UTIs are bacterial infections of any part of the urinary tract causing inflammation. More than half of all women in the UK experience a UTI in their lifetime and around a quarter have recurrent episodes. Most UTI bacteria move up from the colon (large intestine), but they might also be caused by bacteria from the vagina.
Lactobacillus are the primary bacteria in the vagina of healthy women as they are anaerobic and survive in this area. This species of bacteria is known to prevent potentially infective bacteria from entering the urinary tract.