Why are iv drug users more susceptible to endocarditis?

Dirty needles: Endocarditis is more likely to occur when there are a lot of bacteria in the blood stream. Iv drug abusers break their skin frequently; the skin acts as a normal barrier to infection. Also, if sterile technique is not used (which it rarely is), bacteria are introduced directly into the blood stream. In addition, the immune system of drug addicts is often compromised.