EPIDEMIOLOGY OF CHRONIC PSEUDOMONAS-AERUGINOSA INFECTIONS IN CYSTIC-FIBROSIS

The epidemiology of chronic colonization of airways with Pseudomonas a eruginosa was monitored in 44 patients with cystic fibrosis (CF) by Dr aI/SpeI macrorestriction analyses of 489 isolates. Sequential P. aerug inosa isolates (144) that had been collected from 32 CF patients over less than or equal to 2.5 years were investigated, and 12 patients wer e followed for 8 years after onset of colonization. Forty-eight differ ent genotypes were uncovered from 481 typeable isolates. Ten genotypes were found in >1 unrelated CF patient. The 6 most frequent clones wer e identified in 58% of isolates. Ten of the 12 patients monitored for 8 years were harboring their initially acquired P. aeruginosa done at all times, with subtle shifts of fragment patterns indicating subclona l variation. During colonization, the bacteria gradually lost pyocin a nd phage typing responses, supporting the view that genotypically disc ordant P. aeruginosa strains develop a common phenotype.