Staphylococcus aureus is a leading cause of both community-acquired and healthcare-associated bacteremia. Several important underlying conditions predispose patients to the development of S. aureus bacteremia (SAB). The morbidity and mortality of SAB is high even when appropriate therapy is given.
The presence of individual risk factors substantially affects clinical management. Thus, clinicians need to specifically inquire as to the presence or absence of these risk factors before making clinical decisions regarding treatment.
The epidemiology of and risk factors for SAB in adults will be reviewed here. The treatment of SAB is discussed separately. (See "Clinical approach to Staphylococcus aureus bacteremia in adults".)
Bacteremia due to S. aureus can be classified into three categories: healthcare-associated hospital onset (nosocomial), community-acquired, and healthcare-associated community onset (non-nosocomial) (eg, long-term care facilities) . In a prospective cohort study of 504 bloodstream infections (BSIs) seen at an academic center and two community hospitals in North Carolina between late 2000 and early 2001, 35 percent were nosocomial, 28 percent were community-acquired, and 37 percent were healthcare-associated community-onset . Methicillin-resistant S. aureus accounted for most nosocomial and healthcare-associated community-onset infections (61 and 52 percent, respectively) but only a small proportion of community-acquired infections (14 percent).
Nosocomial — SAB has become a leading cause of nosocomial bloodstream infections (BSIs) in the United States. This was illustrated in a prospective analysis of over 24,000 nosocomial BSIs occurring in 49 hospitals in the United States between 1995 and 2002, S. aureus was the second most common cause after coagulase-negative staphylococci, accounting for 20 percent of cases . The proportion of S. aureus isolates that were due to methicillin-resistant increased from 22 percent in 1995 to 57 percent in 2001.