Microbiology of empyema in children and adolescents.

The microbiology of empyema was studied in 72 children and adolescents whose specimens yielded bacterial growth after inoculation for aerobic and anaerobic bacteria. A total of 93 organisms, 60 aerobic or facultative and 33 anaerobic, were isolated. Aerobic bacteria was isolated in 48 (67%) patients, anaerobic bacteria in 17 (24%), and mixed aerobic and anaerobic bacteria in 7 (10%). The predominant aerobic or facultative bacteria were Haemophilus influenzae (15 isolates), Streptococcus pneumoniae (13), and Staphylococcus aureus (10). The predominant anaerobes were Bacteroides sp (15 isolates, including 7 Bacteroides fragilis group and 5 Bacteroides melaninogenicus group), anaerobic cocci (9), and Fusobacterium sp (6). beta-lactamase activity was detected in at least one isolate in 20 (37%) of the 54 tested patients. These included all 8 tested S aureus and 7 B fragilis group, 3 of 10 H influenzae, 2 of 4 B melaninogenicus group, and 1 of 2 Klebsiella pneumoniae. Most cases of S pneumoniae and H influenzae were associated with pneumonia. The recovery of anaerobic bacteria was mostly associated with the concomitant diagnosis of aspiration pneumonia, lung abscess, subdiaphragmatic abscess, and abscesses of dental or oropharyngeal origin. The data highlight the importance of anaerobic bacteria in selected cases of empyema in children and adolescents.