Using active methicillin-resistant Staphylococcus aureus surveillance nasal swabs to predict clinical respiratory...

Results of a study to determine the utility of methicillin-resistant Staphylococcus aureus (MRSA) active surveillance via nasal-swab screening in predicting the results of clinical respiratory cultures are reported.

A retrospective chart review-based descriptive analysis was conducted at a Veterans Affairs (VA) medical center. VA databases were used to identify adult patients admitted to the facility over a one-year period who underwent both respiratory culture testing and active MRSA surveillance nasal-swab screening during the hospitalization; only data on patients who had a MRSA surveillance swab within 48 hours before or after respiratory culture testing were included in the analysis. The sensitivity, specificity, and positive and negative predictive values of the MRSA screening method were calculated.

Data on a total of 297 respiratory cultures and corresponding nasal-swab results were reviewed. The positive predictive value of the nasal-swab method of MRSA surveillance screening was calculated as 37.5% (95% confidence interval [CI], 21.1-56.3%); the negative predictive value was 99.3% (95% CI, 97.3-99.9%). MRSA screening by nasal swab had a calculated specificity of 92.9% (95% CI, 89.3-95.6%) and sensitivity of 87.5% (95% CI, 57.2-98.2%). Using Fisher's exact test, it was determined that there was a significant association between swab and culture results (p < 0.001).

This analysis demonstrated a notable association between negative results of nasal-swab screening for MRSA and an absence of MRSA growth on respiratory clinical cultures at the study site, suggesting that airway swab screening can be a useful tool for streamlining antimicrobial therapy.