Rat bite fever mimicking rheumatoid arthritis.

We report a case of Streptobacillus moniliformis polyarthritis mimicking a rheumatoid arthritis, in a pet shop employee. In culture of fluid joint growth a curious Gram-negative bacillus was identified by polymerase chain reaction as Streptobacillus moniliformis. The outcome was good after surgical debridment and rifampin-clindamycin combination during 4 weeks.