Cystic Fibrosis



  • Defect of the cystic fibrosis transmembrane conductance regulator (CFTR)
  • CFTR functions as an ATP-regulated chloride channel that regulates the activity of chloride and sodium channels on the cell surface:
    • Abnormal electrolyte transport in exocrine glands and secretory epithelia
    • Decreased exocrine pancreatic function with malabsorption
    • Thickened mucus, recurrent pulmonary infections, and progressive obstructive damage to the lungs
    • Recurrent sinus disease
  • Occurs in 1:3,600 live births in White population, 1:29,000 in African American population; 1:6,500 in Hispanic population
  • 30% of cases diagnosed by newborn screening
  • 75% cases diagnosed in the first 2 yr of life
  • ∼30,000 children and young adults in the U.S. have CF
  • Median life expectancy in the U.S. in early 40’s
  • 40% of CF patients are >18 yr
  • 10 million Americans are unknown, asymptomatic carriers of the defective gene
  • 16% of lung transplants in the U.S. due to CF

Risk Factors

Recessively inherited genetic disease, involving the CFTR gene on the long arm of chromosome 7:
  • Different mutations; variable phenotypes
  • Classic disease: Homozygous Phe508del mutation
  • Most common lethal genetic disease in the U.S.


Common organisms in patients with pneumonia; often multiple drug resistance:
  • Staphylococcus aureus:
  • Pseudomonas aeruginosa:
    • Prevalence increases with age; >70% of adults are chronically infected
  • Haemophilus influenzae
  • Stenotrophomonas maltophilia
  • Burkholderia cepacia:
    • Prevalence 3%
    • Associated with rapid clinical deterioration
  • Achromobacter xylosoxidans
  • Mycobacteria (nontuberculous):
    • Mycobacterium avium complex, Mycobacterium abscessus
  • Aspergillus

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