Methicillin resistant Staphylococcus aureus (MRSA) ventilator-associated pneumonia (VAP) is increasing in prevalence. Treatment of VAP has moved toward ensuring patients are adequately covered for MRSA and other MDROs while balancing the need for antimicrobial stewardship and appropriateness of empiric coverage of these organisms in the setting of increasing resistance rates. The objective of this study was to identify the incidence of and risk factors for MRSA VAP in surgical intensive care unit (SICU) patients as a means to better identify patients at risk who would benefit from MRSA coverage empirically.
This was a single-center, retrospective risk factor analysis of adult SICU patients, comparing patients with MRSA VAP to those with VAP due to alternative pathogens. Primary outcomes were incidence of MRSA VAP and risk factors associated with MRSA VAP. A multivariable logistic regression model was performed to identify risk factors for MRSA VAP.
Of 140 included patients, MRSA VAP occurred in 31 (22.1%). Fewer patients in the MRSA group were in septic shock (6.5 vs. 23.9%, p = 0.04) or hemodynamically unstable (16.1 vs. 34.9%, p = 0.03) at the time of VAP diagnosis. A lower proportion of MRSA patients had antibiotic exposure prior to VAP (58.1 vs. 78.9%, p = 0.03). Female sex was associated with a 2.3-fold higher risk for MRSA VAP and history of MRSA with a 4.2-fold higher risk, while patients with prior antibiotic exposure were 60% less likely to develop MRSA VAP.
Ventilator-associated pneumonia due to MRSA was common among this SICU cohort. A history of MRSA infection and lack of prior antibiotic exposure may be useful factors to aid in selection of patients appropriate for empiric MRSA therapy. Risk factor analysis may be difficult in this population due inability to control for all patient-specific variables. Future risk factor studies investigating specific MDRO VAPs and the role of dysbiosis are needed to determine the appropriateness of empiric broad-spectrum therapy.