A RETROSPECTIVE REVIEW OF CASES OF ANAEROBIC EMPYEMA AND UPDATE OF BACTERIOLOGY

We conducted a retrospective study to update the bacteriology of 46 ca ses of anaerobic empyema that were originally studied between 1976 and 1993 at the Wadsworth Anaerobic Bacteriology Clinical Research Labora tory (Los Angeles), Anaerobic bacteriologic studies were completed for all 46 pleural fluid specimens, and aerobic bacteriologic studies wer e completed for 41 of these specimens. Thirty-seven clinical charts we re available for review, A total of 161 anaerobic isolates (3.5 per pa tient) representing 64 species or groups were recovered, The most comm on isolates were as follows: Fusobacterium nucleatum (19); Prevotella oris-buccae group (13, 9 of which were P. oris); Bacteroides fragilis group (11, 4 of which were B. fragilis); pigmented Prevotella species (17, 8 of which were in the Prevotella intermedia-nigrescens group); P eptostreptococcus species (17, 9 of which were Peptostreptococcus micr os); Eubacterium species (7); Lactobacillus species (8); Actinomyces s pecies (7); and Clostridium species (7). Nineteen of the cases were of purely anaerobic etiology; of these, eight were caused by a single or ganism: F. nucleatum (five cases); B. fragilis (two cases); and Prevot ella magnus (one case), Of the 45 aerobic isolates (1,1 per patient), viridans streptococci were most common (21 isolates), followed by grou p D nonenterococcal streptococci (four isolates). Only nine gram-negat ive rods (six enteric and three nonenteric organisms) and one Staphylo coccus aureus isolate were recovered, The susceptibility to penicillin of 64 isolates was examined with use of the spiral gradient method; 2 1 (33%) of these isolates were beta-lactamase positive (MICs ranged fr om 1.1 to greater than or equal to 54 mu g/mL vs. less than or equal t o 0.27 mu g/mL for beta-lactamase-negative strains).