Progression of pulmonary disease after disappearance of Pseudomonas in cystic fibrosis.

Once cystic fibrosis (CF) patients become chronically colonized, eradication of Pseudomonas aeruginosa (PA) is rare. We report five patients, each colonized for at least 6 yr, whose subsequent cultures did not reveal PA or any other gram-negative pathogen for at least 2 yr. Two patients harbored yeast, normal throat flora, and occasional colonies of Aspergillus fumigatus, but no PA, Haemophilus influenzae, or other gram-negative pathogens. In two patients, sputum cultures revealed Staphylococcus aureus. Sputum smear showed no gram-negative organisms in any patient. Antipseudomonal antibody titers in all patients decreased during the noncolonized period. However, titers increased in four other CF patients who had continued PA colonization. Despite disappearance of PA, four of five patients had clinical progression of lung disease with deterioration of FEV1. We conclude that (1) PA, even after it has chronically colonized the airways of CF patients, can occasionally disappear; and (2) lung disease can progress despite the disappearance of PA. Thus, the elimination of a milieu favorable to PA, such as might be anticipated with therapy directed at the basic defect, may not be sufficient to halt the pulmonary disease progression in CF.