氯法齐明（Cfz）在耐多药结核病短程化疗中发挥重要作用，但结核分枝杆菌（Mtb）对Cfz的耐药机制仍不清楚。前期研究对比分析了16株Cfz耐药株和16株Cfz敏感株的全基因组序列，发现ndh突变可能与Cfz耐药相关，之后的临床菌株验证和ndh G301D定点诱变结果也支持该推论。Cfz可被ndh编码的Ⅱ型 NADH：甲基萘醌氧化还原酶（NDH-2）还原，之后自发氧化过程中产生的活性氧类（ROS）可杀灭Mtb。研究假设为ndh突变导致NDH-2酶活性改变影响Cfz还原，改变ROS产量，从而致Mtb对Cfz耐药。本研究拟通过大样本验证耐药基因的临床相关性、应用定点诱变和回复突变试验研究ndh突变对Cfz耐药的影响、通过测定突变NDH-2酶活性变化确定ndh突变对ROS产量的影响、评估ndh突变对Mtb适应度代价的影响，从而阐明ndh突变致Mtb对Cfz耐药的分子机制，便于及时诊断Cfz耐药。

Clofazimine (Cfz) might shorten multiple drug resistant tuberculosis regimen, but the mechanisms associated with Cfz resistance of mycobacterium tuberculosis (Mtb) are not well characterized. To understand the mechanisms, 16 Cfz-resistant and 16 Cfz-susceptible Mtb were subjected to whole genome sequencing to identify Cfz resistance associated genes, which were then experimentally confirmed using further clinical isolates and site-directed mutagenesis. The results indicated the association between ndh gene mutation and Cfz resistance. Type II NADH: menaquinone oxidoreductase (NDH-2), which coded by ndh gene, could reduce Cfz and nonenzymatic oxidation of reduced Cfz by O2 yielding CFZ and reactive oxygen species (ROS). High levels of intracellular ROS could be bactericidal. The hypothesis is that resistance to Cfz can be mediated by mutations in ndh gene, which could alter the activity of NDH-2 and would affect the reduction of Cfz and yields of ROS. To address the hypothesis, the association between ndh mutation and Cfz resistance will be confirmed using lots of clinical isolates and site-directed mutagenesis and complementary assay. The activity of the mutant variants of NDH-2 and the yields of ROS will be measured. The effects of ndh mutation on the bacterium fitness will be assessed, including growh temperature, growth rates, competing for growth, and drug susceptibility. Our work will identify the molecular mechanism associated with clofazimine resistance of mycobacterium tuberculosis caused by mutation of ndh gene. Our finding will provide useful information for rapid detection of Cfz resistance.