Clinical characteristics and outcomes of patients with community-acquired, health-care-associated and hospital-acquired empyema

Patients with pneumonia, a common cause of empyema, are stratified based on their risk factors, and the treatment of empyema might benefit from this risk stratification.The etiology, bacteriologic profile and outcome of patients diagnosed with empyema in Shinko Hospital between May 2005 and October 2013 were retrospectively studied. The patients were stratified according to whether they had community-acquired empyema (CAE), health-care-associated empyema (HCAE) or hospital-acquired empyema (HAE).The study included 81 patients, 25 CAE, 40 HCAE and 16 HAE. The comorbidity rate was highest among HAE patients (100%), followed by 95% of HCAE and 72% of CAE patients (P = 0.005). The rates of cancer and central nervous system (CNS) disease were higher in patients with HCAE and HAE than in patients with CAE (P = 0.030, P = 0.018, respectively). Pleural fluid cultures were positive in 58/81 patients. Streptococcus species were the most common organisms cultured from CAE (12/15) and HCAE patients (17/30), but not from HAE patients (3/13). Anaerobic organisms were cultured from 3 CAE, 5 HCAE and 3 HAE patients. Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa were only cultured from HCAE and HAE patients. The mortality rates were higher in HCAE (18%) and HAE (50%) than in CAE (4%) patients (log-rank test: P = 0.0012).Half of patients with empyema were HCAE patients, who had comorbidities, bacteriological profile and outcome different from CAE patients. The patient with HCAE should be differentiated from CAE patient, and the stratification of patients based on risk factors may be useful for treatment strategy.