Should Empiric Therapy for Severe Community Acquired Pneumonia Always Include MRSA Coverage

Abstract

PURPOSE: The Infectious Disease Society of America has recently published Clinical Practice Guidelines for treatment of Methicillin-Resistant Staphylococcus Aureus (MRSA) infections. [CID 2011;52(1 February):1-38.] Included is a recommendation to empirically cover MRSA with vancomycin, linezolid or clindamycin for severe Community Acquired Pneumonia (CAP) as defined by: 1) requirement for ICU admission, 2) necrotizing or cavitary infiltrates or 3) empyema. Prevalence of MRSA in the community was evaluated before adopting the IDSA recommendation to empirically cover MRSA in all patients with severe CAP where the only risk factor is ICU admission. METHODS: All MRSA screens hospital-wide during 4th quarter 2006 through 2010 were entered into a database. Routine MRSA screens are performed weekly on all ventilated patients and on anyone admitted from a Long Term Care facility/hospital within 30 days. MRSA screens done within 2 days of admission were also evaluated. RESULTS: Positive MRSA Screens all samples [% positive (n)]: 2006-7: 18.4% (272), 2008: 18.2% (187), 2009: 14.5% (152), 2010: 15.1% (93). Positive MRSA Screens within two days [% positive (n)] 2006-7: 19.8% (197), 2008: 20.8% (130), 2009: 16.8% (119), 2010: 16.4% (73). There was no statistically significant change in MRSA rates over the years studied. The vast majority of positive screens were health-care related. CONCLUSIONS: Based on local data there has not been an increase in recent years in the prevalence of MRSA in the community served by Crouse Hospital. From this retrospective evaluation, empiric MRSA coverage for patients with severe CAP where ICU admission is the only risk factor is not necessary at our institution. At this time for us the risk of resistance and toxicity from empiric MRSA treatment would does not seem to be justified. All patients are now being prospectively screened for MRSA on admission to the ICU to identify CAP patients needing MRSA treatment and to better evaluate MRSA prevalence in the community. CLINICAL IMPLICATIONS: National Guidelines are essential but final decisions about antimicrobial prescribing practices should be driven by local microbial resistance patterns.