A 30-month experience of thoracic empyema in a tertiary hospital: Emphasis on differing bacteriology and outcome between the medical intensive care unit (MICU) and medical ward

Objectives: To analyze the causative pathogens and outcomes of patients with thoracic empyema admitted to the medical intensive care unit (MICU) and medical ward. Methods: We prospectively studied the empyemic patients in the MICU and retrospectively analyzed the medical records of empyemic patients in the medical ward treated in a tertiary university hospital from April 2001 to September 2003. Results: During this period, 116 patients in the medical ward and 78 patients in MICU had complicated parapneumonic effusions or empyemas. Effusion cultures were positive in 164 patients (85%); a total of 147 and 78 microorganisms were isolated from the 106 medical ward patients and 58 MICU patients, respectively. No matter whether medical ward or MICU patients, aerobic Gram-negative organisms were the most common bacteria in positive-culture effusions (110, 67%). Klebsiella pneumoniae (14, 24%) was the predominant pathogen among the MICU patients, and Streptococcus spp. (28, 26%) was the main pathogen among the medical ward patients. Compared with these positive-culture empyemic patients in the medical ward, MICU patients had a significantly higher percentage of aerobic Gram-negative organism infections (P = 0.034) and a higher infection-related mortality rate (P = 0.01). Conclusion: The mortality and predominant pathogens in patients with complicated parapneumonic effusions or thoracic empyemas in the medical ward and MICU were different. The increasing Gram-negative pathogens in empyemas have become an urgent problem.