Final answer:
The tricuspid valve is most commonly affected by endocarditis in intravenous drug users, with Staphylococcus aureus being a common causative agent. Acute bacterial endocarditis is more severe and rapid than subacute bacterial endocarditis, but both require aggressive treatment with intravenous antibiotics.
Step-by-step explanation:
The most common valve affected in IVDU (Intravenous Drug Use) endocarditis is the tricuspid valve. This type of endocarditis is often caused by bacteria such as Staphylococcus aureus, which can enter the bloodstream during activities like injections. In contrast to conditions like mitral regurgitation, which is commonly found in the general population, IVDU endocarditis typically affects the tricuspid valve because it is the first valve encountered by the pathogen following venous injection.
Compare Acute and Subacute Bacterial Endocarditis
Acute bacterial endocarditis presents rapidly and is more severe, often caused by aggressive bacteria and can lead to rapid deterioration of the valves. Subacute bacterial endocarditis, however, has a slower onset with milder symptoms. The treatment for both usually involves high doses of intravenous antibiotics, but the clinical approach may vary depending on the severity and progression of the valve damage.