what is the cause of a urinary tract infection
The urine is normally sterile. An infection occurs when bacteria get into the urine and begin to grow. The infection usually starts at the opening of the urethra where the urine leaves the body and moves upward into the urinary tract. 1  The culprit in at least 90% of uncomplicated infections is a type of bacteria called Escherichia coli, better know as E. coli.