华东地区耐药结核分枝杆菌katG基因的变异

The investigation of the variability of katG gene in Mycobacterium tuberculosis

目的了解我国华东地区结核分枝杆菌中与异烟肼耐药相关的katG基因的变异情况,提供我国异烟肼耐药相关的基因谱。方法对429株结核杆菌行核酸抽提后先以限制性酶切片段多态性方法检测有无最常见的耐药相关S315T突变,对未发现S315T突变的异烟肼耐药株取部分行katG全基因测序以了解其他位点的变异情况。结果耐药结核分枝杆菌中76．9％(166/216)存在katG基因S315T突变。发现有2株异烟肼高度耐药株中存在katG基因片段的缺失。48株异烟肼耐药株测序结果发现katG基因突变特点如下：突变率较高的有315、463、234位点,其余突变位点较多而分散。315位密码子的突变中除S315T外,S315N突变形式也较常见,占8．7％。结论结核分枝杆菌耐药机制复杂,了解耐药相关基因的变异情况是建立可靠的耐药性分子检测方法的基础。

Objective To investigate the variability of katG gene in Mycobacterium tuberculosis strains isolated in China, and screen the new isoniazid resistance related mutation sites meanwhile. Methods 429 clinical Mycobacterium tuberculosis isolates were included in our research. PCR-RFLP method was applied to screen for the S315T mutation firstly. Whole katG gene sequencing was done in those resistant strains without S315T mutation to explore the unknown mutated sites associated with isoniazid resistance. Results S315 mutation were found in 76. 9%（166/216）resistant stains. Complete or part deletion of katG gene was detected in 2 highly-resistant isolates. Sequencing in 48 resistant strains showed that 315, 463 and 234 sites were the most frequent mutation sites, other sites were also found but distributed dispersedly with low prevalence rate as less than 5 %. Besides S315T, S315N were also common in China （8.70/00）. The most common variation is still site mutation. Conclusions The results from the study of genotypes associated with most common clinical resistant phe notypes can be helpful to develop new methods to detect the resistant M. tuberculosis.