What is the pathogenic substance of Candida albicans?

Streptococcus is a common bacterium, which is more common in cases of wound suppuration. Streptococcus mainly exists in feces and the human nasal cavity and basically does not cause disease to the body. The pathogenic substance of streptococcus is generally group A streptococcus. This type of streptococcus has a certain degree of invasiveness and is relatively common in invading the human body, causing further damage to wounds.

Streptococci are another common type of pyogenic cocci. They are widely present in nature, in human and animal feces, and in the nasopharynx of healthy people. Most of them are non-pathogenic. The medically important streptococci include Streptococcus pyogenes, Streptococcus viridans, Streptococcus pneumoniae, Streptococcus agalactiae, etc. The diseases caused by it in humans mainly include: suppurative inflammation, toxic diseases and hypersensitivity diseases.

Pathogenic substances

Group A Streptococcus has strong invasive ability and can produce a variety of invasive enzymes and exotoxins.

1.M protein is a protein component in the cell wall of streptococci, which has anti-phagocytic and anti-phagocytic intracellular bactericidal effects. Purified M protein can precipitate fibrinogen, agglutinate platelets and leukocytes, lyse polymorphonuclear cells, and inhibit the migration of cells in capillaries. M protein is antigenic, stimulates the body to produce type-specific antibodies, and is related to allergic diseases.

2. Lipoteichoic acid (LTA) is related to bacterial adhesion to the host cell surface. Most LATs are located between the cell membrane and peptidoglycan, extending to the bacterial cell surface through peptidoglycan pores. There are LAT binding sites on the cell membranes of human oral mucosa, skin epithelial cells, blood cells, etc.

3. Hyaluronidase (Hyaluronidaes) can decompose hyaluronic acid in the intercellular matrix, making it easier for pathogens to spread in the tissue. Also called diffusion factor.

4. Streptokinase (SK), also known as Streptococcal fibrinolysin, is a kinase that can activate plasma protease in the blood to become plasma protease, which can dissolve blood clots or prevent plasma coagulation, and is conducive to the spread of bacteria in tissues. Heat resistant, remains active after heating at 100℃ for 50 minutes. Streptokinase antibodies can neutralize the activity of this enzyme.

5. Streptodonase (SD) is also known as deoxyribonuclease (Streptococcal deoxyribonuclease). It is mainly produced by group A, C, and G streptococci. This enzyme can break down the highly sticky DNA in thick pus, making the pus thinner and easier to spread. The corresponding antibodies produced have the activity of neutralizing the enzyme. Skin testing with streptokinase and streptodorase preparations is a method for measuring the body's cellular immunity.

6. Streptolysin has the function of dissolving red blood cells, killing white blood cells and poisoning the heart. There are mainly two types: "O" and "S".

Oxygen-sensitive streptolysin O (SLO) is a protein containing an -SH group that is sensitive to oxygen. When exposed to oxygen, the SH group is oxidized to an -SS- group, temporarily losing its hemolytic ability. If reducing agents such as 0.5% sodium sulfite and cysteine ​​are added, the hemolytic ability can be restored. Hemolysin O can destroy white blood cells and platelets. Animal experiments have also confirmed that it has acute toxic effects on the heart and can cause cardiac arrest. It has strong antigenicity. 2 to 3 weeks after infection, more than 85% of the patients will produce anti-"O" antibodies, which can last for months or even years after recovery. It can be used as an auxiliary diagnosis for recent streptococcal infection or possible rheumatic activity.

Oxygen-stable streptolysin "S" (Streptolysin S, SLS) is a small molecule glycopeptide with no antigenicity. Stable to oxygen, sensitive to heat and acid. The transparent hemolysis seen on the blood agar plate is caused by "S", which can destroy white blood cells and platelets and can quickly cause death when injected intravenously into animals. Intraperitoneal injection of mice induced renal tubular necrosis.