Cardiobacterium hominis is most classically associated with which condition?

• A. Endocarditis
• B. Urinary tract infection
• C. Meningitis
• D. Pneumonia

Answer: (A)

Cardiobacterium hominis is a classic member of the HACEK group that is strongly linked to infective endocarditis, particularly the subacute form on damaged or abnormal heart valves. These organisms are fastidious and can produce culture-negative endocarditis, so the association with a gradual onset fever, new or changing heart murmur, and embolic phenomena is a key clue. While it can appear in other infections in theory, its well-established, textbook link is with endocarditis, making that the best answer. Urinary tract infection, meningitis, and pneumonia are not the typical clinical contexts for this organism.