Walter Nicholas D, Dolganov Gregory M, Garcia Benjamin J, Worodria William, Andama Alfred, Musisi Emmanuel, Ayakaka Irene, Van Tran T, Voskuil Martin I, de Jong Bouke C, Davidson Rebecca M, Fingerlin Tasha E, Kechris Katerina, Palmer Claire, Nahid Payam, Daley Charles L, Geraci Mark, Huang Laurence, Cattamanchi Adithya, Strong Michael, Schoolnik Gary K, Davis John Lucian
Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora Pulmonary Division, Denver Veterans Administration Medical Center, Colorado.
Department of Microbiology and Immunology, Stanford University, California.
J Infect Dis. 2015 Sep 15;212(6):990-8. doi: 10.1093/infdis/jiv149. Epub 2015 Mar 11.
Treatment initiation rapidly kills most drug-susceptible Mycobacterium tuberculosis, but a bacterial subpopulation tolerates prolonged drug exposure. We evaluated drug-tolerant bacilli in human sputum by comparing messenger RNA (mRNA) expression of drug-tolerant bacilli that survive the early bactericidal phase with treatment-naive bacilli.
M. tuberculosis gene expression was quantified via reverse-transcription polymerase chain reaction in serial sputa from 17 Ugandans treated for drug-susceptible pulmonary tuberculosis.
Within 4 days, bacterial mRNA abundance declined >98%, indicating rapid killing. Thereafter, the rate of decline slowed >94%, indicating drug tolerance. After 14 days, 16S ribosomal RNA transcripts/genome declined 96%, indicating slow growth. Drug-tolerant bacilli displayed marked downregulation of genes associated with growth, metabolism, and lipid synthesis and upregulation in stress responses and key regulatory categories-including stress-associated sigma factors, transcription factors, and toxin-antitoxin genes. Drug efflux pumps were upregulated. The isoniazid stress signature was induced by initial drug exposure, then disappeared after 4 days.
Transcriptional patterns suggest that drug-tolerant bacilli in sputum are in a slow-growing, metabolically and synthetically downregulated state. Absence of the isoniazid stress signature in drug-tolerant bacilli indicates that physiological state influences drug responsiveness in vivo. These results identify novel drug targets that should aid in development of novel shorter tuberculosis treatment regimens.
治疗开始后能迅速杀死大多数药物敏感的结核分枝杆菌，但有一小部分细菌亚群能耐受长时间的药物暴露。我们通过比较在杀菌早期存活下来的耐药物杆菌与未接受过治疗的杆菌的信使核糖核酸（mRNA）表达，评估了人类痰液中的耐药物杆菌。
通过逆转录聚合酶链反应对17名接受药物敏感型肺结核治疗的乌干达人的系列痰液中的结核分枝杆菌基因表达进行定量分析。
在4天内，细菌mRNA丰度下降超过98%，表明细菌被迅速杀灭。此后，下降速率减缓超过94%，表明出现了药物耐受性。14天后，16S核糖体RNA转录本/基因组下降了96%，表明生长缓慢。耐药物杆菌显示出与生长、代谢和脂质合成相关的基因显著下调，而在应激反应和关键调控类别中上调，包括与应激相关的西格玛因子、转录因子和毒素-抗毒素基因。药物外排泵上调。异烟肼应激特征在最初药物暴露时被诱导，然后在4天后消失。
转录模式表明，痰液中的耐药物杆菌处于生长缓慢、代谢和合成下调的状态。耐药物杆菌中异烟肼应激特征的缺失表明生理状态会影响体内的药物反应性。这些结果确定了新的药物靶点，应有助于开发新的更短疗程的结核病治疗方案。
