EXCHANGE OF PSEUDOMONAS-AERUGINOSA STRAINS AMONG CYSTIC-FIBROSIS SIBLINGS

The molecular epidemiology of Pseudomonas aeroginosa infection in cyst ic fibrosis (CF) siblings was analysed by DNA fingerprinting using arb itrary primed polymerase chain reaction, A total of 306 strains collec ted from six pairs of siblings over a period of 20-126 months (median 64) was studied, Fifty-four different P. aeruginosa genotypes were rec ognized. Two out of six pairs of siblings were ultimately colonized by identical strains, and it was shown that a single P. aeruginosa clone can persist in an individual patient for over ten years. No overlap i n P. aeroginosa genotypes was encountered between families, whereas in all families at least transient cross-colonization with the same geno type was observed. This finding demonstrates that P. aeruginosa cross- infection or acquisition of the same strain from an identical environm ental source exists within the family situation, but does not always r esult in a long-term colonization by identical genotypes in all family members suffering from CF.