Staphylococcus aureus
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| - | Superantigens- (PTSAgs) have superantigen activities that induce toxic shock syndrome (TSS). The staphylococcal enterotoxins, which cause a form of food poisoning, are included in this group. | + | '''Superantigens'''- (PTSAgs) have superantigen activities that induce toxic shock syndrome (TSS). The staphylococcal enterotoxins, which cause a form of food poisoning, are included in this group. |
| - | Exfoliative toxins- EF toxins are implicated in the disease staphylococcal scalded-skin syndrome (SSSS), which occurs most commonly in infants and young children. The protease activity of the exfoliative toxins causes peeling of the skin observed with SSSS. | + | '''Exfoliative toxins'''- EF toxins are implicated in the disease staphylococcal scalded-skin syndrome (SSSS), which occurs most commonly in infants and young children. The protease activity of the exfoliative toxins causes peeling of the skin observed with SSSS. |
| - | Other toxins- Toxins that act on cell membranes include alpha-toxin, beta-toxin, delta-toxin, and several bicomponent toxins. The bicomponent toxin Panton-Valentine leukocidin (PVL) is associated with severe necrotizing pneumonia in children. | + | '''Other toxins'''- Toxins that act on cell membranes include alpha-toxin, beta-toxin, delta-toxin, and several bicomponent toxins. The bicomponent toxin Panton-Valentine leukocidin (PVL) is associated with severe necrotizing pneumonia in children. |
Revision as of 09:48, 8 July 2010
Staphylococcus aureus
It is a facultatively anaerobic, gram-positive coccus and is the most common cause of staph infections. It is frequently part of the skin flora found in the nose and on skin.
| Kingdom | Eubacteria |
|---|---|
| Phylum | Firmicutes |
| Class | Bacilli |
| Order | Bacillales |
| Family | Staphylococcaceae |
| Genus | Staphylococcus |
| Species | S. aureus |
| Binomial | Staphylococcus aureus |
Contents |
Surface Characteristics
The wall of Staphylococcus aureus consist of Type 5 capsular polysaccharide consists of following residues : -4)-β-D-ManpNAcA3Ac-(1-->4)-α-L-FucpNAc-(1-->3)-β-D-FucpNAc-(1-
Its large polysaccharide capsule protects the organism from recognition by the cow's immunological defenses.
Transmission
Spread of S. aureus takes place through human-to-human contact, although recently some veterinarians have discovered that the infection can be spread through pets, with environmental contamination thought to play a relatively unimportant part.
Pathogenic Activity
Various strains are responsible for food poisoning through the production of an enterotoxin. It may occur as a commensal on skin; it also occurs in the nose frequently (in about a third of the population) and throat less commonly. Some strains of S. aureus, which produce the exotoxin TSST-1, are the causative agents of toxic shock syndrome. Some strains of S. aureus also produce an enterotoxin that is the causative agent of S. aureus gastroenteritis.
Virulence
It produces several virulence factors that are responsible for virulence. Some virulence factors are:
Superantigens- (PTSAgs) have superantigen activities that induce toxic shock syndrome (TSS). The staphylococcal enterotoxins, which cause a form of food poisoning, are included in this group.
Exfoliative toxins- EF toxins are implicated in the disease staphylococcal scalded-skin syndrome (SSSS), which occurs most commonly in infants and young children. The protease activity of the exfoliative toxins causes peeling of the skin observed with SSSS.
Other toxins- Toxins that act on cell membranes include alpha-toxin, beta-toxin, delta-toxin, and several bicomponent toxins. The bicomponent toxin Panton-Valentine leukocidin (PVL) is associated with severe necrotizing pneumonia in children.
