Hospital-Acquired Thoracic Empyema in Adults: A 5-Year Study

Background: The objective of this study was to assess the etiology, microbiology and outcome of hospital-acquired thoracic empyema (HATE) in adults. Methods: From December 2001 to December 2006, 459 adult patients with a diagnosis of thoracic empyema in a tertiary hospital were screened for HATE. HATE was defined as a new pleural empyema which developed after 48 hours of hospitalization. Results: In total, 56 adult (>= 18 years) patients who were diagnosed with HATE were enrolled in our series, including 35 men (62.5%) and 21 women (37.5%), with ages ranging from 22 to 87 years old (mean = 59). Causes of HATE were classified into two categories: hospital-acquired pneumonia (HAP) related (n = 25) and non-HAP related (n = 3 1). Causes of non-HAP related empyema were comprised of catheter-related infections (n = 20), hepatobiliary tract infections (n = 6), septic emboli (n = 4), and postpneumonectomy (n = 1). Comparing the bacteriology between the two categories, HAP-related empyema had a significantly higher incidence of aerobic Gram-negative organisms (76% vs. 38.7%, P = 0.005), polymicrobial pathogens (40% vs. 9.7%, P = 0.008), and anaerobic pathogens (20% vs. 0%, P = 0.009) than non-HAP related empyema. However, there was no significant difference in mortality rate (60% vs. 52%, P = 0.52) between the two categories. Conclusions: Choice of antibiotic treatment for HATE should be based on the etiology of the pleural infection. In treating HAP-related empyema, antibiotics should cover aerobic Gram-negative, polymicrobial, and anaerobic pathogens.