Changing ecology of acute bacterial empyema: occurrence and mortality at Boston City Hospital during 12 selected years from 1935 to 1972.

The occurrence, etiology, and demography of acute bacterial empyema are presented to reflect the widespread use of sulfonamides, penicillin, and other active antibiotics. In community-acquired (C-A) cases Streptococcus pneumoniae, hemolytic streptococci, and Staphylococcus aureus were the most frequent single organisms identified in initial positive cultures of pleural fluid during 1935. S. pneumoniae declined steadily until 1953 but continued to occur frequently in C-A cases. Hemolytic streptococci became infrequent. S. aureus increased and became the most frequent organism in 1955 and declined to original levels after 1965 while gram-negative rods increased. S. aureus, aerobic gram-negative rods, and enterococci were most frequent in originally mixed infections, hospital-acquired cases, and superinfections. Anaerobes with or without aerobes were mostly seen in C-A cases and did not vary in incidence. Mortality increased with age. Overall mortality was greater during the 10 antibiotic years, associated with a marked decrease in the proportion of patients younger than 50 years and increase in those over 60 years old, and was greater in patients with serious underlying diseases subjected to more complicated surgical procedures.