What are some causes of E. coli bacteria in urine samples?

Urinary tract infections are a common cause of E. coli bacteria in urine samples, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Bacteria from the bowels causes the majority of urinary tract infections, and E. coli is by and far the most common offender.

Doctors diagnose urinary tract infections by a combination of urine test results and infection symptoms, explains the National Institute of Diabetes and Digestive and Kidney Diseases. The urine test consists of both a "clean catch" and a midstream sample, to obtain an indicative sample, as healthy individuals also have bacteria in their urine.