01.10.2025
Antibiotic resistance can also make bacteria more vulnerable
Antibiotic resistance is one of the greatest challenges in modern medicine. A new study now shows that Haemophilus influenzae can rapidly adapt to commonly used beta-lactam antibiotics. However, the genetic changes and their consequences are surprisingly diverse and difficult to predict. Some mutations even make the bacteria more susceptible to other drugs.
Haemophilus influenzae can cause severe diseases such as pneumonia, sepsis, or meningitis in young children, the elderly, and people with weakened immune systems. The current outbreak in Hamburg, which has already claimed several lives, highlights how dangerous this pathogen can be. Normally, infections caused by H. influenzae can be treated with beta-lactam antibiotics that specifically target the bacterial cell wall. But resistance is rapidly evolving, rendering established treatments ineffective.
Researchers at the Research Center Borstel (Leibniz Lung Center) and Kiel University (Kiel Evolution Center) have now investigated how quickly H. influenzae adapts to antibiotics and what surprising side effects this resistance evolution can have. The results have now been published in the journal Antimicrobial Agents and Chemotherapy.
“Our results show that resistance evolution does not always follow the same pattern. Even small genetic differences can have very different effects on how well antibiotics work. Particularly surprising was that some beta-lactam-resistant strains simultaneously became more susceptible to other drug classes,” says Sabine Petersen, first author of the study.
“If we understand which mutations make bacteria more vulnerable, this opens up new opportunities for treating infections,” adds Prof. Matthias Merker. “In the long run, this knowledge could help us slow down resistance development.”
The study highlights that the evolution of antibiotic resistance is more complex than expected and that understanding it is crucial to keeping existing therapies effective in the future.
Publication: Petersen S, Diricks M, Utpatel C, Schulenburg H, Merker M.0.Evolution of beta-lactam resistance causes fitness reductions and several cases of collateral sensitivities in the human pathogen Haemophilus influenzae. Antimicrob Agents Chemother0:e00576-25.https://doi.org/10.1128/aac.00576-25
