تويت
Staphylococcus aureus : Bacteria from a gram positive cocci
Characteristics:
Characteristics:
- [*=left]cause most Staphylococcal diseases .
[*=left]Gr + Ve Cocci .
[*=left]Non Sporing , Non Motile Cocci
[*=left]Usually has capsulate .(polysaccharide)&slim layer.
[*=left]Facultative anaerobic .
Habitat
- [*=left]Humans ( nose , skin , mucous ) .
[*=left]Always present in hospital environment .
[*=left]Survives drying . Tolerant of Salts
Transmission
- [*=left]Direct contact .
[*=left]Airborne route .
Pathogenesis
- [*=left]Capsule= inhibits chemotaxis and phagocytosis. And facilitates adherence to foreign bodies.
[*=left]*Peptidoglycan= inhibits phagocytosis.
[*=left]Hemolysins = lyse RBCs
[*=left]Coagulase = converts fibrinogen to fibrin(clots plasma)
[*=left]catalase= remove of hydrogen peroxide.
[*=left] Fibrinolysin = Digest fibrin
[*=left] Leucocidin = kills leukocytes
[*=left] DNase = hydrolyses DNA
[*=left] Protein A = Antiphagocytosis (inhibits antibody clearance) and anticomplementary.
[*=left]Enterotoxin = Vomiting & diarrhea
[*=left]TSS toxin-1 = produce leakage or destruction of endothelial cells.
[*=left]Exfoliative Toxin = Skin exfoliative
Diseases
- [*=left]Superficial infection(scalded skin syndrome) ( SSS )
[*=left]Surgical Wound Infection
[*=left]Toxic Shock Syndrome . (( TSS ))
[*=left]Toxic Food Poisoning . (( TFP ))
[*=left]Septicemia , Endocarditis , pneumonia .
Laboratory Identification
- [*=left]White or Golden Colonies on Blood Agar
[*=left]Catalase +Ve , Coagulase +Ve , DNase + Ve
Example of the image Staphylococcus aureus
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