Bacterial Virulence Factors
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Questions and Answers

What is a characteristic of intracellular targets of bacterial virulence factors?

  • They are only produced by Gram-negative bacteria.
  • They are always membrane-bound.
  • They modulate the host cell metabolism or produce cell death. (correct)
  • They are secreted into the extracellular space.

    • What is an example of a type of toxin produced by endospore-forming bacteria?

  • Cell-surface active toxin
  • Anthrax toxin (correct)
  • Pore-forming toxin
  • Membrane-damaging toxin

    • What is a characteristic of AB toxins?

  • They are secreted into the extracellular space.
  • They only target Gram-positive bacteria.
  • They are composed of two subunits. (correct)
  • They are always membrane-bound.

    • What is the result of Shiga toxin activity?

    <p>Cell death.</p> Signup and view all the answers

    What is a characteristic of membrane-damaging toxins?

    <p>They are cytotoxic.</p> Signup and view all the answers

    What is the result of pore-forming toxin activity?

    <p>Dissolution of lipids.</p> Signup and view all the answers

    What is a characteristic of cell-surface active toxins?

    <p>They attached to a cell receptor and activate second messenger pathways.</p> Signup and view all the answers

    What is the result of lipase secreted toxins activity?

    <p>Dissolution of lipids.</p> Signup and view all the answers

    What is a characteristic of bacterial endospores?

    <p>They are highly resistant to environmental stress.</p> Signup and view all the answers

    What is the primary function of virulence factors in bacteria?

    <p>To enable bacteria to colonize and produce disease in hosts</p> Signup and view all the answers

    Which of the following is NOT a type of virulence factor?

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

    What is the role of pili in bacterial virulence?

    <p>To mediate host cell adhesion</p> Signup and view all the answers

    Which of the following processes is regulated by quorum-sensing?

    <p>All of the above</p> Signup and view all the answers

    What is the function of siderophore secretion in bacterial virulence?

    <p>To acquire nutrients</p> Signup and view all the answers

    What is the role of flagella in bacterial virulence?

    <p>To enhance motility</p> Signup and view all the answers

    What is the primary function of bacterial biofilm formation?

    <p>To protect bacteria from environmental stress</p> Signup and view all the answers

    Which of the following is a consequence of bacterial virulence factor regulation?

    <p>Tissue damage and inflammation</p> Signup and view all the answers

    What is the role of the two-component system in bacterial virulence?

    <p>To regulate virulence gene expression</p> Signup and view all the answers

    What is the function of the capsule in bacterial virulence?

    <p>To protect the bacteria from the immune system</p> Signup and view all the answers

    What is the primary function of quorum-sensing?

    <p>To coordinate gene expression in response to population density</p> Signup and view all the answers

    Which of the following is NOT a function of flagella?

    <p>Quorum-sensing</p> Signup and view all the answers

    What is the result of quorum-sensing in bacterial populations?

    <p>The bacteria coordinate their behavior as a community</p> Signup and view all the answers

    What is the result of encapsulation in Streptococcus?

    <p>The bacteria are more virulent and likely to cause septicemia and meningitis</p> Signup and view all the answers

    What is the role of autoinducers in quorum-sensing?

    <p>They induce gene expression in response to population density</p> Signup and view all the answers

    What is the primary function of biofilm formation?

    <p>To protect the bacteria from the immune system</p> Signup and view all the answers

    Which of the following is a function of flagella in bacterial virulence?

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

    What is the role of the capsule in Streptococcus?

    <p>To protect the bacteria from the immune system</p> Signup and view all the answers

    What is the result of superantigens triggering excessive stimulation of T lymphocytes?

    <p>All of the above</p> Signup and view all the answers

    What is the function of extracellular matrix toxins?

    <p>Allowing free-movement of bacteria</p> Signup and view all the answers

    What is the key recognition receptor for Lipid A component?

    <p>Toll-like receptor 4</p> Signup and view all the answers

    What is the effect of LPS on the immune system?

    <p>Immune dysregulation</p> Signup and view all the answers

    What is the type of toxin that triggers excessive stimulation of T lymphocytes?

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

    What is the function of cell-surface active toxins?

    <p>Attach to a cell receptor and activate second messenger pathways</p> Signup and view all the answers

    What is the effect of superantigens on T cells?

    <p>Massive T-cell proliferation</p> Signup and view all the answers

    What is the function of hyaluronic acids and collagen?

    <p>Forming extracellular matrix</p> Signup and view all the answers

    What is the result of LPS inducing signaling and immune dysregulation?

    <p>Fever, arthritis, and dermatitis</p> Signup and view all the answers

    What is the primary function of biofilms in relation to bacterial virulence?

    <p>To provide protection from the immune system and antibiotics</p> Signup and view all the answers

    Which of the following is a mechanism of transfer of virulence factors?

    <p>Conjugation of plasmids</p> Signup and view all the answers

    What is the composition of the matrix in biofilms?

    <p>Polysaccharides, proteins, and released DNA</p> Signup and view all the answers

    What is the result of the emergence and dissemination of antimicrobial drug resistance?

    <p>Selection of serious pathogenic strains in the clinics</p> Signup and view all the answers

    What is the role of bacteriophages in the transfer of virulence factors?

    <p>They transfer bacterial DNA from one bacterium to another</p> Signup and view all the answers

    What is the benefit of biofilms in terms of nutrient acquisition?

    <p>Improved nutrient uptake</p> Signup and view all the answers

    Which of the following is NOT a mechanism of transfer of virulence factors?

    <p>Fungal infections</p> Signup and view all the answers

    What is the role of transformation in the transfer of virulence factors?

    <p>Bacteria acquire free DNA from the environment</p> Signup and view all the answers

    What is the benefit of biofilms in terms of desiccation?

    <p>Improved protection from desiccation</p> Signup and view all the answers

    Study Notes

    Bacterial Virulence

    • Exotoxins: modulate host cell metabolism or produce cell death
    • AB toxins: a type of exotoxin
    • Type III Secretion System toxins: a type of exotoxin
    • Enterotoxin LT: a type of exotoxin
    • Shiga toxin: a type of exotoxin

    Endospores and Toxins

    • Bacillus anthracis: produces endospores that can contaminate soil and vegetation
    • Endospores: can survive for a long time outside of a host

    Membrane-Damaging Toxins

    • Pore-forming toxins: dissolve lipids in cell membranes
    • Lipase secreted toxins: a type of membrane-damaging toxin

    Cell-Surface Active Toxins

    • Attached to cell receptors and activate second messenger pathways
    • Trigger excessive stimulation of T lymphocytes, resulting in fever, arthritis, dermatitis, and shock

    Virulence Factors

    • Allow bacteria to colonize niches in hosts and produce disease
    • Enable processes such as adhesion, biofilm formation, motility, toxin secretion, immune evasion, and colonization
    • Bacterial cell-cell communication: allows bacteria to coordinate behavior and respond to their environment

    Surface-Associated Proteins

    • Adhesion: allows bacteria to attach to host cells and colonize niches
    • Motility: allows bacteria to move towards or away from stimuli
    • DNA uptake and transfer: allows bacteria to acquire new genes and traits
    • Efflux pumps: allow bacteria to remove toxins and antibiotics from their cells
    • Antibiotic secretion: allows bacteria to produce and secrete antibiotics
    • Siderophore secretion: allows bacteria to acquire iron from their environment
    • LPS (endotoxin): has diverse immunostimulatory and procoagulant effects

    Quorum-Sensing

    • Regulation of gene expression in response to fluctuations in cell population density
    • Mediated by chemical signal molecules (autoinducers)
    • Allows bacteria to coordinate behavior and respond to their environment

    Biofilm Formation

    • Clusters of bacteria attached to a surface and/or to each other and embedded in a self-produced matrix
    • Functions: protection from immune system, desiccation, and antibiotics; improved acquisition of nutrients; improved bacterial-bacterial interactions

    Transfer of Virulence Factors

    • Transformation: bacteria acquire free DNA from the environment, including virulence factor genes
    • Transduction: bacteriophages transfer bacterial DNA, including virulence factor genes, from one bacterium to another
    • Conjugation: one bacterium can transfer a plasmid, which can contain virulence factor genes, to another bacterium

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    Related Documents

    Bacteriology II: Virulence and Pathogenicity (Ross University) PDF

    Description

    This quiz covers bacterial virulence factors, including exotoxins, intracellular targets, and their effects on host cell metabolism and death. It also touches on AB toxins and the Type III Secretion System.

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