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20 Cards in this Set
- Front
- Back
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Pathogenicity
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the ability to cause disease
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Virulence
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Virulence : the extent or degree of pathogenicity
~100 bacteria cause significant disease in humans |
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The Establishment of Disease
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1. Portal of Entry (correct portal / multiple portals)
2. Dose (sufficient number / virulence factors) 3. Adhere (adhesions) 4. Tissue penetration / invasion 5. Resist Host Defenses 6. Toxins |
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2. Effect of Number (Dose) : ID50 Experiment
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Relationship between Portal and Dose
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3. Adherence
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Adhesions / ligands on pathogen bind specifically* to receptors on host cells
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4. Penetration/Invasion in host cell
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invasins cause cell membrane to ruffel
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5. Resist Host Defenses (enzymes)
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Coagulase= coagulate blood (avoid bacteriocidal substances and antibodies)
bacteria coat themselves with fibrinogen fibrin (soluble) ——> fibrinogen (insoluble) Ex: Staphylococcus and Streptocccus IgA proteases= destroy IgA antibodies Ex: Neisseria gonorrhoeae and Neisseria meningitidis |
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Toxin
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Substances that contribute to pathogenicity
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Toxemia
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Presence of toxin the host's blood
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Toxoid
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Inactivated toxin used in a vaccine
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Antitoxin
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Antibodies against a specific toxin
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Exotoxin verses Endotoxin
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A-B Toxins
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Membrane-disrupting toxins
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Lyse host’s cells by:
form protein channels in the plasma membrane disrupting phospholipid bilayer Streptococcus pyogenes (enterotoxin A) necrotizing fascitus or flesh eating disease |
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Endotoxins Fever and Septic Shock
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Macrophages also release TNF-alpha (Tumor necrosis factor)
septic shock inflammatory mediator clotting, organ failure and circulatory collapse (No antitoxin stimulation - No toxoids available - No Immunity) |
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kinases
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dissolves blood clots
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hyaluronidase
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spreading factor dissolves tissues
gan gragrene- clostridium perfringenes |
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collagenase
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breaks down protein collagen
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Staphylococcus aureus TSST-1
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toxic shock syndrome result of superantigen- intense immune response
fever, nausea, vomiting, diarrhea, shock, death |
