Acute Morphology of Streptococcus pyogenes
Abstract: Streptococcus pyogenes is a gram positive coccus bacterium that is extremely common bacteria. This bacterium is part of group A streptococci, which meant that it has a certain type of polysaccharide antigen on its cell surface. It is commonly known as pharyngitis, or strep throat and produces over twenty exotoxins. Even though this bacterium has been around for thousands of years it still has a susceptibility to penicillin and there have only been a few cases of resistance.
Streptococcus pyogenes is a gram positive bacteria that is associated with multiple types of diseases. Streptos means a chain of links and coccus means a round object. Together this describes the shape of Streptococcus pyogenes, a round chain of ten or more cocci, each measuring 0.5 to 0.75 μm in diameter. This bacterium can cause scarlet fever, streptococcal pharyngitis and erysipelas in humans. It is identified mainly by its ability to create β-haemolysis in blood agar plates.
Streptococci can be separated into groups by a polysaccharide antigen that is deep inside the cell wall. The groups are labeled by the letters ranging from A to R, each group represents a different type of organism that it mostly infects. Group A is mainly pathogenic to humans, while group B is found in cattle. Groups C to R infect animals of lesser complexity. Streptococcus pyogenes is part of group A, which means that the polysaccharide antigen is composed of rhamnose and N-acetylglucosamine and its main host is in humans.
The morphology of S. pyogenes is a chain of cocci that are normally in groups of ten and each cocci range in diameter from 0.5 to 0.75 μm. They are nonmotile, which means that they
have no form of movement of their own and only move by vectors. While they cannot form spores like anthrax, S. pyogenes can form capsules which are made of hyaluronic acid. This capsule is nonantigenic and appears to macrophages as being similar to that of connective tissue and the body will not recognize the bacteria as a foreign body. The enzyme hyaluronidase can destroy the connective tissue that contains hyaluronic acid, but this enzyme is not usually found in bacteria that also have a capsule that is made of hyaluronic acid. Even though the bacteria cannot move on its own it can attach to the host through the use of two different forms, they are; lipoteichoic acid and M protein. The M protein and lipoteichoic acid act as a bridge in which the S. pyogenes can adhere to erythrocytes, epithelial cells, and phagocytes. Both also act to help prevent phagocytosis of the bacteria.
Streptococcus pyogenes is known to form β-haemolysis on blood agar plates. This is shown on the plates by a clear area around the colony. This is because the bacteria have completely lysed the red blood cells in the agar. There are two types of chemicals that cause this to happen, they are; streptolysin O and streptolysin S. Streptolysin O is an antigenic protein...