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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]
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.
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 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.
Shigella is a genus of bacteria that is Gram negative, facultatively anaerobic, non–spore-forming, nonmotile, rod shaped, and is genetically nested within Escherichia.The genus is named after Kiyoshi Shiga, who discovered it in 1897.
Shiga studied 32 dysentery patients and used Koch's Postulates to successfully isolate and identify the bacterium causing the disease. He continued to study and characterize the bacterium, identifying its methods of toxin production i.e. Shiga Toxin , and worked tirelessly to create a vaccine for the disease.
Cholera toxin, shiga toxin, and SubAB toxin all have B subunits that are made up of five identical protein components, meaning that their B subunits are homopentamers. Pertussis toxin is different where its pentameric ring is made up of four different protein components, where one of the components is repeated to form a heteropentamer. [5]