Enzyme polymorphism in Pseudomonas aeruginosa strains recovered from cystic fibrosis patients in France

Each of 314 strains of Pseudomonas aeruginosa recovered from 87 French cyst ic fibrosis (CF) patients was typed by multilocus enzyme electrophoresis to investigate the genetic diversity, the relatedness and the molecular epide miology of strains isolated from cases of chronic pulmonary colonization. C omparison of allele profiles at 18 enzyme loci identified 17 electrophoreti c types (ETs). Of the 314 isolates, 290 (92 %) were either ET1 (n = 127) or ET2 (n = 163), which differed only at the shikimate dehydrogenase (SKD) lo cus. The mean genetic diversity (H) was 0.138. These results suggest that t here is cross-colonization between patients and/or that two predominant gro ups of strains are able to colonize French CF patients. Sequential isolates collected from 18 patients during a period of 12-28 months were analysed t o assess genomic variability and its relationship to clinical outcome. Six patients were colonized by a stable strain. For the others, double infectio ns or changes in colonization over time were observed. No relationships wer e detected between the clinical outcome and the persistence of stable isola tes, the emergence of transient superinfecting variants, the presence of mu ltiple ETs or the shift of ET during the monitoring.