Complicated urinary tract infections.

The term complicated urinary tract infection is usually used to convey an infection that occurs in a patient with a structural or functional abnormality impeding urine flow, or in a host with altered defences. The distinction between complicated and uncomplicated infections is important because, when complicating factors are present, antimicrobial resistance is more common and the response to therapy is often disappointing, even with agents active against the causative microbial pathogen. In addition, severe complications frequently occur which may lead to urosepsis, renal scarring or even end-stage disease. Drug treatment of complicated urinary tract infections often must be complemented with endoscopic and/or surgical intervention. Only a few well designed treatment studies have been published and therefore sources for definitive therapeutic guidelines remain inadequate.