Chemical disarming of isoniazid resistance in Mycobacterium tuberculosis

Area of Science:

• Microbiology
• Infectious Diseases
• Drug Discovery

Background:

• Mycobacterium tuberculosis (Mtb) causes significant global mortality, with persistent infections exacerbated by antibiotic resistance.
• Drug tolerance and resistance in Mtb are major challenges for tuberculosis (TB) therapy.
• Emergence of multidrug-resistant Mtb strains necessitates novel therapeutic strategies.

Purpose of the Study:

• To identify compounds that inhibit Mtb's stress and drug tolerance mechanisms.
• To investigate the potential of these compounds in overcoming antibiotic resistance.
• To explore the link between Mtb persistence, respiration, and antibiotic sensitivity.

Main Methods:

• Utilized a chemical screening approach targeting Mtb tolerance, not direct killing.
• Identified and characterized the small molecule C10 for its effects on Mtb.
• Conducted mechanistic studies to elucidate C10's mode of action, including its impact on Mtb respiration and isoniazid (INH) resistance.

Main Results:

• C10 was identified as a molecule that blocks tolerance to oxidative stress, acid stress, and isoniazid (INH).
• C10 prevents the selection of INH-resistant Mtb mutants and restores INH sensitivity in resistant strains with katG mutations.
• Mechanistic studies revealed that C10 inhibits Mtb respiration, linking respiration to INH sensitivity.

Conclusions:

• The small molecule C10 represents a promising therapeutic lead for combating Mtb drug tolerance and resistance.
• INH resistance in Mtb is not absolute and can be reversed, offering new avenues for TB treatment.
• Targeting Mtb respiration may be a viable strategy to enhance the efficacy of existing TB drugs.