Streptobacillary fever

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A 77-year-old farmer presented with a two-week history of fever, chills, nausea, and generalized symmetric polyarthritis. One week before his illness, the patient was bitten on the right wrist by a rat. His temperature was 38.3 °C. There was a 3-cm raised tender papule at the inoculation site. The left sternoclavicular joint, several proximal interphalangeal and metacarpal joints, and both wrists and ankles were painful and swollen. Synovial fluid white blood cell count was 104,000/mm3, with 90% neutrophils and 8% band forms. Gram’s stain demonstrated many gram-negative coccobacillary organisms. The patient was initially treated with oxacillin and ampicillin (8 g/day of each antibiotic) for two days and then with procaine penicillin (600,000 units administered intramuscularly twice a day) for a total of 14 days. The arthritis symptoms gradually resolved. Streptobacillus moniliformis grew from a synovial fluid culture from the left ankle and the lesion of the right wrist. This case report demonstrates the rare occurrence of rat-bite fever manifested by septic arthritis successfully treated with penicillin.