Abstract
A simple, inexpensive method of counter‐current‐immunoelectrophoresis was used to detect pneumococcal antigens in sputum, serum and pleural fluid. Antigens were detected in sputa from 69% of subjects with pneumococcal pneumonia and there was a good correlation with the certainty of the clinical diagnosis. Serum antigens were found in 12.5% of subjects with either a definite or a presumed diagnosis and in one case from a patient who was not thought to have pneumococcal pneumonia. The pathogenic importance of antigens in the sputa of patients with a history of chronic respiratory disease was uncertain. Counter‐current‐immunoelectrophoresis was more sensitive than routine bacteriological methods for demonstrating the presence of pneumococci in pleural fluids.