We report a case of rat bite fever caused by Streptobacillus moniliformis in Taiwan. It manifested as prosthetic valve endocarditis, which was cured by cardiac valve replacement and antimicrobial therapy. The DNA sequence of the 16S rRNA gene of S. moniliformis was detected in valve specimens by PCR and nucleotide sequencing.
CASE REPORTA 60-year-old female was admitted to a university hospital in Tainan in southern Taiwan with a 2-week history of intermittent fever. Symptoms began 1 week later, after a rodent bite over her right big toe in her house in early October 2006. Pus was noted initially, and the wound healed subsequently. Associated symptoms were general weakness and body weight loss. She had received mechanical valve replacement for the rheumatic mitral valve 17 years ago. She was regularly followed up in a cardiac surgical clinic and took coumadin and trichloremthiazide regularly.On admission, her temperature was 38.1°C, her heart rate 82 beats/min, and her respiratory rate 18 breaths/min. Her blood pressure was 139/69 mm Hg. Physical examinations showed no skin lesions or joint inflammation. The heart sound of the mitral mechanical valve was clear, but a new grade 3/6 systolic murmur over the left lower sternum border radiating to the left apex was noted on cardiac auscultation. Laboratory studies revealed the following: leukocyte count, 15,100/mm 3 ; neutrophil level, 94%; lymphocyte level, 4%; hemoglobin level, 8.2 g/dl; and platelet count, 134,000/mm 3 . Electrolyte levels and renal and liver functions were normal. The serum level of C-reactive protein was 162.9 mg/liter (the normal level is Ͻ8 mg/liter) and the erythrocyte sedimentation rate 14 mm/h (the normal level is Ͻ15 mm/h). Transesophageal echocardiography revealed a dehiscence of the mechanical mitral valve, with severe posterior eccentric mitral regurgitation, and a fluttering mass with a size of 0.8 cm located at the lateral mitral valve annulus. She received mitral valve replacement for valve dysfunction on the 7th hospital day and became afebrile after the operation. Endocarditis with vegetations was confirmed by pathological examinations.