Urinary tract infection: a moving target.

Urinary tract infection is an old problem that continues to present new challenges. The purpose of this special edition is to pull together new basic scientific information regarding the pathogenesis of infection and to review the state of the art in the evaluation and treatment of urinary tract infection in some of the more complex or challenging clinical settings. The goal has been more than a summarization of current knowledge; the intent has been to highlight areas of uncertainty, thereby emphasizing the need for further investigation. Herein we briefly mention four clinical settings for urinary tract infection that, in our opinion, present important new or evolving challenges and are particularly fertile areas for further work.