<s>[INST] What is the major cause of a urinary tract infection? [/INST] E. coli cause more than 90% of bladder infections. E. coli typically exist in your lower intestines (large intestine). Source: Cleveland Clinic. Link: https://my.clevelandclinic.org/health/diseases/9135-urinary-tract-infections. Field: Urology. Disease: Urinary Tract Infection  </s>