Identification of Cardiobacterium valvarum: shedding light on infective endocarditis diagnosis

The genus Cardiobacterium is a fastidious, Gram-negative rod belonging to the HACEK group (Haemophilus species excluding H. inf luenzae, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella). A total of 399 cases of infective endocarditis caused by HACEK species have been reported, accounting for approximately 3% of all endocarditis cases [1]. Cardiobacterium valvarum was first identified in a patient with infective endocarditis [2]. Although C. valvarum can cause infections in other anatomical sites [3], it is predominantly associated with infective endocarditis [2,4]. Here, we present how a preconceived notion of this bacterial species contributed to the diagnosis of a hidden, potentially fatal condition.