To infect the urinary system, a micro-organism usually has to enter through the urethra or, rarely, through the bloodstream. The main cause is E. coli, normally found in the digestive tract.

E. coli is responsible for >85% of all UTIs.1

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.

Risk factors

Some people may be more prone to UTIs than others.

  • Sexually-active women
  • Women, due to the anatomy of the urethra being relatively short, only about 4 cm long
  • People with urinary catheters who cannot empty their own bladder
  • People with an altered immune system, including people with diabetes
  • Men with prostate problems that interfere with bladder emptying
  • Babies, especially those with physical problems of the urinary system


  1. Everyday Health. The Connection Between E. coli and Urinary Tract Infections (UTIs). Available from Accessed 21 July 2021.