Starvation State Enables Staph aureus Survival Despite DNA Repair Loss, Challenging Antibiotic Strategies

Jonathan Batchelder, PhD, research associate, University of Connecticut Health Center, highlighted his work that demonstrated how Staphylococcus aureus adapts to survive fluoroquinolone treatment under conditions that mimic real-world infections. His study focused on the role of RecA, a protein central to repairing double-stranded DNA breaks—damage typically induced by fluoroquinolone antibiotics. While RecA has long been considered essential for bacterial survival following such damage, the findings suggest that S aureus may rely on additional, previously underappreciated pathways.

Under nutrient-limited, or “starvation,” conditions—common in host environments during infection—the bacteria demonstrated a surprising resilience. Even when RecA was absent, S aureus retained a significant survival advantage after antibiotic exposure. This challenges long-standing assumptions about how bacterial DNA repair mechanisms dictate treatment outcomes and raises important questions about how infections persist despite therapy.

“RecA is a very important DNA repair protein…when you treat bacteria with fluoroquinolones, those are the kind of breaks that you get,” Batchelder said. “But what we found was that even in this starvation state…loss of recA makes the cells not able to survive nearly as well—yet they still retain some survival advantage.”

Further investigation revealed that this survival benefit was not solely dependent on traditional DNA repair pathways. Even when researchers disrupted additional repair-related proteins, such as RexB, the bacteria continued to persist under starvation conditions. This indicates that S aureus may be leveraging alternative mechanisms—potentially including reduced drug-target interactions or enhanced drug efflux—to withstand antibiotic stress.

From a clinical perspective, these findings complicate the development of adjunctive therapies aimed at boosting antibiotic efficacy. Strategies that target RecA, for example, may not be sufficient in nutrient-limited environments where alternative survival pathways are active.

“What these data are suggesting is that if the cells are starving…even if you were to use one of these RecA inhibitors, it probably wouldn’t do much good,” Batchelder said. “It seems that in these conditions, Staph has an alternative way of surviving.”

The research also opens the door to new therapeutic approaches. One possibility is designing drugs with stronger binding affinity to bacterial topoisomerases, preventing dissociation during starvation. Another avenue involves targeting efflux pumps, which may play a role not only during treatment but also in the post-treatment period when bacteria could be expelling residual antibiotic.

Ultimately, the study underscores a broader lesson in infectious disease research: bacterial behavior can vary significantly between species and environmental contexts. While Escherichia coli has long served as a model organism, these findings highlight the need to study pathogens like S aureus in conditions that closely reflect human infections.

As researchers continue to explore these alternative survival pathways, the work may inform more effective strategies to combat persistent infections and reduce antibiotic resistance.

Reference
Batchelder J. et al. Deciphering the Timing of DNA Repair to Sensitize Staphylococcus aureus to Fluoroquinolones.Presented at ASM Microbe 2025. June 2025. Los Angeles, CA.