A urinary tract infection (UTI) occurs when a bacterium, such as uropathogenic Escherichia coli, overcomes host defenses and adheres to, multiplies, and persists in the urinary tract.
- Simple UTI
- These infections involve the bladder and are typically initial infections with no concurrent disease or underlying structural or functional abnormality (ie, no compromise of host defense mechanisms).
- Complicated UTI
- These infections are associated with pyelonephritis, prostatitis, concurrent systemic diseases (diabetes mellitus, hyper-adrenocorticism), and either systemic (corticosteroid use) or local (indwelling urinary catheter, uroliths, neoplasia) alterations in immunity through compromised host defense mechanisms.