Short-Term Antibiotic Use Can Trigger Long-Lasting Resistance in Gut Microbes

Recent research from Stanford University highlights the concerning impact of short-term antibiotic treatments on the development of persistent resistance in human gut bacteria. The study focused on ciprofloxacin, a commonly used antibiotic, administered at 500 mg twice daily for five days to healthy adults. Over a period of 20 weeks, participants collected multiple stool samples, which were analyzed through comprehensive shotgun metagenomic sequencing. This approach uncovered significant genetic changes within the gut microbiome, particularly in bacteria harboring mutations in the gyrA gene, a key player in fluoroquinolone resistance.

The findings revealed that resistance mutations emerged independently across diverse bacterial species within the gut, often in populations that were initially abundant and experienced declines during treatment. Notably, once these resistant strains appeared, they persisted for more than 10 weeks, with predictions indicating their presence could last up to a year. Interestingly, these mutations did not impose any evident fitness costs, allowing resistant bacteria to remain dominant even after antibiotic treatment ceased.

This study emphasizes that even brief antibiotic courses can lead to durable resistance, as resistant bacteria can evolve in the gut microbiota without prior infection or significant health impacts. Since these resistance traits can potentially transfer to pathogenic bacteria via horizontal gene transfer, the implications for public health are substantial. The research underscores the necessity for more precise antibiotic stewardship and monitoring of microbial composition to mitigate long-term resistance risks. Ultimately, these insights suggest that understanding the initial microbial landscape could help predict and manage resistance outcomes more effectively.

This research adds a crucial piece to the puzzle of antimicrobial resistance, advocating for cautious and informed antibiotic use to prevent the silent, yet enduring, evolution of resistant gut bacteria.

Source: https://medicalxpress.com/news/2025-04-short-term-antibiotic-linked-resistance.html