Rapid diagnosis of anaerobic empyema by direct gas-liquid chromatography of pleural fluid.

Sixty samples of pleural fluid from 52 patients were subjected to direct gas-liquid chromatographic studies, and results were correlated with findings from microbiologic cultures. Fourteen patients had anaerobic empyema, 22 had aerobic infections, and 16 had sterile pleural effusions. Multiple volatile fatty acids or succinic acid or both were found as markers of anaerobic infection in all but one instance. Aerobic infections and sterile pleural fluids were characterized by the absence of multiple volatile fatty acids or succinic acid. Infection with Bacteroides, when present, was characterized by a major product of succinic acid. One patient infected with Peptococcus magnus (which does not produce fatty acids or succinic acid) could not be diagnosed by gas-liquid chromatograms. Two patients without anaerobic bacteria in the pleural effusions but who had infections associated with Bacteroides fragilis outside the pleural space demonstrated succinic acid in the pleural fluid. With these exceptions, the presence of volatile fatty acids or succinic acid in pleural fluid was considered characteristic of anaerobic empyema. Direct gas-liquid chromatographic study of pleural fluids is, therefore, recommended as a routine procedure for rapid diagnosis of anaerobic empyema.