Virulence Factors Part 1
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Virulence Factors Part 1

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Questions and Answers

What is the primary function of bacterial capsules?

  • To facilitate nutrient absorption
  • To enhance reproduction rates
  • To produce energy
  • To aid in adhesion and immune evasion (correct)

    • Which pathogen uses Type IV pili for attachment?

  • Streptococcus mutans
  • Streptococcus pyogenes
  • Enterotoxigenic E. coli
  • Neisseria gonorrhoeae (correct)

    • What component is produced by Mycobacterium tuberculosis that aids in immune evasion?

  • Fimbriae
  • Mycolic acid (correct)
  • Capsule
  • M protein

    • Which of the following is a characteristic of fimbriae produced by some Streptococcus species?

    <p>They contain M protein which inhibits phagocytosis.</p> Signup and view all the answers

    Enterotoxigenic E. coli (ETEC) uses which type of adhesin to promote diarrhea?

    <p>Type 1 fimbriae</p> Signup and view all the answers

    What happens to pH levels when cariogenic bacteria proliferate due to carbohydrate fermentation?

    <p>pH drops quickly, increasing susceptibility to enamel demineralization</p> Signup and view all the answers

    Which characteristic of Candida albicans contributes to its virulence?

    <p>Secreted aspartyl proteases known as ‘Sap Proteins’</p> Signup and view all the answers

    How does the herpes simplex virus evade the immune system?

    <p>By hiding in neurons and non-neuronal cells</p> Signup and view all the answers

    What role do cytotoxic T cells play in the host's response to pathogens?

    <p>They help identify pathogens for immune response but can lead to escape mutations.</p> Signup and view all the answers

    What is a key characteristic of pathogens that successfully survive in a host environment?

    <p>They evolve virulence factors to take advantage of the host.</p> Signup and view all the answers

    What structure do bacteria use to adhere to host cells?

    <p>Pili</p> Signup and view all the answers

    What is the function of adhesins in bacterial infections?

    <p>They bind to host cell receptors.</p> Signup and view all the answers

    Which of the following is NOT considered a mechanism of virulence in bacteria?

    <p>Metabolism alteration</p> Signup and view all the answers

    Which pathogen is associated with Protein F adhesin?

    <p>Streptococcus pyogenes</p> Signup and view all the answers

    What type of motility is associated with Class IV pili?

    <p>Twitching motility</p> Signup and view all the answers

    Which factor helps bacteria resist physical removal from host cells?

    <p>Adhesins</p> Signup and view all the answers

    What type of adhesin is associated with Streptococcus mutans?

    <p>Adhesin P1</p> Signup and view all the answers

    Which type of bacterial adhesion allows for a 'slingshot' movement on host cells?

    <p>Pili</p> Signup and view all the answers

    What is the term for the presence of pus-forming bacteria in the blood?

    <p>Pyaemia</p> Signup and view all the answers

    Which virulence factor enables Staphylococcus aureus to evade phagocytosis?

    <p>Production of coagulase</p> Signup and view all the answers

    What best describes antigenic drift in viruses?

    <p>Minor changes from point mutations</p> Signup and view all the answers

    What role do fimbriae play in the function of Porphyromonas gingivalis?

    <p>Stimulating immune responses</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Streptococcus mutans related to cariogenicity?

    <p>Antigenic variation</p> Signup and view all the answers

    How do pathogens typically destroy T lymphocytes?

    <p>Induction of apoptosis</p> Signup and view all the answers

    Which of the following factors is directly associated with the pathogenicity of Streptococcus mutans?

    <p>Modification of dental plaque ecology</p> Signup and view all the answers

    What is the primary function of kinases produced by some pathogens?

    <p>Digesting fibrin clots</p> Signup and view all the answers

    What role do exoenzymes play in pathogens?

    <p>Facilitate invasion and growth outside of pathogen cells</p> Signup and view all the answers

    What is true about endotoxins?

    <p>Stabilizes at high temperatures but harmful in high concentrations</p> Signup and view all the answers

    Which of the following describes exotoxins?

    <p>Active in low concentrations and specific to target cells</p> Signup and view all the answers

    What is the consequence of high endotoxin concentrations in the blood?

    <p>Causes severe drop in blood pressure and multi-organ failure</p> Signup and view all the answers

    Which category of exotoxins specifically targets cells and disrupts membranes?

    <p>Membrane disrupting</p> Signup and view all the answers

    What term describes the presence of toxins in the bloodstream?

    <p>Toxemia</p> Signup and view all the answers

    What is the mechanism through which exotoxins damage cells?

    <p>Targeting specific receptors on cells</p> Signup and view all the answers

    Which of the following describes the ability of a pathogen to produce toxins?

    <p>Toxigenicity</p> Signup and view all the answers

    Study Notes

    Virulence Factors

    • Adhesion - bacterial strategy to adhere to host cell surface. Prevents physical removal and allows colonization.
    • Pili - hair-like structures on bacterial surface. Allows bacterial movement along host cell surface.
    • Fimbriae - bristle-like bacterial appendages which aid in adhesion.
    • Capsules - Some bacteria produce capsules. Aid in adhesion and immune evasion.
    • Bacterial Cell Walls - Contain adhesins (surface proteins/glycoproteins) which bind to host cell surface receptors for adhesion.

    Specific Pathogens

    • Streptococcus pyogenes - utilizes Protein F.
    • Streptococcus mutans – dental caries. Utilizes Adhesin P1 to adhere to teeth.
    • Neisseria gonorrhoeae - utilizes Type IV pili to adhere to urethral epithelial cells.
    • Enterotoxigenic E. coli (ETEC) - utilizes Type I fimbriae to adhere to intestinal epithelial cells.

    Evasion of Phagocytosis (Antiphagocytic Factors)

    • Streptococcus – M protein in Fimbriae alters surface to inhibit phagocytosis.
    • Mycobacterium tuberculosis - produces mycolic acid in cell wall to deter killing mechanisms within phagocytes.

    Exoenzymes

    • Extracellular enzymes secreted by bacteria.
    • Invade deeper tissues for colonization.
    • Specific to particular tissue structures.
    • Enable bacterial invasion, support growth and evade the immune system.

    Toxins

    • Biological poisons produced by pathogens.
    • Endotoxins - produced by gram-negative bacteria.
    • Exotoxins - produced by gram-positive bacteria and some gram-negative bacteria.

    Terminology to Describe Pathogens in Bloodstream

    • Bacteraemia - presence of bacteria in the blood.
    • Pyaemia - presence of pus-forming bacteria in the blood.
    • Toxaemia - presence of toxins in the blood.
    • Septicaemia - multiplying bacteria in the blood.

    Virulence Factors Promoting Infection

    • Coagulase - enables coating with fibrin clots, preventing phagocytosis.
    • Kinases - stimulate digestion of fibrin clots for pathogen escape.
    • Antigenic Variation - surface proteins are altered to avoid immune recognition.
    • Leukocidins - destroy phagocytes.
    • Intracellular Position - pathogens reside inside host cells, evading immune defenses.

    Viral Virulence

    • Adhesins - mediated by viral capsid or membrane envelope. Enables interaction with specific cell receptors.
    • Antigenic Variation - antigenic drift and shift.
    • Antigenic Drift - minor changes in spike proteins due to point mutations.
    • Antigenic Shift - major changes in spike proteins due to gene re-assortment.

    Virulence Factors in Oral Health

    • Porphyromonas Gingivalis - utilizes fimbriae to modify immune responses and gingipains (proteases) to break down periodontal structural proteins.
    • Streptococcus Mutans - caries. Utilizes adhesion, acidogenicity, and acid tolerance.

    Herpes Simplex Virus

    • Hides in neurons and non-neuronal cells.
    • Reactivates during low immune resistance.

    Candida Albicans

    • Opportunistic human fungal infections.
    • Exoenzymes - secreted aspartyl proteases (Sap proteins).
    • Adhesins - aid in attachment.
    • Pleomorphism - adapts to environmental changes.

    Conclusion

    • Pathogens evolve to increase virulence and avoid immune responses.
    • Constantly interact with host cells in a dynamic process.
    • New virulence factors are countered by host defenses.
    • Pathogens produce 'escape mutations' to avoid immune targeting.
    • Most successful pathogens take advantage of the host without causing immediate death.

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