The risk of infection after nasal colonization with Staphylococcus aureus

Am J Med. 2008 Apr;121(4):310-5. doi: 10.1016/j.amjmed.2007.07.034.


Purpose: Nasal, axillary, or inguinal colonization with Staphylococcus aureus generally precedes invasive infection. Some studies have found that colonization with methicillin-resistant S. aureus (MRSA) poses a greater risk of clinical infection than colonization with methicillin-susceptible S. aureus (MSSA). However, the magnitude of risk is unclear.

Methods: We undertook a systematic review to provide an overall estimate of the risk of infection following colonization with MRSA compared with colonization by MSSA. Ten observational studies, with a total of 1170 patients, were identified that provided data on both MSSA and MRSA colonization and infection. A random-effects model was used to obtain pooled estimates of the odds ratio and 95% confidence interval.

Results: Overall, colonization by MRSA was associated with a 4-fold increase in the risk of infection (odds ratio 4.08, 95% confidence interval, 2.10-7.44). Studies differed in the choice of patient population, severity of illness, and frequency of sampling to detect colonization.

Conclusion: Further research is needed to identify effective methods for sustained eradication of MRSA carriage to reduce the high risk of subsequent infection.

Publication types

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

MeSH terms

  • Cohort Studies
  • Colony Count, Microbial
  • Confidence Intervals
  • Female
  • Humans
  • Incidence
  • Male
  • Meta-Analysis as Topic
  • Methicillin Resistance*
  • Microbial Sensitivity Tests
  • Nasal Cavity / microbiology*
  • Nasal Mucosa / microbiology
  • Odds Ratio
  • Predictive Value of Tests
  • Risk Factors
  • Sensitivity and Specificity
  • Severity of Illness Index
  • Staphylococcal Infections / diagnosis
  • Staphylococcal Infections / epidemiology*
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / isolation & purification*