GAS strains express many virulence factors including surface protein M, streptolysins, streptokinase, hyaluronidase, peptidoglycan, and teichoic acid. Protein M is considered as the main virulence factor, limiting phagocytosis, disturbing the function of complement, and being responsible for adhesion [4].

Which streptococci produce a number of virulence factors?

Streptococcus pyogenes possesses a wide variety of virulence factors and can cause severe invasive infections. Most S. pyogenes express surface-located fibronectin-binding proteins as major invasion molecules. We identified 2 novel fibronectin-binding proteins (FbaA and FbaB) in S.

What toxin does Streptococcus pyogenes release?

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.

Are Exoenzymes virulence factors?

Virulence factors contribute to a pathogen’s ability to cause disease. Exoenzymes and toxins allow pathogens to invade host tissue and cause tissue damage. Exoenzymes are classified according to the macromolecule they target and exotoxins are classified based on their mechanism of action.

What makes Streptococcus virulent?

Virulence factors of group A streptococci include (1) M protein and lipoteichoic acid for attachment; (2) a hyaluronic acid capsule that inhibits phagocytosis; (3) other extracellular products, such as pyrogenic (erythrogenic) toxin, which causes the rash of scarlet fever; and (4) streptokinase, streptodornase (DNase B …

What are the characteristic virulence factors found in strep?

What are pathogen virulence factors?

Virulence factors are molecules produced by bacteria, viruses, fungi, and protozoa that add to their effectiveness and enable them to achieve the following: Specific pathogens possess a wide array of virulence factors.

Are toxins virulence factors?

Another class of virulence factors are called toxins. Toxins are chemicals that are released from bacteria that can damage host tissue in a multitude of ways. For example, the bacteria associated with causing the disease botulism releases a toxin called botulinum toxin.

Are capsules a type of virulence factor?

Capsule (also known as K antigen) is a major virulence factor of bacteria, e.g. all of the principal pathogens which cause pneumonia and meningitis, including Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Klebsiella pneumoniae, Escherichia coli, and group B streptococci have polysaccharide capsules on their surface.

What are the characteristics of Streptococcus?

Morphology and Growth Requirements. Microscopically,Streptococcus pyogenes is a spherical bacterium (cocci) that appears in chain-like formations.