Cardiobacterium hominis /ˌkɑːrdiəʊbækˈtɪəriəm ˈhɒmɪnɪs/ (KAR-dee-oh-bak-TEER-ee-um HOM-i-nis) is a microaerophilic, pleomorphic, fastidious, Gram-negative bacterium part of the Cardiobacteriaceae family and the HACEK group.
[1] It is most commonly found in the human microbiota, specifically the oropharyngeal region including the mouth and upper part of the respiratory tract.
[2] Cardiobacterium hominis was originally discovered in 1962 based on analysis of four cases of Infective endocarditis over ten months.
[5] Upon its first isolation, researchers described Cardiobacterium hominis, which was unrecognized then, as a Pasteurella-like organism and categorized as group "II-D" by the Centers for Disease Control and Prevention.
[5] In 1964, researchers I. J. Slotnick and M. Dougherty from the Laboratory of Bacteriology, St. Jude Hospital and Department of Microbiology, University of Tennessee found Cardiobacterium hominis in a 54-year-old male patient with infective endocarditis.
[9] Overall, the sequenced T05791 strain of Cardiobacterium hominis was found to have one circular chromosome with a genome size of 2.7 Megabases (Mb) and a G+C content of 59%.
[13] Its metabolite utilization includes the ability to build acid from glucose, fructose, and maltose and it possesses some of the physiological and morphological advantages relative to this genus of bacteria including, the ability to live in low oxygen environments, heat and cold resistance (mesophilic), spore formation, and antibiotic resistance except to penicillin.
[2] These cases include occurrence of infective endocarditis that led to aortic root complications which severely threatened the patient's life.
[16] Researchers found out of 56 patients with infective endocarditis caused by Gram-negative bacteria from 1958 through 1979 at the Mayo Clinic, 6 cases were linked to Cardiobacterium hominis.
HACEK endocarditis targets patients with a prior heart disease or artificial valves with often an insidious course showing a diagnosis delay of 3 months.
[18] Fastidious Gram-negative bacteria such as Cardiobacterium hominis along with Eikenella corrodens and Kingella kingae mainly inhabiting in the oral and upper respiratory tract in humans are responsible for 1–3% of infective endocarditis.