Comparison of methicillin-resistant staphylococcus aureus community-acquired and healthcare-associated pneumonia

Purpose: Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as an important cause of not only healthcare-associated pneumonia (HCAP) but also community-acquired pneumonia (CAP). We determined the impact of MRSA on differences in clinical characteristics, courses, and outcomes between CAP and HCAP. Materials and Methods: We conducted a retrospective observational study on 78 adult patients admitted with MRSA pneumonia at a university-affiliated tertiary hospital between January 2008 and December 2011. We compared baseline characteristics, chest radiographs, treatment outcomes, and drug resistance patterns between the CAP and HCAP groups. Results: Of the 78 patients with MRSA pneumonia, 57 (73.1%) were HCAP and 21 (26.9%) were CAP. MRSA infection history in the previous year (29.8% vs. 14.3%, p=0.244) tended to be more common in HCAP than in CAP. Despite similar Pneumonia Severity Index scores (151 in CAP vs. 142 in HCAP), intubation rates (38.1% vs. 17.5%; p=0.072) and intensive care unit admission (42.9% vs. 22.8%; p=0.095) tended to be higher in the CAP group, while 28-day mortality was higher in the HCAP group (14.3% vs. 26.3%; p=0.368), although without statistical significance. All patients showed sensitivity to vancomycin and linezolid; meanwhile, HCAP patients showed greater resistance to gentamicin than CAP patients (58.3% vs. 16.6%; p=0.037). The median total hospital charges were 6899 American dollars for CAP and 5715 American dollars for HCAP (p=0.161). Conclusion: MRSA pneumonia showed significantly differences in baseline characteristics, chest radiographs, treatment outcomes, and medical expenses between HCAP and CAP groups.