An improved test for Haemophilus influenzae precipitins in the serum of patients with chronic respiratory disease.

The detection of antibacterial precipitins in the serum of patients with chronic lower respiratory infections has been shown to be of great value in the assessment of pathogenicity of the corresponding bacterial species in the sputum. The test used hitherto, however, is time-consuming and cumbersome owing to the need to distinguish, by immunoelectrophoresis, between antibodies specific to the organism in question and those which react with antigens common to various Gram-negative species. A method has now been devised for the preparation of an extract of Haemophilus influenzae containing species-specific antigens only. Use of this extract obviates the need for immuno-electrophoresis and improves the sensitivity of the test.