Short Antibiotic Treatment May Disrupt Gut Health Long-Term: Study

New Delhi: A new study from Stanford University highlights that even short-term antibiotic use can lead to persistent antimicrobial resistance (AMR) in human gut bacteria — a growing global health crisis responsible for millions of deaths each year.

Published in the journal Nature, the study focused on ciprofloxacin, a commonly prescribed antibiotic used to treat various bacterial infections. Researchers discovered that ciprofloxacin could induce resistance in gut bacteria, with effects lasting over 10 weeks — and possibly detectable for up to a year.

While previous research on AMR has largely depended on laboratory settings and animal models, this study is among the first to track resistance evolution in humans over time. The research involved 60 healthy adults, each prescribed 500 mg of ciprofloxacin twice daily for five days.

Using stool samples, scientists applied advanced computational tools to analyze the bacterial DNA. They reconstructed over 5,600 bacterial genomes and identified 2.3 million genetic variants within the gut microbiome.

Significantly, 513 bacterial populations showed mutations in the gyrA gene, which is known to confer resistance to fluoroquinolones — a class of antibiotics that kill bacteria by disrupting DNA replication. The study revealed that about 10% of initially susceptible bacteria developed resistance due to these mutations, which arose independently across individuals and species.

Interestingly, bacterial populations that were more abundant before antibiotic exposure were not only more likely to acquire resistance but also experienced sharp declines during treatment.

“These findings reveal that even a brief course of ciprofloxacin can drive resistance in gut bacteria,” the researchers stated. “The mutations can persist long after the antibiotic is gone, raising concerns about long-term impacts on microbial health and resistance spread.”

The study underscores the human gut's potential to foster antibiotic resistance and identifies both genetic and ecological factors contributing to bacterial adaptation. It also reinforces the need for cautious and appropriate use of antibiotics to curb the global threat of AMR.