Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a major global

health challenge, exacerbated by lengthy treatment regimens and rising drug resistance.

While genetic resistance mechanisms have been well-characterized, non-genetic factors,

such as those arising from cell state, are poorly understood. This thesis investigates how

the metabolic state of Mtb influences its susceptibility to key anti-tubercular drugs, highlighting

a metabolic adaptive response to antibiotics driven by carbon source availability.

Through in vitro susceptibility testing in different carbon environments, this work identified

the presence of pyruvate can result in transient, non-hereditable isoniazid resistance

in Mtb.

Metabolic flux analysis revealed that pyruvate drives elevated flux through the pentose

phosphate pathway to induce antibiotic resistance to isoniazid. Through a combination

of redox state profiling, lipidomics and susceptibility testing, it was found that this flux

induces a reductive cellular state that may be linked to restoration of cell wall biogenesis.

Interestingly, it was also found that this flux does not result in cross-resistance to other

mycolic acid wall synthesis inhibitors, highlighting that isoniazid likely exerts additional

effects outside of its canonical mode of action.

Leveraging these insights, this thesis also explores the development of novel adjuvant

therapies designed to depress flux through the pentose phosphate pathway and enhance

antibiotic potency. I have identified compounds that, when co-administered with isoniazid,

will significantly improve bacterial killing to result in complete clearance of Mtb after

4 weeks treatment. These findings underscore the therapeutic potential of metabolic

adjuvants as a strategy to improve antibiotic efficacy and shorten treatment duration.

Collectively, this research advances our understanding of Mtb physiology and opens new avenues for pathogen-directed adjunctive therapies.