Subacute infective endocarditis in a healthy man with native heart valves by Cardiobacterium hominis: a rare presentation from the HACEK group

Infective endocarditis (IE) remains a serious condition with a high mortality rate, even with recent improvements in its diagnosis and management. HACEK organisms, which include Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae, are gram-negative bacteria naturally found in the human mouth and upper respiratory tract. Despite their limited pathogenic potential, HACEK organisms account for 1-3% of all cases of infective endocarditis. This form of endocarditis primarily affects individuals with pre-existing heart conditions or prosthetic heart valves. The disease typically progresses slowly, with an average diagnostic delay ranging from one month for Haemophilus spp. to three months for Aggregatibacter and Cardiobacterium spp. We present a case of a 40-year-old previously healthy man who has been managed for HACEK-IE in native valves without a pre-existing cardiac disease. His blood cultures yielded a gram-negative bacillus which was identified as Cardiobacterium hominis. He was managed with third generation cephalosporin for six weeks with a good clinical outcome. This case highlights the importance of considering HACEK-IE in a patient with native heart valves.