No abstract

SUMMARY The relative significance of the pathogenic bacteria found in the respiratory tract (Hamophilus influenzæ, Streptococcus pneumoniæ, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella) as causes of bronchial infection in the chronic respiratory disorders chronic bronchitis, bronchiectasis, asthma and cystic fibrosis was assessed by detecting specific precipitating antibodies in the serum of affected subjects and comparing their frequency with that in healthy controls. The predominant pathogen in such disorders was found to be H. influenzæ, with Strep. pneumoniæ playing a subsidiary role. In bronchiectasis and cystic fibrosis, Staph. aureus, Ps. aeruginosa and Klebsiella are significant pathogens, but not in chronic bronchitis. The true value of such antibody tests is reinforced by the finding that no patient demonstrated specific antibody to a neisseria extract, Neisseria sp. being generally regarded as non‐pathogenic in the respiratory tract. The known failure of antibody titres against H. influenzæ to alter with infection is discussed, and reasons are given which might explain how this phenomenon can occur when this organism is the cause of the infection.