A urinary tract infection (UTI) is an infection that takes place in any part of the urinary system, including the bladder, kidneys, ureters, and urethra, with the most common locations being in the lower parts of the urinary tract. UTIs are typically caused by bacteria entering the urinary tract and spreading into the bladder or other parts of the urinary system. In more than 90% of cases, the bacteria known as E. coli is responsible for causing this. While the urinary tract is designed to protect itself against bacteria, sometimes defenses fail – the result of which is a full-blown infection that requires medical intervention to treat.