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Microbiologists use many terms to describe Shiga toxin and differentiate more than one unique form. Many of these terms are used interchangeably. Shiga toxin type 1 and type 2 (Stx-1 and 2) are the Shiga toxins produced by some E. coli strains. Stx-1 is identical to Stx of Shigella spp. or differs by only one amino acid. [6]
Escherichia coli O157:H7 is a serotype of the bacterial species Escherichia coli and is one of the Shiga-like toxin–producing types of E. coli.It is a cause of disease, typically foodborne illness, through consumption of contaminated and raw food, including raw milk and undercooked ground beef.
The verocytotoxin (shiga-like toxin) can directly damage renal and endothelial cells. Thrombocytopenia occurs as platelets are consumed by clotting. Hemolytic anemia results from intravascular fibrin deposition, increased fragility of red blood cells, and fragmentation.
Some strains of E. coli, for example O157:H7, can produce Shiga toxin. The Shiga toxin causes inflammatory responses in target cells of the gut, leaving behind lesions which result in the bloody diarrhea that is a symptom of a Shiga toxin-producing E. coli (STEC) infection.
An exotoxin is a toxin secreted by bacteria. [1] ... Shiga toxin and heat-labile enterotoxin from E. coli. By mechanism. Once in the cell, ...
The pathogen responsible was found to be an EAEC O104:H4 strain which was lysogenized by a Shiga toxin encoding phage (typically associated with Shiga toxin-producing Escherichia coli, which often encode the adhesin intimin). [7] [8] The putative cause of the outbreak were sprouted fenugreek seeds. [9]
Shiga-toxin directly activates the alternative complement pathway and also interferes with complement regulation by binding to complement factor H, an inhibitor of the complement cascade. Shiga-toxin causes complement-mediated platelet, leukocyte, and endothelial cell activation, resulting in systemic hemolysis, inflammation and thrombosis.
Also, IMViC is {+ + – -} for E. coli; as it is indole-positive (red ring) and methyl red-positive (bright red), but VP-negative (no change-colourless) and citrate-negative (no change-green colour). Tests for toxin production can use mammalian cells in tissue culture, which are rapidly killed by shiga toxin. Although sensitive and very ...