Which statement best describes acute endocarditis?

• A. It is usually caused by Staphylococcus aureus and often occurs in IV drug users.
• B. It is typically associated with prior valve abnormalities and dental procedures.
• C. It arises mainly after dental procedures due to viridans streptococci.
• D. It is typically a slow, indolent infection with low fever.

Answer: (A)

Acute endocarditis is defined by a rapid, aggressive infection of the heart valves caused by a highly virulent organism. Staphylococcus aureus fits this picture best because it readily invades and destroys valve tissue, leading to a fast-onset, high fevers and often septic illness. In intravenous drug users, the infection frequently starts on the right-sided valves (like the tricuspid valve) due to direct inoculation of bacteria from nonsterile injections, which is a classic scenario for acute endocarditis.

The other statements describe a different pattern: infections that are more indolent and typically linked to viridans streptococci, often after dental work, and frequently involving damaged valves. Those features align with subacute endocarditis, which tends to progress slowly with milder symptoms and lower-grade fevers, rather than the rapid, fulminant course seen with Staphylococcus aureus.