IbeA (invasion of brain endothelium), which is located on a genomic island
termed GimA, is involved in the pathogenesis of several extraintestinal
pathogenic E. coli (ExPEC) pathotypes, including newborn meningitic E. coli
(NMEC) and avian pathogenic E. coli (APEC). To unravel the phylogeny of GimA
and to investigate its island character, the putative insertion locus of GimA
was determined via Long Range PCR and DNA-DNA hybridization in 410 E. coli
isolates, including APEC, NMEC, uropathogenic (UPEC), septicemia-associated E.
coli (SEPEC), and human and animal fecal isolates as well as in 72 strains of
the E. coli reference (ECOR) collection. In addition to a complete GimA (~20.3
kb) and a locus lacking GimA we found a third pattern containing a 342 bp
remnant of GimA in this strain collection. The presence of GimA was almost
exclusively detected in strains belonging to phylogenetic group B2. In
addition, the complete GimA was significantly more frequent in APEC and NMEC
strains while the GimA remnant showed a higher association with UPEC strains.
A detailed analysis of the ibeA sequences revealed the phylogeny of this gene
to be consistent with that obtained by Multi Locus Sequence Typing of the
strains. Although common criteria for genomic islands are partially fulfilled,
GimA rather seems to be an ancestral part of phylogenetic group B2, and it
would therefore be more appropriate to term this genomic region GimA locus
instead of genomic island. The existence of two other patterns reflects a
genomic rearrangement in a reductive evolution-like manner
