Nearly all exocrine glands are affected in varying distribution and degree of severity. Evidence suggests that the lungs are normal at birth. The pulmonary lesion is probably initiated by diffuse obstruction in the small airways by abnormally thick mucus secretions. Secondary to obstruction, there is bronchiolitis and mucopurulent plugging of the airways. Early in the course, Staphylococcus aureus is the pathogen most often isolated from respiratory tract secretions, but as the disease progresses, Pseudomonas aeruginosa is most frequently isolated.
Death usually results from a combination of respiratory failure and corpulmonale.
In the newborn period, CF may also be associated with delayed passage of meconium and with the menocium plug syndrome , a transient form of distal intestinal obstruction secondary to 1 or more plugs of inspissated meconium in the anus or colon. In infants without meconium ileus, onset is frequently heralded by a delay in regaining birthweight and inadequate weight gain at 4 to 6 wk of age. It is usually present early in life but may be progressive. Fifty percent of all patients present with pulmonary manifestations usually consisting of chronic cough and wheezing associated with recurrent or chronic pulmonary infections. In families with a previously affected child, mutation analysis can be used for prenatal diagnosis and carrier testing.