Staphylococcus aureus infections in injection drug users: risk factors and prevention strategies

Infections, in particular soft tissue infections (cellulitis, skin abscesses), are the leading cause for emergency department visits and hospital admissions of drug injection users (IDUs). Staphylococcus aureus is the most relevant bacterial pathogen in this population. It is the main cause of soft tissue infections and of severe infections such as endocarditis and bacteremia. Moreover, epidemic spread of methicillin-resistant S. aureus (MRSA) among IDUs has occurred in Europe and North America. Nasal carriage of S. aureus is associated with an increased risk of subsequent S. aureus infections, and it has been shown that active IDUs have a higher rate of colonization with S. aureus than the general population. However, it is still unknown why an individual carries S. aureus. In particular, repeated injections do not appear to be the main predisposing factor for S. aureus carriage. Infections associated with injection drug use are frequently the consequence of the illegal status of street drugs. Harm reduction programs, including needle exchange programs, safer injecting facilities and injection opiate substitution programs can reduce the incidence of infections among severely addicted IDUs.