Evolution of airway microbiology in the infant with cystic fibrosis: role of nonpseudomonal and pseudomonal pathogens.

Bacterial colonization of the airways of the infant with cystic fibrosis is usually established early in life, and, once established, is difficult to eradicate and is associated with progressive lung disease. Thus, understanding of early airway microbiology is critical to the development of appropriate early interventions such as prophylactic antibiotics, immunotherapy, and, potentially, gene therapy. The barriers to the study of infant airway microbiology are discussed, and the properties of infant lung anatomy, physiology, and immunity, which predispose the young patient to serious infection, are reviewed. We examine the natural history of lung infection in young patients, reviewing the roles of each of the main bacterial pathogens. Recent research on risk factors for early Pseudomonas aeruginosa colonization, including the potential role of respiratory viral infections, is discussed. We conclude with a discussion of the role of prophylactic antibiotic therapy.