Staphylococcus aureus
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Current revision
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 |
[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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.
