A urinary tract infection (UTI) is an infection that affects any part of the urinary system, which includes the kidneys, ureters, bladder, and urethra. Most infections involve the lower urinary tract — the bladder and the urethra. UTIs are more common in women than men and can cause a range of symptoms from mild discomfort to severe health problems. UTIs are typically caused by bacteria, although fungi or viruses can also be culprits. The most common bacterium responsible for UTIs is Escherichia coli (E. coli), which normally lives in the intestines.
