In young, sexually active women, about 80 percent of UTIs are caused by E. coli. Conventional thinking holds that recurrence occurs when E. coli is reintroduced into the urinary tract. But the new research suggests another way for a subsequent UTI to develop: The vaginal bacterium Gardnerella vaginalis triggers E. coli already hiding in the bladder to cause another UTI. G. vaginalis also may be a contributor to more serious — and potentially deadly — kidney infections, the study suggests. “We found tha

Source: Vaginal bacteria can trigger recurrent UTIs, study shows: Findings help explain UTI link to sexual activity — ScienceDaily