Bacterial endocarditis due to Kingella kingae is rare. As far as we learned, there are only 19 cases of IE due to this organism reported in the literature, and no case reported in Japan. We describe here a patient with endocarditis caused by K. kingae.
A 33 years house-wife, previously diagnosed as SLE, was presented with spiking fever and polyarthralgia. On examination, she was feverish but well-oriented. The body temperature was 40.0°C. The butterfly-like erythema was noticed on her face. The mitral regurgitant murmur was audible. The white blood cell count was 3400 with 6% band form, 52% segmented neutrophiles, 4% eosinophiles, and 28% lymphocytes. LE cells were positive. ANA was positive at a titer of 1: 320, with hypocomplementemia. She was given high dose of steroid, under the diagnosis of acute exacerbation of SLE, followed by partial resolution of high fever. On 6th hospital day, gram-negative coccoid bacilli were grown in a blood culture obtained on the 3rd day. Echocardiogram revealed large, mobile vegetation attached on posterior leaflet of the mitral valve. Same GNR was grown three times consecutively. A diagnosis of IE due to unspecified GNR was done.
She was started on ceftizoxime 1g d. i. v. every 6h, with peak serum bacteriocidal titer of 1: 128, and trough SBT of 1: 32. On 20th day, cefotetan 2g d.i. v. every 12h was substituted for CZX, with same peak and trough SBT as CZX, because of difficult maintenance of blood access. Her clinical course was complicated with major emboli to the right popliteal artery on 22nd hospital day, and renal infarction on 25th day. Echocardiogram taken after the events revealed no vegetation of the mitral valve. Medical treatment was completed after 35 days of antibiotics. No relapse was observed during one year followup period.
K. kingae, considered as human oral commensal, is oxidase positive, catalase negative and nonmotile gram negative coccoid bacillus. Differentiation from other fastidious GNR was made by the characteristic beta-like homolysis on sheep blood agar. Rapid NH system (Innovative Diagnostic System Inc, USA) was also useful for the rapid identification of K. kingae.