Capsulated Haemophilus influenzae and bronchiectasis

Thirty-four patients with bronchiectasis were studied for periods of up to 5 yr in an attempt to determine the part played by capsulated strains of Haemophilus influenzae in this disease and the consequent likelihood that type-specific immunisation against such strains would be beneficial. Capsulated haemophili were isolated from sputum from only 5 of the 34 patients and fourfold or greater rises of capsular antibody were observed in only 10 of 33 of the patients who were subjected to repeated serological examinations. These findings indicate that infection of the patients' respiratory tracts with capsulated strains was not unduly common during the period of the study. The patients as a group did not differ significantly in their serum titres of haemophilus capsular antibody from control groups of subjects without lower respiratory tract disease, and therefore had almost certainly not had a greater than usual experience of capsulated haemophili. These findings are in sharp contrast to the existing evidence about the role of the species H. influenzae in chronic bronchial disease, and appear to indicate that capsulated haemophilus strains differ from non-capsulated strains in playing no part in bronchiectasis.