4 research outputs found
Phylogenetic and Molecular Analysis of Food-Borne Shiga Toxin-Producing Escherichia coli
Seventy-five food-associated Shiga toxin-producing Escherichia coli (STEC)
strains were analyzed by molecular and phylogenetic methods to describe their
pathogenic potential. The presence of the locus of proteolysis activity (LPA),
the chromosomal pathogenicity island (PAI) PAI ICL3, and the autotransporter-
encoding gene sabA was examined by PCR. Furthermore, the occupation of the
chromosomal integration sites of the locus of enterocyte effacement (LEE),
selC, pheU, and pheV, as well as the Stx phage integration sites yehV, yecE,
wrbA, z2577, and ssrA, was analyzed. Moreover, the antibiotic resistance
phenotypes of all STEC strains were determined. Multilocus sequence typing
(MLST) was performed, and sequence types (STs) and sequence type complexes
(STCs) were compared with those of 42 hemolytic-uremic syndrome
(HUS)-associated enterohemorrhagic E. coli (HUSEC) strains. Besides 59 STs and
4 STCs, three larger clusters were defined in this strain collection. Clusters
A and C consist mostly of highly pathogenic eae-positive HUSEC strains and
some related food-borne STEC strains. A member of a new O26 HUS-associated
clone and the 2011 outbreak strain E. coli O104:H4 were found in cluster A.
Cluster B comprises only eae-negative food-borne STEC strains as well as
mainly eae-negative HUSEC strains. Although food-borne strains of cluster B
were not clearly associated with disease, serotypes of important pathogens,
such as O91:H21 and O113:H21, were in this cluster and closely related to the
food-borne strains. Clonal analysis demonstrated eight closely related genetic
groups of food-borne STEC and HUSEC strains that shared the same ST and were
similar in their virulence gene composition. These groups should be considered
with respect to their potential for human infection