation in MDR Mycobacterium tuberculosis isolates in Fujian,China

Our study investigated the phenotypic fluonoquinolones resistance and the molecular characteristics of mutation in gyrA in MDR Mycobacterium tuberculosis (Mtb) clinical strains in Fujian Province, and provided some reference for rapid molecular detection of fluonoquinolones resistance in Mtb. MDR isolates collected from drug resistant survey sites through the province in 2010-2011 and 2007-2008, and the strains were conducted FQs susceptibility testing by proportion method. The quinolone resistant determining region (QRDR) in gyrA was amplified by PCR and the PCR products were sequenced, the results of sequencing were blasted with H37Rv. Of 119 strains were collected and performed FQs susceptibility testing. The rate of resistant to FQs was 26.89% (Ofloxacin, Ofx), 25.21% (Levofloxacin, Lfx), and 11.76% (Moxifloxacin, Mfx) respectively. No mutation was found in gyrA in fluonoquinolones sensitive MDR strains. The mutation rate of gyrA in Ofx resistant MDR strains was 84.38% (27/32), the mutation rate of Lfx resistant MDR was 83.33% (25/30), and that of Mfx was 92.86% (13/14). The characteristic of gyrA mutation in our study was point mutation, with five mutation types, and mainly was Asp94Gly, Asp94Asn and Ala90Val. Thus, we conclude that gyrA mutation is the main reason of MDR strains resistant to flunoquinolones in Fujian Province. And the most common mutation is in the codon 94, codon 90, and codon 91.