Bacterial Pathogenesis Flashcards
Catalase function and where its found
Breaks down hydrogen peroxide into oxygen and water
Found in staph
Not in negative
Needed to deal with oxygen rich environment
Staph aureus is ONLY
Coagulase positive staph species
Coagulase function
Activates prothrombin and results in a fibrin clot
S aureus colonization
Adhesins bind fibronectin and collagen
S aureus invasion and spread
Staphylokinase - lyses fibrin
Hyaluronidase, collagenase, elastase
S aureus invasion
PVL - Panton valentine leukocydin lyses cells, especially neutrophils
Capsule is antiphagocytic which leads to C3b inativation
Protein A - binds Fc portion of IgG and interferes with opsonization and phagocytosis
Also uses coagulase and alpha toxin
TSST
From staph aureus
Creates superantigen endotoxin…creates irreversible bridge between APC and T cell which results in massive cytokine release (IL-2, IFN-gamma, TNF-alpha)…sends body into SIRS, sepsis, shock, and die
Ultimately due to overraction of the immune system
Scalded skin syndrome clinical manifestation
Skin is reddened and followed by blisters that contain fluid lacking bacteira or WBCs…outer epidermis peels off
No scarring because dermis is not affected by toxin
Scalded skin syndrome pathogenesis
Exofoliative toxin causes dissolution of epidermal desmosomes which hold together of cytoplasmic membranes of adjoining cells
From staph aureus
Endotoxin
Anything bound to the membrane that elicits an immune response (LPS, Lipid A…more common in gram neg)
Exotoxin - more common in gram positive
More common in gram positive
Secreted
Strep classified by
M protein and hemolytic ability
GBS
From strep agalactiae…can cause neonatal meningitis
VIrulence factors of strep pneumonia
Polysaccharide capsule inhibits C3b depostion
Pilli for resp epithelial attachment
IgA protease
Strep pneu shape
Lancet shaped, gram positive diplocooci
