Endocarditis Due to Cardiobacterium hominis in a 4-Year-Old Boy, Complicated by Right Lower Lobe Pulmonary Artery Mycotic Aneurysm.

Abstract

The fastidious, slow-growing bacteria of the species designated by the “HACEK” acronym (Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus paraphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens ,a ndKingella kingae) are important causes of gram-negative endocarditis [1]. Haemophilus species account for the largest number of such infections in children, followed by K kingae, then A actinomycetemcomitans [2, 3]. In children, we found no published reports of E corrodens endocarditis and only 2 reports of C hominis endocarditis; 1 in a 17-year-old in the United Kingdom and the other in a 3-year-old in Japan [4, 5]. To our knowledge, we describe here the first reported case of endocarditis due to C hominis in a child in the western hemisphere, and, for this infection, the unique occurrence of a large pulmonary vessel mycotic aneurysm. CASE REPORT The patient was a 4-year-old male with DiGeorge syndrome, developmental delay and complex congenital heart disease. His heart disease consisted of tetralogy of Fallot with pulmonary atresia, small pulmonary arteries, and major aortopulmonary collaterals. He had hypoparathyroidism but had normal T-cell numbers and function. At 3 months of age, he underwent placement of a right ventricle-to-pulmonary artery (RV-PA) non-valved conduit. At 18 months of age he underwent ventricular septal defect (VSD) patch closure, replacement of his RV-PA conduit with a Contegra 16-mm valved conduit, and patch plasty of the left pulmonary artery. His most recent echocardiogram, 1 month before presentation, had revealed an insignificant residual VSD at the patch margin, trivial tricuspid regurgitation, RV pressure equal to ¾ systemic pressure, moderate RV hypertrophy, mild aortic insufficiency, and normal biventricular function. The patient presented to the Mount Sinai Kravis Children’s Hospital emergency department with a 1-week history of fever as high as 102 o F, intermittent cough, irritability, and decreased appetite. Physical findings on presentation included mild irritability, temperature of 38.9 o C, abnormal facies consistent with DiGeorge syndrome, coarse breath sounds bilaterally, and a harsh, grade 3/6 systolic heart murmur, loudest at the base, radiating to the back. Dentition was intact, and there were no mucosal or skin lesions. Pulse oximetry revealed reduced oxygen saturation, and a chest radiograph showed bilateral patchy areas of opacification. Blood was obtained for cultures and other laboratory studies, treatment for presumed pneumonia was begun with intravenous ceftriaxone and oral azithromycin, and the patient was admitted to the inpatient unit for continued management. The peripheral white blood count was 16 900/mm 3 , with 73% neutrophils, and the serum C-reactive protein level was 162 µg/L. The single blood culture drawn at admission was reported positive at 64 hours (Bactec 9240 System; Becton Dickinson, Franklin Lakes, NJ) for small gram-negative bacilli. The isolate was subsequently identified as C hominis and was found to be susceptible to ceftriaxone (VITEK 2; bioMerieux, Durham, NC). Subsequent single blood cultures drawn on hospital days 2, 4, and 5 all were negative. A transthoracic echocardiogram showed a mobile echobright structure consistent with a vegetation near the