Spp. Bonacorsi et al., Identification of regions of the Escherichia coli chromosome specific for neonatal meningitis-associated strains, INFEC IMMUN, 68(4), 2000, pp. 2096-2101
Specific virulence factors associated with the pathogenesis of Escherichia
coli strains causing neonatal meningitis (ECNM), such as the K1 capsular po
lysaccharide, the S fimbriae, and the Ibe10 protein, have been previously i
dentified. However, some other yet unidentified factors are likely to be in
volved in the pathogenesis of ECNM. To identify specialized unique DNA regi
ons associated with ECNM virulence, we used the representational difference
analysis technique. The genomes of two strains belonging to nonpathogenic
phylogenetic group A of the ECOR reference collection were subtracted from
E. coli strain C5, isolated from a case of neonatal meningitis. Strain C5 b
elongs to the phylogenetic group B2 as do the majority of ECNM, We have iso
lated and mapped 64 DNA fragments which are specific for strain C5 and not
found in nonpathogenic strains. Of these clones, 44 were clustered in six d
istinct regions on the chromosome. The sfa and ibe10 genes were located in
regions 2 and 6, respectively, A group of genes (cnf1, hra, hly, and prs) k
nown to be present in a pathogenicity island of the uropathogenic strain E.
coli J96 colocalized with region 6. The occurrence of these DNA regions wa
s tested in a set of meningitis-associated strains and in a central group c
omposed of non-meningitis-associated strains belonging to the same B2 group
. Regions 1, 3, and 4 were present in 91, 82, and 81%, respectively, of the
meningitis strains and in 40, 13, and 47% of the control strains. Together
, these data suggest that regions 1, 3, and 4 code for factors associated w
ith the ability of E. coli to invade the meninges of neonates.