[Bacteriological and clinical studies in 23 cases of thoracic empyema--the role of oral streptococci and anaerobes].

The bacteriology of empyema fluid and the clinical background of 23 cases from July 1987 through July 1992 were studied. Nineteen cases were male and 4 female, with a mean age of 59.6 years (range; 33 to 84 y.o.). There were 15 cases of community-acquired infection and 8 of nosocomial infection. Acute pneumonia and/or lung abscess developed into empyema in 19 cases. Sixteen cases had associated predisposing conditions, such as diabetes, chronic bronchitis, disorders with dysphagia, and excess alcohol intake. Forty-one strains were isolated from empyema in 22 cases. The predominant organisms, in order of prevalence, were "Streptococcus milleri" group (11 strains), Peptostreptococcus spp. (6), Prevotella spp. (6), Fusobacterium spp. (5) and other viridans streptococci (3). The majority of streptococcal infections, which were primarily caused by "S. milleri" group, were mixed with anaerobes and/or aerobes/facultatives. These results demonstrate that oral streptococci, especially "S. milleri" group, and anaerobes play a significant role as pathogens in empyema.