Reduction of the spread of nosocomial and community‐acquired methicillin‐resistant Staphylococcus aureus (MRSA) has become a health priority for hospitals and public health officials because of the increasing rate of MRSA infections and the difficulty in treating these severe infections. Efforts to address the increasing trend of MRSA cases involve routine prevention practices, including active surveillance programs that screen for MRSA. Within the intensive care unit (ICU) at the University of New Mexico Hospital, screening for MRSA colonization by nasal swab has been implemented since June 2008 in an effort to control the nosocomial spread of MRSA. The goal of this study was to analyze positive MRSA nasal screenings at admission to the ICU as a predictor for developing MRSA ventilator‐associated pneumonia (VAP).
We performed a retrospective chart review of all adult patients with VAP in the ICU of a university‐affiliated hospital over 4 years (June 2008 through May 2012). Patients met criteria for the study if they had confirmed VAP and a nasal MRSA colonization screening test performed on admission to the ICU. The etiologic agent of VAP was assumed to be MRSA if endotracheal sputum or blood grew MRSA (MRSA‐positive VAP).
Of the 56 patients who met inclusion criteria, 6 (11%) had MRSA‐positive VAP. Of the patients who developed MRSA‐positive VAP, 50% had positive nasal screens at admission, whereas only 1 of 50 patients (2%) with non‐MRSA VAP screened positive at admission. The sensitivity and specificity of an MRSA‐positive screening at admission to the ICU for MRSA‐positive VAP were 50% and 98%, respectively. The positive predictive value of developing a MRSA‐positive VAP with a positive nasal swab was 75%. The negative predictive value of developing a MRSA VAP with a negative swab was 94%.
In this single‐site ICU study, patients with a negative MRSA nasal swab on admission were very unlikely to develop a MRSA‐positive VAP. MRSA screening may be useful as a guide to empiric antibiotic therapy for patients developing VAP.