conclusions this study indicated the contamination of lettuce by stec strains and its possible role as the source of infection. resistance to both tetracycline and ampicillin may be considered as an emergency alarm for a multidrug resistance of stec strains. results eight samples were positive for presence of stec strains, three contained stx1, five contained stx2, and one sample was positive f...

Virulence of enterohemorrhagic Escherichia coli (EHEC) strains depends on production of Shiga toxins. These toxins are encoded in genomes of lambdoid bacteriophages (Shiga toxin-converting phages), present in EHEC cells as prophages. The genes coding for Shiga toxins are silent in lysogenic bacteria, and prophage induction is necessary for their efficient expression and toxin production. Under ...

Shiga toxin 1 and 2 production is a cardinal virulence trait of enterohemorrhagic Escherichia coli infection that causes a spectrum of intestinal and systemic pathology. However, intestinal sites of enterohemorrhagic E. coli colonization during the human infection and how the Shiga toxins are taken up and cross the globotriaosylceramide (Gb3) receptor-negative intestinal epithelial cells remain...

background shiga-toxigenic escherichia coli is an important human pathogen cause of diarrhea, hemorrhagic colitis, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura in humans is a significant public health. objectives the aim of this study was to determine the molecular characteristics and antimicrobial resistance properties of shiga toxigenic escherichia coli (stec) strains wit...

the aim of this study was to identify virulent shiga toxin-producing escherichia coli (stec) strains isolated from faecal samples of 100 clinically healthy calves. in the present study, a total of 100 escherichia coli (e. coli) isolates from clinically healthy calves belonging to 6 different farms located in khorasan razavi province, iran, were examined for presence of virulence genes character...

The production of Shiga toxin by a bacterial strain is necessary for induction of enteropathogenic haemolytic uraemic syndrome (HUS). Only strains that produce the toxin are associated with HUS. These include enterohaemorrhagic Escherichia coli, Shigella dysenteriae and rarely Citrobacter freundii [1, 2]. All strains associated with haemorrhagic colitis and HUS are Gram-negative, thus producing...

Strains of Escherichia coli previously implicated or proven to be causes of diarrhea were examined for production of a toxin similar to that of Shigella dysenteriae type 1 (Shiga). Organisms grown in an iron-depleted broth were lysed by pressure disruption followed by ultracentrifugation. Saline-dialyzed extracts were tested for cytotoxic effects on HeLa cells that were neutralizable with antis...

The B subunit of Shiga toxin and the Shiga-like toxins (SLTs) mediates receptor binding, cytotoxic specificity, and extracellular localization of the holotoxin. While the functional receptor for Shiga toxin, SLT type I (SLT-I), and SLT-II is the glycolipid designated Gb3, SLT-II variant (SLT-IIv) may use a different glycolipid receptor. To identify the domains responsible for receptor binding, ...

Escherichia coli Shiga-like toxin I, a close relative of Shiga toxin and a distant relative of the ricin family of plant toxins, inhibits eukaryotic protein synthesis by catalyzing the depurination of adenosine 4324 in 28S rRNA. By comparing the crystallographic structure of ricin with amino acids conserved between the Shiga and ricin toxin families, we identified seven potential active-site re...