Hybrid strains of
Escherichia coli combine
virulence traits of diarrheagenic (DEC) and
extraintestinal pathogenic E. coli (
ExPEC), but it is poorly understood whether these combined features improve the
virulence potential of such
strains. We have previously identified a
uropathogenic E. coli (UPEC)
strain (UPEC 252) harboring the eae
gene that encodes the adhesin intimin and is located in the locus of
enterocyte effacement (LEE)
pathogenicity island. The LEE-encoded
proteins allow
enteropathogenic E. coli (
EPEC) and
enterohemorrhagic E. coli (
EHEC) to form attaching and effacing (A/E) lesions in
enterocytes. We sought to characterize UPEC 252 through whole-
genome sequencing and phenotypic
virulence assays.
Genome analysis unveiled that this
strain harbors a complete LEE region, with more than 97% of identity comparing to E2348/69 (
EPEC) and O157H7 Sakai (
EHEC) prototype
strains, which was functional, since UPEC 252 expressed the LEE-encoded
proteins EspB and intimin and induced
actin accumulation foci in
HeLa cells.
Phylogenetic analysis performed comparing 1,000 single-copy
shared genes clustered UPEC 252 with atypical
EPEC strains that belong to the sequence type 10, phylogroup A. Additionally, UPEC 252 was resistant to the bactericidal
power of
human serum and colonized
cells of the urinary (T24 and HEK293-T) and intestinal (Caco-2 and LS174T) tracts. Our findings suggest that UPEC 252 is an atypical
EPEC strain that emerges as a
hybrid strain (aEPEC/UPEC), which could colonize new niches and potentially cause intestinal and extraintestinal
infections.