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28 Cards in this Set
- Front
- Back
Three portals of entry
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-Mucous Membranes
-Skin -The Parenteral Route |
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Mucous Membranes
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Access through respiratory tract,
GI tract, Genitourinary tract, and conjunctiva |
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Skin
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Protective barrier, Some enter through hair follicles/ sweat glands.
Larvae and Fungi contact skin |
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Parenteral Route
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Through split/ open membranes or skin
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LD50
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Lethal dose for 50% of a sample population (potency of toxin)
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The LD50 of botulinum toxin is 0.03 ng/kg; the LD50 of Salmonella toxin is 12 mg/kg. Which is the more potent toxin?
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Botulinum toxin more potent than salmonella
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How would a drug that binds mannose (a sugar receptor) on human cells affect a pathogenic bacterium?
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The adhesins/ ligands would be unable to bind to receptors on the host cell
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Common function of capsules and M proteins
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Both resist phagocytosis
Capsules: glycocalyx increase virulence M Proteins: heat-resistance, acid-resistance, mediates attachment to host epithelial cells |
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Expect bacteria to make coagulase and kinase simultaneously?
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No:
Coagulase- enzymes coagulate fibrinogen in blood (clot) Kinases- break down fibrin (digest clots) |
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Why doesn’t the influenza vaccine offer more than a few months of protection?
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It alters it surface antigens, by a process called "antigenic variation"- By the time the body mounts an immune response, the pathogen has already altered its antigens and is unaffected by the antibodies
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How does E. coli cause membrane ruffling?ill
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Change plasma membrane at point of contact; Microbes produce invasins (surface proteins) that rearrange nearby actin filaments of the cytoskeleton; ruffling allows microbe to be engulfed by the cell
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Siderophores
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Bacterial iron-binding proteins secreted by pathogens when they need iron; take iron away from iron-transport proteins, binding and forming a complex
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How does toxigenicity differ from direct damage?
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Direct: Rupture host cell, releasing and spreading pathogen
Toxin: inhibit protein synthesis, destroy blood cells, disrupt nervous system, cause fever |
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Exotoxin V. Endotoxin.
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Ex: produced within bacteria and secreted into surroundings or released by lysis
En: lipid portions of the LPS in the outer membrane of g(-) cell wall; are released when the bacteria die and cell wall breaks apart |
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Difference between food infection and intoxication
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Infection: Bacteria present grows and produces illness
Intoxication: Bacteria produces toxins which cause illness |
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Washwater containing Pseudomonas was sterilized and used to wash cardiac catheters. Three patients developed fever, chills, and hypotension following cardiac catheterization. The water and catheters were sterile. Why did the patients show these reactions? How should the water have been tested?
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The bacteria was killed but the toxin was still present
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How can lysogeny turn the normally harmless E. coli into a pathogen?
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It can undergo lysogenic conversion, change in the characteristics of the microbe due to a prophage (DNA of bacteriophage incorporated into bacterial chromosome); bacteria immune to infection by same phage and prophage can cause pathogenesis
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Define cytopathic effects
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Visible signs of viral infections
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Examples of Cytopathic effects
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-mitosis prevention
-lysis -form inclusion bodies -cell fusion -antigenic changes -chromosomal changes -transformation |
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Cytocidal Effects
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Viruses cause cell death
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Noncytocidal Effects
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Viruses damage cells, but do not cause death
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Syncytium (a CPE)
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aggregates of giant multinucleate cells- diagnostic of measles, mumps, common cold
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Transformation (a CPE)
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Results in immortal cells b/c of no contact inhibition
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Virulence factor (contributes to the pathogenicity) of fungi
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-Tichothecene toxins inhibit protein synthesis (Fusarium)
-Proteases (Candida) -Capsule prevents phagocytosis (Cryptococcus) |
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Virulence factor (contributes to the pathogenicity) of protozoan
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Antigenic variation (trypanosoma) stays one step ahead of host’s immune response
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Virulence factor (contributes to the pathogenicity) of helminthic
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Parasitically use host tissue for their growth
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Virulence factor (contributes to the pathogenicity) algal
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Produce paralytic neurotoxins (saxitoxin)
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List microbial portals of exit
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Respiratory: coughing/ sneezing
GI Tract: Saliva/ Feces Genitourinary: genital secretions (Blood or Wound infections) |