Etiologic diagnosis of intrapleural empyema by counterimmunoelectrophoresis.

Cultural methods failed to identify the infecting organism in 4 patients with intrapleural empyema. Antimicrobial drugs had been administered to 3 of the patients before their admssion to the hospital. In each case, soluble polysaccharides believed to be those of pneumococcus or hemophilus were detected in the empyema fluid by counterimmunoelectrophoresis. These findings provided a rational basis for management of antimicrobial therapy for 3 of the patients and useful information on the origins of the empyema in the fourth patient. Counterimmunoelectrophoresis is a useful additional method for presumptively identifying the infecting organism in patients with intrapleural empyema.