What is the sensitivity of nose swabs in detecting methicillin-resistant Staphylococcus aureus (MRSA) pneumonia?

In MRSA pneumonia, the sensitivity of nasal swab PCR may vary from as low as 24.2% to 88% (1-3). A single center  study involving  patients with possible healthcare-associated pneumonia (HCAP) and a low clinical pulmonary infection score (CPIS) — for whom antibiotics may not be necessary anyway (4)—suggested that discontinuation of empiric vancomycin in patients without an adequate respiratory culture and a negative nose and throat culture may be reasonable (5).  However, a prospective study of ICU patients concluded that “clinicians cannot reliably use the results of initial negative MRSA nasal swab results to withhold empirical MRSA coverage from patients who otherwise are at risk for MRSA infection” (3).

Thus, there is currently insufficient data to support discontinuation of vancomycin based on a negative nasal screen alone, particularly in patients who may be at high risk of MRSA pneumonia.

 

References

  1. Rimawi RH, Ramsey KM, Shah KB, et al. Correlation between methicillin-resistant Staphylococcus aureus nasal sampling, and S. aureus pneumonia in the medical intensive care unit. Infect Control Hosp Epidemiol 2014;35:590-92.
  2. Dangerfield B, Chung A, Webb B, et al. Predictive value of methicillin-resistant Staphylococcus aureus (MRSA) nasal swab PCR assay for MRSA pneumonia. Antimicrob Agents Chemother 2014;58:859-64.
  3. Sarikonda KV, Micek ST, Doherty JA, et al. Methicillin-resistant Staphylococcus aureus nasal colonization is a poor predictor of intensive care unit-acquired methicillin-resistant Staphylococcus aureus infections requiring antibiotic treatment. Crit Care Med 2010;38:1991-1995.
  4. Napolitano LM. Use of severity scoring and stratification factors in clinical trials of hospital-acquired and ventilator-associated pneumonia. Clin Infect Dis 2010;51:S67-S80.
  5. Boyce JM, Pop O-F, Abreu-Lanfranco O, et al. A trial of discontinuation of empiric vancomycin therapy in patients with suspected methicillin-resistant Staphylococcus aureus health care-associated pneumonia. Antimicrob Agents Chemother 2013;57:1163-1168.
What is the sensitivity of nose swabs in detecting methicillin-resistant Staphylococcus aureus (MRSA) pneumonia?

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