Profiling persistent tubercule bacilli from patient sputa during therapy predicts early drug efficacy

Area of Science:

• Microbiology
• Genomics
• Infectious Diseases

Background:

• Tuberculosis (TB) remains a major global health threat, necessitating improved treatment strategies.
• Identifying persistent Mycobacterium tuberculosis (M.tb) bacilli and predictive biomarkers is crucial for effective drug development.
• Current TB treatment success rates, while high, still leave room for improvement.

Purpose of the Study:

• To map the mRNA signatures of M.tb in patient sputum during early drug therapy.
• To identify transcriptional signatures that predict treatment efficacy.
• To characterize the phenotypic state of M.tb bacilli persisting through therapy.

Main Methods:

• Genome-wide transcriptional profiling of M.tb from sputum samples of 15 patients.
• Analysis of mRNA signatures at baseline and at 3, 7, and 14 days post-treatment initiation.
• Correlation of bacterial gene expression patterns with clinical and microbiological parameters of disease severity.

Main Results:

• Early (3-day) mRNA profiles indicated drug activity, while later (7- and 14-day) profiles showed reduced M.tb metabolic activity.
• A drug-tolerant M.tb population appears to dominate sputum, with early treatment killing a drug-sensitive sub-population.
• Identified transcriptional signatures that accurately predicted early treatment success measures, including bacterial load decline and TB test positivity.

Conclusions:

• Defined the transcriptional signature of M.tb persisting in sputum after two weeks of therapy.
• Demonstrated that bacterial sputum signatures reflect clinical disease variability.
• Showed that dynamic M.tb mRNA profiles during early chemotherapy predict treatment efficacy weeks later, advocating for their use as biomarkers.