What are antigenic types of streptococci?

Classification and Antigenic Types They are divided into three groups by the type of hemolysis on blood agar: β-hemolytic (clear, complete lysis of red cells), α hemolytic (incomplete, green hemolysis), and γ hemolytic (no hemolysis).

Are Streptococcus antigens?

Numerous streptococcal antigens have been proposed as the target antigen. The lead causal candidate is streptococcal exotoxin B (Spe B), which can activate the alternative complement pathway, resulting in low serum complements, and has affinity for glomerular proteins and plasmin.

How does Streptococcus pyogenes reproduce?

Streptococcus pyogenes is a bacteria, so it reproduces by binary fission. Binary fission is a form of asexual reproduction in a single-celled organisms. This process occurs by one cell dividing into two cells of the same size. Binary fission is used by most prokaryotes.

Are antigens produced by antibodies?

Antibodies are host proteins that are produced by the immune system in response to foreign molecules that enter the body. These foreign molecules are called antigens, and their molecular recognition by the immune system results in selective production of antibodies that are able to bind the specific antigen.

What is the shape and morphology of a streptococcus bacteria?

The bacterium Streptococcus mutans is an example of a spherical (coccus) bacterium. This species of bacteria commonly aggregates into pairs and short chains.

Is Streptococcus pyogenes facultative anaerobe?

S. pyogenes is a facultative anaerobe and is grown at 37°C in either ambient air or in 5–10% CO2. Like all streptococci, GAS is both catalase and oxidase negative.

What is the cell wall structure of Group A streptococcus?

The cell wall structure of group A streptococci is among the most studied of any bacteria . The cell wall is composed of repeating units of N-acetylglucosamine and N-acetylmuramic acid, the standard peptidoglycan.

What are the different types of Streptococcus?

Streptococci are grouped into alpha (Str. viridans), beta (Str. pyogenes), and gamma (Str. faecalis) haemolytic streptococci : Haemolytic streptococci can be classified into 20 serological groups (A-V except I, J) on the basis of the nature of carbohydrate ‘C’ antigen.

What is the morphology of Streptococcus cocci?

Morphology and Staining of Streptococci: Individual cocci are spherical (0.5-1 µ in diameter) and arranged in chains (Fig. 24.1). The lengths of chains are variable. The chains are longer in liquid than in solid media. Streptococci are Gram-positive. As the culture ages, they loose their Gram- positivity and appear to be Gram-negative.

What are the characteristics of anaerobic Streptococcus?

Anaerobic streptococci participate in mixed infections of the abdomen, pelvis, brain, and lungs. Structure Streptococci are Gram-positive, nonmotile, nonsporeforming, catalase-negative cocci that occur in pairs or chains.