Which organism is most often associated with endocarditis?

• A. Neisseria gonorrhoeae
• B. Kingella denitrificans
• C. Haemophilus influenzae
• D. Pasteurella multocida

Answer: (B)

Endocarditis is most characteristically linked to organisms that are part of the oropharyngeal flora and grow slowly in culture, known collectively as the HACEK group. Kingella species, including Kingella denitrificans, are classic causes within this group and are well recognized for producing endocarditis, often with a subacute course due to their fastidious growth. Because of their slow, difficult-to-grow nature, they may require extended or specialized culture conditions, which fits the scenario of endocarditis being associated with this organism. While Neisseria gonorrhoeae, Haemophilus influenzae, and Pasteurella multocida can also cause endocarditis, they are less emblematic of endocarditis in standard teaching than the HACEK organisms, making Kingella denitrificans the best match here.