What is the function of the Erythrogenic toxin of Streptococcus pyogenes?
Erythrogenic toxins, also referred to as streptococcal pyrogenic exotoxins, are secreted by strains of the bacterium Streptococcus pyogenes. SpeA and speC are superantigens, which induce inflammation by nonspecifically activating T cells and stimulating the production of inflammatory cytokines.
What disease involves Erythrogenic toxin?
Scarlet fever results from infection with a streptococcal strain that elaborates streptococcal pyrogenic exotoxins (erythrogenic toxins). Although this disease is usually associated with pharyngeal infections, it may follow streptococcal infections at other sites, such as wound infections or puerperal sepsis.
Is Erythrogenic toxin an endotoxin?
The peptidoglycan component of cell walls has many of the biologic features of endotoxins. The exotoxins of group A streptococci include the erythrogenic toxins (pyrogenic exotoxins) and the cytolytic toxins (streptolysins S and O).
What are super antigenic toxins responsible for?
Superantigens are predominantly bacterial in origin, such as staphylococcal enterotoxin and toxin-1 responsible for toxic shock syndrome.
Which toxin of Streptococcus causes hemolysis?
S pyogenes elaborates 2 distinct hemolysins. These proteins are responsible for the zone of hemolysis observed on blood agar plates and are also important in the pathogenesis of tissue damage in the infected host. Streptolysin O is toxic to a wide variety of cell types, including myocardium, and is highly immunogenic.
Which group of streptococci is associated with Erythrogenic toxin production quizlet?
Which group of streptococci is associated with erythrogenic toxin production? Group A β-hemolytic streptococci are the cause of scarlet fever, and some strains produce toxins (pyrogenic exotoxins A, B, and C) that cause a scarlatiniform rash.
Which toxin causes scarlet fever?
It is caused by streptococcal pyrogenic exotoxins (SPEs) types A, B, and C produced by group A beta-hemolytic streptococci (GABHS) found in secretions and discharge from the nose, ears, throat, and skin. Scarlet fever may follow streptococcal wound infections or burns, as well as upper respiratory tract infections.
What toxin causes scarlet fever?
What is the function of a superantigen in T cell activation?
A superantigen is a molecule that is able to elicit T lymphocyte responses by circumventing normal antigen processing and presentation functions. Superantigens are defined by their ability to stimulate a large fraction of T cells via interaction with the TCR Vβ domain (Figure 4.11).
How does a super antigen work?
Superantigens are bacterial proteins that generate a powerful immune response by binding to Major Histocompatibility Complex class II molecules on antigen-presenting cells and T cell receptors on T cells.
What toxin causes beta hemolysis?
A zone of beta-hemolysis surrounding colonies on blood-agar media is a hallmark phenotypic feature of the pathogens group A Streptococcus (GAS) and group B Streptococcus (GBS). In each case, lysis of red blood cells reflects the action of a potent protein exotoxin.
What is slo toxin?
Streptolysin O (SLO; slo), is a bacterial toxin that has four protein domains which is known to make the plasma membranes in animal cells permeable.
Which tests could be used to distinguish between Staphylococcus aureus and Staphylococcus epidermidis?
Staphylococcus aureus produces free coagulase; Staphylococcus epidermidis does not. The coagulase test is useful for differentiating potentially pathogenic Staphylococci such as Staphylococcus aureus from other Gram positive, catalase-positive cocci.
How does Staphylococcus differ from micrococcus?
Micrococci may be distinguished from staphylococci by a modified oxidase test23,24. Their colonies are usually pigmented in shades of yellow or red and grow on simple media. The optimum growth temperature is 25-37°C.
What is the pathophysiology of scarlet fever?
Scarlet fever is caused by the same type of bacteria that causes strep throat — group A streptococcus (strep-toe-KOK-us), also called group A strep. In scarlet fever, the bacteria release a toxin that produces the rash and red tongue.
How does a superantigen work?
What does superantigen a cause?
Superantigens cause symptoms via release of immune cytokines. These proteins should be considered potential causes of illnesses such as rheumatic fever, arthritis, Kawasaki syndrome, atopic dermatitis, and guttate psoriasis because of their potent immune system-altering capacity.
How do super antigens lead to life threatening symptoms?
This excessive uncoordinated release of cytokines, (especially TNF-α), overloads the body and results in rashes, fever, and can lead to multi-organ failure, coma and death. Deletion or anergy of activated T-cells follows infection. This results from production of IL-4 and IL-10 from prolonged exposure to the toxin.
What is the function of MHC proteins?
The function of MHC molecules is to bind peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T cells.