Urinary tract infection causes
Normally, the urinary tract is sterile. That means it does not have any microorganisms like bacteria living in it. However, bacteria from another area can make its way into your urinary tract (usually via the urethra), multiply, and cause a UTI. The main cause is E. coli, normally found in the digestive tract.
E. coli is responsible for >85% of all UTIs and also recurrent UTIs.1 However, there are other bacteria that can cause UTIs. Your doctor may ask for a urine sample to confirm which bug has infected your urinary tract so that they can recommend an appropriate treatment.
1. Barnett BJ and Stephens DS. Am J Med Sci. 1997;314(2):245−249.