Microbiology Ch 15 Review

  1. Pathogenicity
    The ability to cause disease
  2. Virulence
    The extent of pathogenicity
  3. What are some portals of entry?
    • -Mucous membranes
    • -skin
    • -Parenteral route-direct deposit
    • -Preferred portal of entry 
  4. Numbers of invading microbes

    Infectious dose for 50% of the test population
  5. Numbers of invading microbes
    Lethal dose (of a toxin) for 50% of the test population
  6. What are examples of Adherence 

    -contribute to virulence factor 
    • *Adhesins/ligands bind to receptors on host cells
    • -Glycocalyx: streptococcus mutans
    • -Fimbriae: Escherichia coli
    • -M protein: streptococcus pyogenes

    Form biofilms 
  7. How do pathogens Penetrate Host?

    -list all the methods 
    • Capsules
    • Cell wall components
    • Enzymes
    • Penetration into the Host cell cytoskeleton 
    • Antigenic variation

  8. How Pathogens penetrate Host

    • Prevent phagocytosis
    •   -streptococcus pneumoniae
    •   -Haemophilus influenzae
    •   -Bacillus anthracis 
  9. How Pathogens penetrate host

    Cell wall components 
    • -M Protein resists phagocytosis
    •     streptococcus pyogenes
    • -Opa Protein inhibits T helper cells
    •   Neisseria gonorrhoeae
    • -Mycolic acid (waxy lipid) resists digestion
    •    Mycobacterium tuberculosis 
  10. How pathogens penetrate host

    Coagulase: coagulates fibrinogen

    Kinases: digest fribrin clots

    Hyaluronidase: Hydrolyzes hyaluronic acid

    Collagenase: hydrolyzes collagen

    IgA proteases: Destroy IgA antibodies 
  11. How pathogens penetrate host

    Penetration into the Host cell cytoskeleton 
    -Invasins: salmonella alters hsost actin to enter a host cell

    -Use actin to move from one cell to the next: Listeria

  12. How pathogens penetrate host

    Antigenic Variation 
    Alter surfce proteins
  13. How Bacteria Damage Host Cells

    List them 
    • -Using the host's nutrients:siderophores
    • -Direct damage
    • -The production of toxins
    • -Exotoxins
    • -Endotoxins
    • -Membrane disrupting toxins
    • -A-B exotoxin
    • -Superantigens
    • -Exotoxin-protein
    • -Endotoxins and the Pyrogenic Response
    • -LAL assay 
  14. How bacteria damage host cells

    Using the host's nutrients: Siderophores

    Use host's iron, compete with transferrin
  15. How bacteria damage host cells

    Direct Damage 
    • -Disrupt host cell function
    • -Produce waste products
    • -Toxins
    • -Cell rupture
  16. How bacteria damage host cells

    The production of Toxins
    Toxins: substance that contributes to pathogenicity 
  17. Toxigenicity
    Ability to produce a toxin
  18. Toxemia
    Presence of toxin in the host's blood
  19. Toxoid: 
    Inactivated toxin used in a vaccine
  20. Antitoxin
    Antibodies against a specific toxin
  21. Exotoxins:   Specific for a structure or function in  a host cell

    list three kinds 
    • 1) AB
    • 2)Membrane disrupting
    • 3) Superantigens
  22. A-B Exotoxin
    Made of A subunit and B subunit

    A: active subunit

    B: the binding subunit 
  23. Membrane Disrupting
    • Lyse host's cell by  ; making protein channels in the plasma membrane  
    •      ex) of membrane disrupting toxins
    •                      Leukocidins
    •                      Hemolysins
    •                      Streptolysins

    -Disrupting phopholipid bilayer  
  24. Superantigens 
    • -Cause an intense immune response due to release of cytokines from host cells
    • -symptoms: fever, nausea, vomiting, diarrhea, shock and death

    T-cells -->cytokins-->inflammation--->organ failure 
  25. Endotoxins
    • -Gram Negative
    •  Always "Lipid A"
  26. How bacteria damage host cells

    LAL Assay 
    • -Limulus amoebocyte lysate assay
    • -Amoebocyte produces a clot
    • -Endotoxin causes lysis  
  27. Pathogenic Properties of Fungi
    • -Fungal waste products may cause symptoms
    • -chronic infections provoke an allergic response
    • -Tichothecene toxins inhibit protein synthesis
    • -Proteases
    • -Capsule prevents phagocytosis  
  28. Pathogenic Properties of Fungi
    • -Ergot Toxin  : Claviceps
    • -Aflatoxin: Aspergillus
    • -Mycotoxins: Neurotoxins: Phalloidin, amanitin,  
  29. Pathogenic Properties of Protozoa

    • -Presence of protozoa
    • -Protozoan waste products may cause symptoms
    • -Avoid host defenses by : growing in phagocytes, antigenic variation  
  30. Pathogenic Properties of Helminths
    • -use host tissue
    • -presence of parasite interferes with host function
    • -parasites metabolic waste can cause sypmtoms 
  31. Pathogenic properties of Algae
    • -Paralytic shellfish poisoning
    •      *Dinoflagellates
    •       *saxitoxin

  32. Portals of Exit
    • -Respirtatory tract: cougphing and sneezing
    • -Gastrointestinal tract: Feces and saliva
    • -Genitourinary tract: Urine and Vaginal secretions
    • -Skin
    • -Blood:biting arthropods and needles or syringes  
  33. Pathogenic properties of Fungi: 

    Ergot toxin:
    Ergot toxin: can cause gangrene if exposed

    Aflatoxin: given off by peanuts. Very potent toxin

    Mycotoxins: neurotoxins  
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Microbiology Ch 15 Review
Review ppt notes ch 15