Rat-bite fever as a cause of septic arthritis: a diagnostic dilemma.

Rat-bite fever results from an infection with the organism Streptobacillus moniliformis. Symptomatic patients often present with fever, malaise, cough, maculopapular rash, and occasional arthritis, and usually have a history of rodent exposure. This report describes a patient with rat-bite fever resulting in suppurative arthritis. The patient's diagnosis was made by culture of S moniliformis from his left wrist. The diagnosis was delayed, however, owing to the lack of an exposure history, atypical clinical presentation, and the unusual microbiologic characteristics shown by this organism.