[Analysis of 98 cases of thoracic empyema]

Ninety-eight cases of empyema thoracis admitted to Juntendo University Hospital between 1979 and 1990 were reviewed. Males accounted for 78 cases and females 20 cases. Thirteen pediatric patients ranged in age from 17 days to 4 years, while the 85 adult cases ranged from 16 to 89 years (mean: 58.4 years). The mortality rate increased with age. Fifty-three cases of community-acquired empyema thoracis consisted of 24 with no underlying disease (including 13 pediatric cases), and 29 with diabetes mellitus, alcoholic liver damage or chronic obstructive bronchopulmonary disease. Forty-five nosocomial empyema cases occurred after chest operation or thoracocentesis, or due to a subdiaphragmatic pathogenic condition or congestive heart failure complicated with aspiration pneumonia. In this series, 63 patients (64.3%) had para- or post-pneumonic empyema. Compared with the community-acquired infection cases, the mortality rate of the nosocomial infection cases was very high. Seventy-eight cases were culture-positive, including 3 positive for Mycobacterium tuberculosis. The remaining 20 cases were culture-negative. In 75 cases of culture-positive pleural fluid, aerobic bacteria were isolated from 31 cases (mortality rate: 22.6%), anaerobes mixed with aerobes from 21 cases (mortality rate: 52.4%), and anaerobes only from 23 cases (mortality rate: 21.7%). Thus, the mortality rate of mixed infected cases was highest. Anaerobes were frequently isolated from the community-acquired empyema cases, and were often found in para- or postpneumonic lesions, including aspiration pneumonia. The most commonly encountered aerobe was Staphylococcus aureus. Among the anaerobes, Bacteroides spp., microaerophilic streptococcus, Peptostreptococcus and Fusobacterium spp. were most common. A single organism was isolated in pure culture from 39 cases. Single organisms isolated from fluids were more frequently aerobes (25) than anaerobes (14). The cases harboring Bacteroides spp. showed the worst outcome, with 11 deaths in 25 such cases.