Septic Polyarthritis Caused by Streptobacillus moniliformis.

Streptobacillus moniliformis is a pleomorphic, fastidious gram-negative bacillus that colonizes rodent respiratory tracts and causes rat-bite fever in humans. Rat-bite fever is associated with septic arthritis, usually monoarticular or pauciarticular. We report a rare case of polyarticular septic arthritis caused by S. moniliformis; the disease was initially misdiagnosed as inflammatory arthritis.