How Host Stress May Prime Tuberculosis to Rapidly Gain Drug Resistance
ISB researchers show that oxidative stress generated by the host immune system can prime tuberculosis bacteria to rapidly evolve antibiotic resistance, revealing how resistance may begin before treatment.
Scientists at the Institute for Systems Biology (ISB) have uncovered a mechanism that may help explain how tuberculosis antibiotic resistance rapidly develops — one that begins before treatment even starts.
In a study published in Nature Communications, researchers found that oxidative stress encountered within the host — part of the immune system’s natural response to infection — can prime mycobacteria, including Mycobacterium tuberculosis, to evolve drug resistance more quickly. The findings suggest that the conditions bacteria encounter within the host may shape their evolutionary path long before antibiotics are introduced.
“Our findings suggest that the stressful conditions bacteria encounter inside the host are already shaping their ability to survive antibiotics,” said PhD Candidate Evan Pepper-Tunick, first author of the study. “By the time treatment begins, some populations may already be predisposed to develop resistance.”
Rethinking How Resistance Begins
Antibiotic resistance is often viewed as a direct consequence of drug exposure. But this study suggests that the process may begin much earlier, driven by the biological environment within the host.
When the immune system responds to infection, it produces oxidative stress — a form of chemical pressure intended to kill invading pathogens. The ISB-led team found that this stress can instead act as a selective force, favoring bacterial strains that are better equipped to survive it.
Crucially, the study shows that mutations in bacterial oxidative stress response pathways can create a permissive genomic state, allowing otherwise costly resistance mutations to emerge and persist. These conditions enable high-level resistance to develop more readily — even without the fitness costs that typically limit the emergence of resistant strains.
“This changes how we think about resistance,” said ISB Professor Dr. Nitin Baliga, senior author on the study. “It’s not just about exposure to antibiotics. The host environment itself is helping shape which bacterial populations are most likely to evolve resistance.”
The findings also suggest that sublethal antibiotic exposure — such as incomplete drug penetration — may further accelerate this process when combined with host-induced stress.
Implications for Treatment and Prevention
Tuberculosis remains the world’s deadliest infectious disease, with drug-resistant strains posing a growing global health challenge. According to the World Health Organization, drug-resistant tuberculosis continues to threaten progress in global TB control.
By identifying oxidative stress management as a key factor in resistance evolution, the study points to new potential strategies for intervention — including therapies that target bacterial stress response pathways.
“Understanding how resistance emerges is critical if we want to stay ahead of it,” Pepper-Tunick said. “If we can disrupt the processes that prime bacteria for resistance, we may be able to slow or even prevent its development.”
The research was conducted in collaboration with scientists at Seattle Children’s Research Institute, University of Melbourne, Pham Ngoc Thach Hospital, and the Hospital for Tropical Diseases.
