Fujiwara Mamoru, Kawasaki Masanori, Hariguchi Norimitsu, Liu Yongge, Matsumoto Makoto
Department of Medical Innovations, New Drug Research Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan.
TB Projects, Otsuka Pharmaceutical Co., Ltd, Tokyo, Japan.
Tuberculosis (Edinb). 2018 Jan;108:186-194. doi: 10.1016/j.tube.2017.12.006. Epub 2017 Dec 30.
Delamanid, a bicyclic nitroimidazooxazole, is effective against M. tuberculosis. Previous studies have shown that resistance to a bicyclic nitroimidazooxazine, PA-824, is caused by mutations in an F-dependent bio-activation pathway. We investigated whether the same mechanisms are responsible for resistance to delamanid. Spontaneous resistance frequencies were determined using M. bovis BCG Tokyo (BCG) and M. tuberculosis H37Rv. F high-performance liquid chromatography (HPLC) elution patterns of homogenates of delamanid-resistant BCG colonies and two previously identified delamanid-resistant M. tuberculosis clinical isolates were examined, followed by sequencing of genes in the F-dependent bio-activation pathway. Spontaneous resistance frequencies to delamanid were similar to those of isoniazid and PA-824. Four distinct F HPLC elution patterns were observed, corresponding to colonies with mutations on fgd1, fbiA, fbiB, and fbiC with no change in the ddn mutants from the wildtype. Complementation with the wildtype sequence of the mutated gene restored susceptibility. The two delamanid-resistant clinical isolates had ddn mutations and the wildtype F HPLC elution pattern. In conclusion, delamanid-resistant bacilli have mutations in one of the 5 genes in the F-dependent bio-activation pathway with distinct F HPLC elution patterns. Both genetic and phenotypic changes may be considered in the development of a rapid susceptibility test for delamanid.
地拉曼德是一种双环硝基咪唑并恶唑，对结核分枝杆菌有效。先前的研究表明，对双环硝基咪唑并恶嗪PA-824的耐药性是由F依赖性生物激活途径中的突变引起的。我们研究了对 地拉曼德 的耐药性是否由相同机制导致。使用卡介苗东京株（BCG）和结核分枝杆菌H37Rv测定自发耐药频率。检测了耐地拉曼德BCG菌落匀浆以及两个先前鉴定的耐地拉曼德结核分枝杆菌临床分离株的F高效液相色谱（HPLC）洗脱模式，随后对F依赖性生物激活途径中的基因进行测序。对地拉曼德的自发耐药频率与异烟肼和PA-824相似。观察到四种不同的F HPLC洗脱模式，分别对应于fgd1、fbiA、fbiB和fbiC发生突变的菌落，而ddn突变体与野生型相比无变化。用突变基因的野生型序列进行互补可恢复敏感性。这两个耐地拉曼德临床分离株有ddn突变和野生型F HPLC洗脱模式。总之，耐地拉曼德的杆菌在F依赖性生物激活途径的5个基因之一中发生突变，具有不同的F HPLC洗脱模式。在开发地拉曼德快速药敏试验时，可能需要考虑遗传和表型变化。
