Insidious clinical presentation of uncommon infective endocarditis caused by Cardiobacterium species

Infective endocarditis (IE) is a fatal disease caused by a wide range of pathogens, with a strong prevalence of Gram-positive bacteria. In this paper we describe two peculiar cases of Cardiobacterium spp. endocarditis in young men. These case reports emphasize the insidious clinical presentation of HACEK IE and lead to a brief review of the literature and discussion on this uncommon cause of infective endocarditis. One case is a man with a prior diagnosis of myxomatous mitral valve, presenting with neurological symptoms and a mycotic aneurysm of the right anterior cerebral artery. The second case was a man with no prior medical history, presenting with fever, lumbar and right-leg pain, which led to a diagnosis of atrial myxoma. The presence of congenital cardiac malformations and an insidious onset with early presentation but unusual or non-specific symptoms are evidenced with a high prevalence in this group of patients. The diagnostic workup including cultural examinations are analyzed in the discussion. We noticed, in accordance with recent literature, a time to positivity of blood cultures longer than for typical agents, but mostly inferior to 5 days. The majority of the reported cases went to surgery, while therapeutical regimens alternative to cephalosporins, especially quinolones, are recently gaining interest. While mortality rates are lower than those observed in other cases of IE, Cardiobacterium spp. IE is characterized by a high burden of complications, leading to an often-atypical presentation.