Suppurative polyarthritis following a rat bite.

A 62 year old healthy Chinese man was admitted to hospital three weeks after a rat bit his left foot. Four days after the bite he developed pain over his left foot followed by pain and swelling in both knees, elbows, wrists, the small joints of both hands, and the left ankle. He had no fever or constitutional symptoms. On admission he was febrile and jaundiced. His blood pressure was 110/70 mm Hg. No cardiac murmurs were heard. There was no right hypochondrial tenderness or hepatomegaly. There was synovitis affecting his wrists, interphalangeal and metacarpophalangeal joints of the hands, effusions in his right knee, right ankle, and left midtarsal joint (fig 1). Figure 1 Synovitis of the right ankle and left midtarsal joint with the site of the rat bite (circled), which has healed. His haemoglobin was 125 g/l, white cell count 29.3×109/l with 90% polymorphs, platelet count 621×109/l. The C reactive protein was 197 mg/l. Renal function was normal. Liver function tests showed a cholestatic hepatitis with serum bilirubin 55 μmol/l, alkaline phosphatase 399 U/l, alanine aminotransferase 230 U/l, and aspartate aminotransferase 63 U/l. Hepatitis B and C serology findings were negative. Pus, aspirated from the right knee, contained 90 000 white cells/μl with 98% polymorphs. The Gram stain showed regular Gram negative intracellular bacilli. With the history and the Gram stain finding, both the microbiologist and rheumatologist were alerted to the possibility of streptobacillary septic arthritis. Oral ciprofloxacin and doxycycline were empirically started as the patient had …