Methicillin-Resistant Staphylococcus aureus Colonization and Empyema: Does it Matter?

Background: The relation between MRSA colonization and empyema culture results is unknown. We hypothesized that MRSA-colonized patients would be more likely to develop MRSA empyema, and sought to determine if MRSA culture positive empyema had an effect on clinical management or patient outcomes. Methods: The medical records of patients with a diagnosis of empyema from 2007-2010 were retrospectively reviewed for demographics, MRSA colonization status, comorbidities, culture results, clinical management, and discharge disposition. The relationship between MRSA colonization status and culture results was analyzed by bivariate testing. Logistic regression was utilized to determine relations between empyema culture results, comorbidities, and clinical course. Results: Of 147 patients identified with empyema, 16 (10.8%) were MRSA colonized. Colonized patients had substantially higher rates of MRSA-positive empyema cultures (75% vs. 4.6%; p<0.001). A greater percentage of the MRSA-positive empyema patients 66.7% were managed with tube thoracostomy alone, compared with culture positive patients with an organism other than MRSA and those with negative cultures (39% and 34% respectively; p=0.043). Neither empyema culture results nor colonization status were substantial risk factors for poor discharge (skilled nursing facility, long-term care hospital, or death). Conclusions: MRSA-colonized patients hospitalized with empyema are highly likely to have cultures positive for MRSA.