A 21-year-old man known to paramedics as an IV heroin user is found unconscious in the park. Paramedics are unable to revive him using naloxone or flumazenil. An autopsy determines that the man had infective endocarditis (IE). What is the pathophysiology associated with this disease?

Choice A reason: Rheumatic fever can lead to valvular heart disease, particularly affecting the left-sided valves, but it is not the primary pathophysiology in IV drug users with infective endocarditis. It is unrelated to the acute presentation in this case. Choice B reason: IV drug use introduces pathogens directly into the bloodstream, often leading to infection of the right-sided heart valves, particularly the tricuspid valve. Staphylococcus aureus is the most common causative organism. This pathophysiology is well-documented and explains the development of IE in IV drug users. Choice C reason: While HIV may increase susceptibility to infections due to immunosuppression, it is not the direct cause of infective endocarditis. The primary mechanism in this case is bacterial seeding of the heart valves via IV drug use. Choice D reason: This statement is incorrect. IV drug use is a major risk factor for infective endocarditis due to repeated introduction of bacteria into the bloodstream and damage to cardiac valves.