The patterns of infection in cystic fibrosis.

Thirty-five patients with cystic fibrosis (aged 11 months to 13.5 years) have 
been investigated with regard to respiratory symptoms, respiratory tract pathogens, serum 
immunoglobulins and serum precipitins. Haemophilus influenzae was the commonest pathogen being 
supplanted in advanced disease by Pseudomonas aeruginosa. The patients who had 
no respiratory infection had levels of IgG significantly lower than normal 
children of comparable ages. In children with severe respiratory infection the 
immunoglobulins were raised and precipitins to the predominant respiratory organism were 
present. These findings differ from the prevalent view that patients with 
cystic fibrosis have a normal response to infection and that the 
common infecting organism is Staphylococcus aureus. 