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J Infect Dis. 2015 Sep 15;212(6):990-8. doi: 10.1093/infdis/jiv149. Epub 2015 Mar 11.

Transcriptional Adaptation of Drug-tolerant Mycobacterium tuberculosis During Treatment of Human Tuberculosis.

Author information

1
Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora Pulmonary Division, Denver Veterans Administration Medical Center, Colorado.
2
Department of Microbiology and Immunology, Stanford University, California.
3
Integrated Center for Genes, Environment, and Health, National Jewish Health, Denver Computational Bioscience Program, University of Colorado Denver, Aurora.
4
Makerere University-University of California, San Francisco Research Collaboration, Kampala, Uganda.
5
Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora.
6
Institute of Tropical Medicine, Antwerp, Belgium.
7
Integrated Center for Genes, Environment, and Health, National Jewish Health, Denver.
8
Department of Epidemiology and Biostatistics Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora.
9
Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora.
10
Division of Pulmonary and Critical Care Medicine, University of California San Francisco.
11
Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora Division of Mycobacterial and Respiratory Infections, National Jewish Health, Denver, Colorado.
12
Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora.
13
Division of Pulmonary and Critical Care Medicine, University of California San Francisco HIV/AIDS Division, University of California San Francisco.

Abstract

BACKGROUND:

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.

METHODS:

M. tuberculosis gene expression was quantified via reverse-transcription polymerase chain reaction in serial sputa from 17 Ugandans treated for drug-susceptible pulmonary tuberculosis.

RESULTS:

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.

CONCLUSIONS:

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.

KEYWORDS:

Mycobacterium tuberculosis/genetics; Mycobacterium tuberculosis/physiology; gene expression profiling; pulmonary/epidemiology; sputum/microbiology; tuberculosis

PMID:
25762787
PMCID:
PMC4548467
DOI:
10.1093/infdis/jiv149
[Indexed for MEDLINE]
Free PMC Article

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