Representational Difference Analysis used to identify specific genomic regions in Escherichia coli strains responsible for neonatal meningitis.

Objective - Among the previously described virulence factors of Escherichia coil causing neonatal meningitis (KI capsular polysaccharide, aerobactin, S-fimbriae, and the Ibe10 protein) none are sufficient to account in totali ty for the pathogenesis of this bacteria. Pathogenicity islands (PAI) have been described in strains of E. coli responsible for urinary tract infectio n and diarrhea. Material and methods - To identify such regions, specific for neonatal meni ngitis, we used a representational difference analysis to subtract the geno mes of 2 strains belonging to the non-pathogenic phylogenetic group A of th e ECOR reference collection from a neonatal meningitis-causing strain, E. c oli C5. This strain belongs to the phylogenetic group B2 as do most E. coli strains responsible for neonatal meningitis. Results - Sixty-five DNA fragments specific to strain C5, not found in non- pathogenic strains, were mapped on the chromosome. Forty-four of these frag ments were clustered in six different regions. The sfa gene was located in region 2, while a group of genes (cnfl, hra, hly, prs) associated in a PAI of the J96 uropathogenic strain were located in region 6 along with the Ibe 10 gene. Regions 1, 3, and 4 were significantly highly represented in menin gitis strains, compared to control E. coli from group B2. This data suggest s that these three regions identified code specifically for factors associa ted with the ability of E. coli to cause neonatal meningitis. (C) 2000 Edit ions scientifiques et medicales Elsevier SAS.