Epidemiology of Staphylococcus aureus blood and skin and soft tissue infections in the US military health system, 2005-2010

JAMA. 2012 Jul 4;308(1):50-9. doi: 10.1001/jama.2012.7139.


Context: Rates of hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) infections are reported as decreasing, but recent rates of community-onset S. aureus infections are less known.

Objectives: To characterize the overall and annual incidence rates of community-onset and hospital-onset S. aureus bacteremia and skin and soft tissue infections (SSTIs) in a national health care system and to evaluate trends in the incidence rates of S. aureus bacteremia and SSTIs and the proportion due to MRSA.

Design, setting, and participants: Observational study of all Department of Defense TRICARE beneficiaries from January 2005 through December 2010. Medical record databases were used to identify and classify all annual first-positive S. aureus blood and wound or abscess cultures as methicillin-susceptible S. aureus or MRSA, and as community-onset or hospital-onset infections (isolates collected >3 days after hospital admission).

Main outcome measures: Unadjusted incidence rates per 100,000 person-years of observation, the proportion of infections that was due to MRSA, and annual trends for 2005 through 2010 (examined using the Spearman rank correlation test or the Mantel-Haenszel χ2 test for linear trend).

Results: During 56 million person-years (nonactive duty: 47 million person-years; active duty: 9 million person-years), there were 2643 blood and 80,281 wound or abscess annual first-positive S. aureus cultures. Annual incidence rates varied from 3.6 to 6.0 per 100,000 person-years for S. aureus bacteremia and 122.7 to 168.9 per 100,000 person-years for S. aureus SSTIs. The annual incidence rates for community-onset MRSA bacteremia decreased from 1.7 per 100,000 person-years (95% CI, 1.5-2.0 per 100,000 person-years) in 2005 to 1.2 per 100,000 person-years (95% CI, 0.9-1.4 per 100,000 person-years) in 2010 (P = .005 for trend). The annual incidence rates for hospital-onset MRSA bacteremia also decreased from 0.7 per 100,000 person-years (95% CI, 0.6-0.9 per 100,000 person-years) in 2005 to 0.4 per 100,000 person-years (95% CI, 0.3-0.5 per 100,000 person-years) in 2010 (P = .005 for trend). Concurrently, the proportion of community-onset SSTI due to MRSA peaked at 62% in 2006 before decreasing annually to 52% in 2010 (P < .001 for trend).

Conclusion: In the Department of Defense population consisting of men and women of all ages from across the United States, the rates of both community-onset and hospital-onset MRSA bacteremia decreased in parallel, while the proportion of community-onset SSTIs due to MRSA has more recently declined.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Bacteremia / epidemiology*
  • Child
  • Child, Preschool
  • Community-Acquired Infections / epidemiology
  • Cross Infection / epidemiology
  • Databases, Factual
  • Female
  • Humans
  • Incidence
  • Male
  • Methicillin-Resistant Staphylococcus aureus*
  • Middle Aged
  • Military Personnel / statistics & numerical data*
  • Retrospective Studies
  • Soft Tissue Infections / epidemiology*
  • Staphylococcal Infections / epidemiology*
  • Staphylococcal Skin Infections / epidemiology*
  • United States / epidemiology
  • Young Adult