ABSTRACT
The HACEK group of bacteria (Haemophilus parainfluenzae, H. aphrophilus, H. paraphrophilus, Actinobacilus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corodens, and Kingella kingae) are the normal flora of the upper respiratory tract and oropharynx. The organisms infect abnormal cardiac valves, causing subacute native endocarditis or prosthetic valve endocarditis more than one year after valve surgery. Haemophilus species are responsible for only 0.5~1% of all infective endocarditis cases. Embolization occurs in 60% and the mortality rate ranges from 16~45% of cases of infective endocarditis caused by H. parainfluenzae. We experienced a case of infective endocarditis due to H. parainfluenzae in a 37-year-old male admitted with high fever, chills, nausea & vomiting, chest discomfort, and blurred vision. The organism was isolated from a blood culture and was identified as H. parainfluenzae by factor V requirement, negativity at urea, positivity at ornithine decarboxylase, and acid production from glucose and maltose. The patient was treated with antibiotics and symptoms and signs were improved