Bacteriophage-mediated reduction of uropathogenic E. coli from the urogenital epithelium

Urinary tract infections (UTIs), primarily caused by uropathogenic Escherichia coli (UPEC), affect millions annually. UPEC gains access to the urinary tract through mucosal reservoirs including the vaginal tract. With rising antibiotic resistance and frequent recurrence, alternative non-antibiotic strategies like bacteriophage (phage) therapy are gaining attention. We explored the potential of a lytic phage, {Phi}HP3, as well as a phage cocktail to decolonize UPEC from the urogenital tract using in vitro and in vivo models. Phage significantly inhibited UPEC growth in both bacteriologic medium and simulated vaginal fluid. Pretreatment of human vaginal epithelial cells (VK2/E6E7) and bladder carcinoma cells (HTB-9) with phage reduced adhesion and invasion of UPEC compared with controls. Phage treatment was further able to reduce intracellular UPEC in VK2 cells. Notably, phage pretreatment did not impact phage resistant UPEC strains, indicating that phage lysis was the primary driver of phenotypes. Live confocal microscopy confirmed interaction of phage particles with UPEC and with both epithelial cell lines. In vivo, daily intravaginal {Phi}HP3 administration in humanized microbiota mice significantly reduced vaginal UPEC burden after 4 days. Treatment with a phage cocktail also reduced vaginal and cervical tissue burdens by day 7 post-treatment. UPEC dissemination was observed to uterine and kidney tissues, but burdens were not different between phage and mock-treated groups. In conclusion, we demonstrate that phage and phage cocktails can modestly reduce UPEC urogenital colonization, highlighting the potential of phage therapy as a viable treatment option for UTI prevention. IMPORTANCEUrinary tract infections (UTIs) are among the most common infections worldwide, with millions of cases each year. Due to frequent recurrence and increasing antibiotic resistance, UTIs are becoming more difficult to treat, and non-antibiotic prevention options remain limited. The bacteria responsible for UTIs, such as uropathogenic E. coli (UPEC), often colonize other body sites, such as the intestines or vagina, before causing infection. In this study, we investigated whether bacteriophage (phage), viruses that infect bacteria, could reduce UPEC colonization. We found that phage treatment decreased UPEC adherence to vaginal and bladder cell lines, but only modestly reduced UPEC vaginal colonization in a mouse model. These findings suggest that phages may offer a potential strategy for UTI prevention, though further research is needed to optimize their therapeutic use.