What is the most common organism associated with infective endocarditis in IV drug users?

Infective endocarditis is a serious infection of the heart valves or endocardium, and the causative organisms can vary depending on the patient's risk factors and clinical history. In intravenous drug users, the typical route of infection involves the introduction of bacteria into the bloodstream via contaminated needles or equipment.

Staphylococcus aureus is particularly associated with infective endocarditis in this population due to its ability to skin flora and its virulence. It is a hardy organism that can easily enter the bloodstream, especially when common practices related to IV drug use compromise skin integrity. The ability of Staphylococcus aureus to rapidly colonize valves, especially prosthetic ones, and its capacity to cause severe disease make it the most common pathogen in these cases.

In contrast, organisms such as Streptococcus viridans and Enterococcus faecalis are usually linked with infective endocarditis in patients without IV drug use or those who have other underlying heart conditions. The HACEK group, which includes Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella species, is a rare cause of endocarditis compared to Staphylococcus aureus and is more commonly associated with native valve endocard