Escherichia coli extract (OM-89) preserves gut microbial balance more effectively than antibiotics in a healthy mouse model

Abstract

Urinary tract infections (UTIs) are among the most common infectious diseases globally, with a recurrence rate of approximately 20-30% in patients. Traditionally, preventing recurrent UTIs (rUTIs) often involves the prolonged use of low-dose antibiotics. However, these approaches can lead to gut dysbiosis, a condition associated with various adverse effects and potentially contributing to rUTIs. OM-89 is a non-antibiotic option for preventing rUTIs, but its impact on the gut microbiota is poorly understood. This study compared the effects of OM-89 and the antibiotic ciprofloxacin on the gut microbiota of healthy C57BL/6 mouse model over a four-week period. Fecal microbiota were analyzed using 16s rRNA nanopore long-read sequencing. The findings revealed that OM-89 effectively preserved the overall diversity and balance of the gut microbiome. In contrast, ciprofloxacin treatment resulted in marked disruptions of gut microbial composition, characterized by reductions in richness and evenness, accompanied by increases in the relative abundance of Akkermansia muciniphila and Phocaeicola vulgatus . This suggests that OM-89, unlike antibiotics, exerts a milder impact on the gut microbiota in healthy mice. Future studies using uropathogenic infection models are essential to determine whether the preservation of gut microbiota by OM-89 directly correlates with the prevention of rUTI recurrence. Furthermore, clinical investigations are warranted to confirm the tangible clinical benefits of these effects in patients. Such investigations will clarify the previously unclear mechanisms of OM-89 from the novel perspective of gut microbial balance, thereby establishing a clinical rationale for rUTI prevention. © 2026 The Author(s).