[Prosthetic endocarditis caused by Kingella denitrificans in a patient with diabetes mellitus]

Infective endocarditis caused by Kingella denitrificans occurs rarely. A review of the literature reveals only 6 cases of endocarditis caused by the bacillus. K. denitrificans is normally a commensal of the upper respiratory airways, may exceptionally be responsible for endocarditis. A case of possible prosthetic endocarditis caused by K. denitrificans is presented. A 78-year-old male with Type II diabetes was admitted to the hospital complaining of fever, a sore throat and arthralgia. He underwent replacement surgery of a St. Jude medical prosthesis for aortic stenosis at the age of 75. The only physical findings at admission were a temperature of 38.2 degrees C and murmurs of mild mitral regurgitation. The liver and spleen were not palpable, and there were no skin or eye lesions. Laboratory findings were as follows: white blood cell count 9500/microliters with 77% neutrophils, erythrocyte sedimentation rate 71 mm/h (Westergren), blood urea nitrogen 50.2 mg/dl, serum creatinine 1.7 mg/dl and C-reactive protein 22.2 mg/dl. The Gram-negative bacillus isolated from the blood was identified as K. denitrificans by the identification system, namely ID test.FN-20 rapid (Nissui, Japan). Although an echocardiogram detected no vegetation, infective endocarditis was diagnosed because the same bacillus was detected by separate blood cultures and an obvious source of infection was not found other than the prosthetic valve. Initial treatment was flomoxef, which was changed to Ampicillin 2 g/day after K. denitrificans was identified. Ampicillin continued for 6 weeks. The clinical course was good and he did not require further surgery. He has been afebrile for 2 years after completing treatment. This case represents the first report of prosthetic valve endocarditis caused by K. denitrificans in Japan.