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26 Cards in this Set
- Front
- Back
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pathogenicity
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ability of a m/o to cause disease
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virulence
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the degree of pathogenicity
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virulence factors
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those properties an organism has that makes it virulent
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ID50
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infectious dose that causes infection in 50% of hosts
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LD50
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lethal dose for 50% of hosts
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leukocidins, hemolysins
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cause RBS and WBC to lyse
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coagulase
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clots fibrinogen in blood. forms clot around cell. protects cell from phagocytosis
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bacterial kinases
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break down clots. allows m/o to spread away from site of infection. used therapeutically
use of streptokinase or staphylokinase |
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hyaluronidase
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the spreading factor
breaks down hyaluronic acid between cells and connective tissue. m/o penetrates tissue Clostridium perfringens |
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collagenase
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allows collagen to break it down
Clostridium perfringens |
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antigenic variation
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bacteria change surface antigen
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exotoxin vs endotoxin
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exo - proteins excreted by a bacterium
endo - lipid A of LPS of Gram - cells |
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exotoxins
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most extracellular enzymes
coded for by plasmids or chromosome of cell secreted by both gram - and + |
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antitoxin
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antibody to toxin
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toxoid
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chemically modified toxin used as a vaccine
DTaP vaccine contains diphtheria and tetanus toxoids |
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A-B toxins (Type II toxins)
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‘A’ for active, and ‘B’ for binding. The B component binds to the cell’s membrane, and the A component enters the cell and carries out the toxic activity
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Membrane-distrupting toxins (type II toxins)
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cause host membrane to lyse
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Superantigens (type I toxins)
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powerful protein antigens that stimulate T cells to release huge amounts of cytokines
causes shock |
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Corynbacterium diphtheriae
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diphtheria toxin is an A-B toxin that stops protein synthesis
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Clostridium bolulinum
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botulinum toxin is a neurotoxin (A-B) that causes flaccid paralysis
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Clostridium tetani
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tetanus toxin is a neurotoxin (A-B) that causes spastic paralysis
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Vibrio cholerae
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cholera toxin is an enterotoxin (A-B) that causes massive diarrhea
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Staphylococcus aureus
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produces an entterotoxin that causes food poisoning
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Endotoxin
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LPS on outermembrane of Gram - cells
polysaccharide 'O' antigen lipid A causes fever maybe shock |
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endotoxic shock
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septic shock
macrophages secrete tumor necrosis factor (TNF) |
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R factors
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plasmids that carry genes that encode proteins to make an organism resistant to one or more antibiotics
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