P aeruginosa-free survival curves analyzed by center for screened and control CF patients using information either from all respiratory secretion cultures (A) or from specimens taken at 6-month intervals (B) as specified in our evaluation and treatment prot... P aeruginosa-free survival curves analyzed by center for screened and control CF patients using information either from all respiratory secretion cultures (A) or from specimens taken at 6-month intervals (B) as specified in our evaluation and treatment protocol. Philip M. Farrell et al. Pediatrics 1997;100:e2 ©1997 by American Academy of Pediatrics