Pseudomonas cepacia-associated pneumonia in cystic fibrosis. Relation of clinical features to histopathologic patterns of pneumonia.

We studied lungs at autopsy from 40 patients with cystic fibrosis (CF) to determine the structural and clinicopathologic features of pneumonia associated with Pseudomonas cepacia respiratory tract colonization. Three clinical groups were identified: group A included 11 patients exhibiting a fulminant course following P cepacia colonization; group B included 20 patients who declined slowly following colonization; and group C included nine patients without P cepacia colonization. Acute pneumonia occurred in all groups but was most extensive and necrotizing in group A. Chronic lobular pneumonia involved all groups equally, whereas interstitial pneumonia predominated in group B. Diffuse alveolar damage occurred infrequently in all groups. Combinations of structural patterns were frequently seen. We conclude that, although there is great overlap in the structural appearance of pneumonia among patients with CF with different bacterial colonization histories, the evidence suggests that P cepacia is a cause of necrotizing pneumonia in some patients. Factors that predispose to this fulminant lung infection are poorly understood.