Session: Poster Session: Gram-Positive VAP/HAP
Saturday, October 25, 2008: 12:00 AM
Room: Hall C
Background: Methicillin-resistant Staphylococcus aureus (S. aureus [SA]) (MRSA) pneumonia is a major cause of hospital-acquired pneumonia in the US. The importance of MRSA in healthcare-associated pneumonia (HCAP) remains unclear, however. We address this issue in this study. Methods: We retrospectively identified all patients with SA HCAP admitted to a large US urban teaching hospital between January 2005 and December 2007, based on a discharge diagnosis of pneumonia and (all within 48h of admission): (1) positive SA culture (blood or sputum); (2) positive chest X-ray; (3) signs/symptoms of pneumonia; and (4) history of recent hospitalization, hemodialysis, chemotherapy, or other established criteria for HCAP. Patients were designated as having MRSA or methicillin-susceptible SA (MSSA) based on initial culture results. Results: A total of 128 patients with SA HCAP were identified. Mean (SD) age was 64 (17) years; 82 patients (64%) were nonwhite. Prevalence of diabetes, cancer, chronic renal failure, coronary artery disease, heart failure, peripheral vascular disease, and chronic respiratory disease was high (all >20%). Seventy-eight patients (61%) had positive MRSA cultures; USA-300 accounted for 15% of MRSA strains. Only 7 MRSA patients (9%) had vancomycin MIC values <1 mcg/ml by E-test. Patients with MRSA were more likely to have had a positive MRSA culture in the year prior to admission (19 [24%] vs 2 [4%] for MSSA patients; p=.003), and to have received antibiotics in the month prior to admission (20 [40%] vs 46 [59%] respectively; p=.046). Conclusion: More than one-half of patients with SA HCAP have MRSA; prior MRSA culture and recent (<30d) exposure to antibiotics are common findings in these patients.