Most common contributory factor to respiratory failure in patients with cystic fibrosis is:

P. aeruginosa is the most common cause of gram-negative bacteremia in neutropenic patients and it is the most common contributing factor to respiratory failure in cystic fibrosis and is responsible for the majority of deaths among them. P. aeruginosa infection in burns is no longer a major problem. Ref: Harrison, E-18, P-1266.