Dynamic Bacterial Resistance: New DTU Study Reveals How Environmental pH and Temperature Alter Antibiotic Efficacy

New DTU research shows that bacteria can switch between resistant and susceptible states depending on environmental pH and temperature, impacting treatment success.

By: AXL Media

Published: Mar 10, 2026, 12:28 PM EDT

Source: Lene Hundborg Koss

Challenging the Static Nature of Laboratory Resistance Tests

For decades, clinicians and veterinarians have relied on standardized laboratory assays to determine whether a bacterial infection is susceptible to antibiotic treatment. While these tests provide a necessary baseline for comparing results across global laboratories, new research from the Technical University of Denmark (DTU) suggests they may not tell the full story. The study reveals that the performance of resistance genes can fluctuate dramatically depending on the specific environmental conditions, such as acidity or heat, that a bacterium encounters within a living host.

The Impact of pH and Temperature on Gene Function

The DTU team, led by Professor Frank Møller Aarestrup, investigated two widespread resistance genes—CTX-M-15 and CMY-2—to see how they responded to environmental changes. They discovered that factors like pH and temperature act as a "dimmer switch" for these genes. For instance, the CTX-M-15 gene provided the strongest defense in acidic environments but became markedly weaker as conditions became more alkaline. This suggests that a treatment might fail in one part of the body while succeeding in another, despite identical laboratory results.

Avian versus Human Physiological Environments

One of the most significant findings involved the difference in body temperatures between species. The researchers observed distinct changes in resistance levels when comparing a human's 37°C to a bird's 42°C. If a resistance gene functions more efficiently at the higher temperature of a bird, that species may become a more effective "reservoir" for that specific type of resistant bacteria. Understanding these niche preferences is crucial for tracking how antimicrobial resistance (AMR) spreads through the environment, agriculture, and urban areas over long distances.