1 / 21

Microbial Mechanisms of Pathogenicity

15. Microbial Mechanisms of Pathogenicity. Microbial Mechanisms of Pathogenicity. Pathogenicity : The ability to cause disease. Virulence : The extent of pathogenicity. Portals of Entry. Mucous membranes Skin Parenteral route. Numbers of Invading Microbes. Dosage Amounts

lucia
Download Presentation

Microbial Mechanisms of Pathogenicity

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 15 Microbial Mechanisms of Pathogenicity

  2. Microbial Mechanisms of Pathogenicity • Pathogenicity: The ability to cause disease. • Virulence: The extent of pathogenicity.

  3. Portals of Entry • Mucous membranes • Skin • Parenteral route

  4. Numbers of Invading Microbes • Dosage Amounts • ID50: Infectious dose for 50% of the test population. • LD50: Lethal dose (of a toxin) for 50% of the test population. • Examples • Botulinum 0.03 ng/kg • Shiga toxin 250 ng/kg • Staphylococcal enterotoxin 1350 ng/kg

  5. Bacillus Anthracis Infectious Dosage

  6. Adherence • Adhesions/ligands bind to receptors on host cells • Glycocalyx • Biofilms • Fimbriae • Pili • Flagella

  7. Enzymes • Bacterial Capsules • Help Prevent Phagocytosis • Increase Virulence • Anchor Bacterial Cells

  8. Penetration into the Host Cell Figure 15.2

  9. Toxins • Toxin: Substances that contribute to pathogenicity. • 2 main types of toxins • Toxigenicity: Ability to produce a toxin. • Toxemia: Presence of toxin in the host's blood. • Toxoid: Inactivated toxin used in a vaccine. • Antitoxin: Antibodies against a specific toxin.

  10. Endotoxins Figure 15.4b

  11. Exotoxin Example: Botulinum Toxin Figure 15.4a

  12. Exotoxins • A-B toxins Figure 15.5

  13. Exotoxins • Membrane-disrupting toxins • Lyse host’s cells by • Making protein channels in the plasma membrane • Disrupting phospholipid bilayer.

  14. Exotoxins • Superantigens • Cause an intense immune response due to release of cytokines from host cells. • Fever, nausea, vomiting, diarrhea, shock, and death.

  15. Exotoxins • Specific for a structure or function in host cell Figure 15.4a

  16. Exotoxins

  17. Endotoxins Figure 15.4b

  18. Endotoxins The fever caused by endotoxin release: Figure 15.6

  19. Cytopathic Effects of Viruses Table 15.4

  20. Portals of Exit • Respiratory tract • Coughing and sneezing • Gastrointestinal tract • Feces and saliva • Genitourinary tract • Urine and vaginal secretions • Skin • Blood • Biting arthropods and needles or syringes

  21. Mechanisms of Pathogenicity Figure 15.9

More Related