Urinary tract infection
A urinary tract infection (UTI) is an infection caused by bacteria in the urinary tract. The urinary tract is: the kidneys, ureters, the urinary bladder, and urethra. Symptoms of a UTI may be painful peeing, frequent peeing, or wanting to pee (or both). Symptoms of a kidney infection include fever and side and back pain. In older people and young children, the symptoms are not always clear. Often the main cause of a UTI is the bacteria Escherichia coli. Other bacteria, viruses, or fungi may be the cause less often.