The bacterial flora of the respiratory tract of patients with cystic fibrosis was observed from 1950 onwards. Serum precipitins against Staph. aureus, H. influenzae, and Ps. aeruginosa were determined in the serum of 102 patients.
A trend of change in the bacterial flora was noted; the isolation rate of Staph. aureus fell, whether related to age or severity of disease, while after 1964 there was an increased isolation rate of Ps. aeruginosa in the most severely affected patients.
Bacterial precipitins were found in 55 of 102 patients. Generally the presence of these correlated with the radiological changes. Pseudomonas precipitins were found chiefly in patients with generalized changes, while precipitins against staphylococcus and haemophilus occurred more in patients who had either no radiological change or less severe changes.
These findings have relevance to the management of patients with cystic fibrosis. It is suggested that factors other than bacterial infection may initiate the lung changes in children with cystic fibrosis.