Epidemiology of chronic Pseudomonas aeruginosa infections in cystic fibrosis

Chronic lung infection with Pseudomonas aeruginosa is primarily responsible for pulmonary deterioration of cystic fibrosis patients. The purpose of th is study was to type the P. aeruginosa isolates collected sequentially from cystic fibrosis patients, chronically colonized with P. aeruginosa, by ran dom amplified polymorphic DNA fingerprinting-PCR (RAPD-PCR). Sequential P. aeruginosa isolates (n: 130) that had been collected from 20 CF patients ov er at least 9 years were investigated. The isolates were analyzed by RAPD-P CR using two arbitrary primers. Antimicrobial susceptibility testing of all isolates was performed by the disc diffusion method. RAPD-PCR typing demon strated that strains dissimilar in colony morphotype and of different antib iotic susceptibility patterns could be of the same genotype. Some CF patien ts were colonized with a rather constant P. aeruginosa flora, with strains of different phenotypes but of one genotype. However, some patients may be colonized with more than one genotype. The results also demonstrated that t here might be a risk of cross-colonization between CF patients followed-up at the same center.