Host oxidative stress primes mycobacteria for rapid antibiotic resistance evolution

Journal article

The rapid emergence of multidrug-resistant Mycobacterium tuberculosis (Mtb) threatens global tuberculosis (TB) control, yet the mechanisms enabling rapid evolution of resistance in Mtb remain poorly understood. Here, we show that pre-existing mutations in oxidative stress response genes create permissive genomic backgrounds that accelerate high-level isoniazid resistance (INHR), challenging the paradigm that resistance mutations must precede compensatory adaptation. Using Mycobacterium smegmatis mc2155 (Msm) as a model, we demonstrate that brief exposure to sublethal isoniazid (INH) enriches for “low-level resistance and tolerance” (LLRT) mutants in a single step. LLRT mutants, particularly those with ohrR loss-of-function mutations, acquire high-level resistance (>500× IC50) at ~6-fold higher rates than wildtype, primarily through otherwise deleterious mycothiol biosynthesis mutations that become tolerable in an oxidative stress-buffered background. Crucially, sublethal oxidative stress alone, mimicking host immune pressure, nearly tripled the rate of INHR evolution. Analysis of 1578 clinical Mtb isolates revealed significant enrichment of oxidative stress-related loci among those associated with INHR. Reanalysis of genome-wide CRISPRi data further linked oxidative stress response pathways to survival under multiple antibiotics. Together, these findings suggest that host-imposed oxidative stress and suboptimal drug exposure may prime Mtb populations for rapid resistance evolution, highlighting oxidative stress defenses as potential targets to limit resistance emergence.

Authors: Pepper-Tunick, E; Srinivas, V; Mast, FD; Li, S; Russ, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature Communications
• Volume: 17
• Issue: 1
• Article number: 4106
• Publication date: 2026-05-07
• Acceptance date: 2026-04-16
• DOI: 10.1038/s41467-026-72496-4
• EISSN: 2041-1723
• ISSN: 2041-1723
• Language: English