Longitudinal assessment of Pseudomonas aeruginosa in young children with cystic fibrosis

Pseudomonas aeruginosa lung infection is an important cause of morbidity an d mortality in cystic fibrosis (CF). Longitudinal assessment of the phenoty pic changes in P. aeruginosa isolated from young children with CF is lackin g. This study investigated genotypic and phenotypic changes in P. aeruginos a from oropharynx (OP) and bronchoalveolar lavage fluid (BALF) in a cohort of 40 CF patients during the first 3 years of life; antibody response was a lso examined. A high degree of genotypic variability was identified, and ea ch patient had unique genotypes. Early isolates had a phenotype distinct fr om those of usual CF isolates: generally nonmucoid and antibiotic susceptib le. Genotype and phenotype correlated between OP and BALF isolates. As dete rmined by culture, 72.5% of patients demonstrated P. aeruginosa during thei r first 3 years. On the basis of combined culture and serologic results, 97 .5% of patients had evidence of infection by age 3 years, which suggests th at P. aeruginosa infection occurs early in CF and may be intermittent or un detectable by culture.