RISK FACTORS FOR COMMUNITY-ASSOCIATED METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS PNEUMONIA AND OUTCOMES

Abstract

PURPOSE: Clinical presentation of community associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) pneumonia is often indistinguishable from other causes of community acquired pneumonia (CAP). The utility of previously described risk factors to identify MRSA pneumonia remains unknown. We performed a review of hospitalized patients with MRSA pneumonia to determine the proportion of patients with known risk factors for MRSA and their clinical outcome. METHODS: We conducted a retrospective review of patients diagnosed with MRSA pneumonia in a tertiary academic hospital from 12/01/2007 to 9/1/2008. We excluded patients younger than 18 years of age, and those with pneumonia secondary to primary bacteremia. Cases were separated into CAP and health-care associated pneumonia (HCAP) as previously described. Demographic information, known risk factors for MRSA and data on process of care and clinical outcomes was obtained from the medical record. Appropriate dosages of vancomycin or linezolid were considered appropriate antimicrobials. Data is presented as proportions and non-parametric tests were used as appropriate for the analysis. RESULTS: Twenty-eight patients with MRSA pneumonia were identified. 9 (32%) had CAP. Table1 exhibits the baseline demographics of the cohort, and percent with CA-MRSA pneumonia. Two-third of the patients with CA-MRSA had no identifiable risk factor. Patients with CA-MRSA were more likely to have delay in appropriate antibiotics (9.75hrs vs. 6.2hrs), higher pulmonary complication rates (44.4% vs. 26.3%) and longer length of stay (19 days vs. 17.5 days). However, the mortality was similar to HCAP-MRSA. CONCLUSION: Previously known risk factors may not be sufficient to identify patients presenting with CA-MRSA pneumonia, and may cause delay in appropriate antimicrobial administration. CLINICAL IMPLICATIONS: Further studies are needed to clarify the risk factors for CA-MRSA pneumonia.