Bacteroides fragilis perinephric abscess.

Although urinary tract infection caused by Bacteroides fragilis has been recognized since the turn of the century it is not frequently recognized in clinical practice. Only a small number of significant upper urinary tract infections in which Bacteroides fragilis has had a significant pathogenic role have been reported previously. The use of systemic metronidazole in the treatment of this rare and unusually refractory form of urinary tract infection is described.