Lab-Grown Bacteria-Killing Viruses and a Stool Transplant Eased Repeat UTIs in Two of Three Women

Three women with stubborn, recurring urinary tract infections took part in the first human test of a two-front attack: lab-grown viruses that selectively kill the bacteria, then, in two of three cases, a stool transplant aimed at restoring the gut microbiome that re-seeds the bladder.

The case series, published in Nature Microbiology and described in GEN, ran at University Hospital Cologne between May and July 2023. Recurrent UTIs, defined as two infections in six months or three in a year, disproportionately affect women and drive more than 15% of outpatient antibiotic prescriptions, fueling the search for alternatives as resistance rises.

Phage therapy was given orally and directly into the bladder via catheter for eight days, outside acute infections. Two of the three then received a fecal microbiota transplant. The logic: phages clear the pathogen, FMT resets the gut reservoir that keeps re-seeding the urinary tract.

Over two years of follow-up, both combination-therapy patients had long-term drops in infections. The phage-only patient kept having episodes, though milder. E. coli was still detected in follow-up samples for all three, meaning infections eased rather than cleared, but quality-of-life scores improved and antibiotic use fell substantially.

"While phage therapy acts to remove the pathogen, FMT aims to restore a healthy microbiome, combining both immediate and long-term effects," said Lena Biehl, MD, PhD, group leader at Fraunhofer ITMP, in the case series. The researcher flagged the limit: three patients is too few to call this a treatment. The controlled test is REPhRAME, a €15 million (about US$16 million at recent exchange rates) Horizon Europe program of 16 partners led by Universitätsmedizin Frankfurt, with the trial scheduled for June 2027.