Microbial Pathogenesis Overview
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Questions and Answers

What role does temperature play for pathogens in a host?

  • It activates their virulence genes. (correct)
  • It reduces their need for iron.
  • It enhances their ability to evade detection.
  • It prevents them from altering their surface antigens.

    • Which strategy is employed by extracellular pathogens to avoid phagocytosis?

  • Changing their genetic material rapidly.
  • Forming capsules to prevent immune cell binding. (correct)
  • Producing toxins that harm host cells.
  • Living inside host cells to avoid detection.

    • What is the primary purpose of pili in microbial pathogenesis?

  • To generate metabolic energy for the microorganism
  • To replicate DNA within the host
  • To transport nutrients across membranes
  • To facilitate attachment to host cells (correct)

    • How do some pathogens utilize quorum sensing?

    <p>To alter their virulence factor expression based on population density.</p> Signup and view all the answers

    How do pathogens primarily avoid the body's mechanisms of preventing colonization?

    <p>By attaching to cellular structures</p> Signup and view all the answers

    What distinguishes type I pili from type IV pili?

    <p>Type IV pili can retract and are involved in twitching motility unlike type I pili</p> Signup and view all the answers

    What distinguishes facultative intracellular pathogens from other pathogens?

    <p>They may live both inside and outside host cells.</p> Signup and view all the answers

    Which of the following statements about antigen variation is true?

    <p>It enables pathogens to escape immune detection.</p> Signup and view all the answers

    What is the function of the adhesion protein located at the tip of the pilus?

    <p>It binds to carbohydrates on host cell surfaces</p> Signup and view all the answers

    Which process allows some bacteria to form a protective layer that enhances pathogenicity?

    <p>Biofilm formation</p> Signup and view all the answers

    What is a function of protein A in Staphylococcus aureus?

    <p>It sequesters antibodies by binding to their Fc region.</p> Signup and view all the answers

    Which component initiates pilus assembly in bacteria like E. coli?

    <p>The Sec system</p> Signup and view all the answers

    What is the primary function of Type I pili in uropathogenic E. coli?

    <p>Promoting attachment to epithelial cells</p> Signup and view all the answers

    Which process involves uropathogenic E. coli migrating to the bladder?

    <p>Colonization of vaginal areas</p> Signup and view all the answers

    What structural feature makes Type IV pili distinct from Type I pili?

    <p>Dynamic and thin</p> Signup and view all the answers

    During which step do uropathogenic E. coli internalize after binding to bladder cells?

    <p>Adherence &amp; internalization</p> Signup and view all the answers

    What is the role of the FimH protein in the adherence of UPEC?

    <p>Binding to mannosylated glycoproteins</p> Signup and view all the answers

    What is a major advantage of intracellular bacterial communities (IBCs) formed by UPEC?

    <p>Reinvasion of neighboring cells</p> Signup and view all the answers

    Which pathogen is known for utilizing pili for pathogenicity, alongside Uropathogenic E. coli?

    <p>Vibrio cholerae</p> Signup and view all the answers

    What is a characteristic feature of uropathogenic E. coli's behavior in the bladder?

    <p>Formation of biofilms that enhance resistance</p> Signup and view all the answers

    What is the role of nonpilus adhesions in bacterial attachment?

    <p>They bind to host proteins to facilitate closer attachment.</p> Signup and view all the answers

    Which of the following correctly describes a function of Neisseria meningitidis type IV pili?

    <p>They enhance intimate attachment through nonpilis membrane proteins.</p> Signup and view all the answers

    What distinguishes extracellular pathogens from facultative intracellular pathogens?

    <p>Extracellular pathogens primarily exist outside the host cells.</p> Signup and view all the answers

    Which protein is associated with Streptococcus and binds to host fibronectin?

    <p>Streptococcus protein F</p> Signup and view all the answers

    What strategy do intracellular pathogens commonly employ to avoid destruction within host cells?

    <p>They modify their surface antigens.</p> Signup and view all the answers

    What is the role of protein M in Streptococcus bacteria?

    <p>Binds to host fibronectin and complement regulatory factor H.</p> Signup and view all the answers

    Why do pathogens distinguish between intracellular and extracellular existence?

    <p>To evade the host's immune system effectively.</p> Signup and view all the answers

    Which of the following best describes obligate intracellular pathogens?

    <p>They require host cells for replication and survival.</p> Signup and view all the answers

    What is a common characteristic of Bordetella pertactin in relation to its host?

    <p>It binds to host integrin to aid bacterial adhesion.</p> Signup and view all the answers

    What is one impact of pressure ulcers on host tissues?

    <p>Cause tissue ischemia due to prolonged pressure.</p> Signup and view all the answers

    Study Notes

    Microbial Pathogenesis

    • Major "tools" microbes use to cause disease: Microbial pathogens use various attachment mechanisms, avoid the immune system, and damage host cells through toxins and effector proteins.
    • Pathogen Entry & Colonization: The first step of infection is attachment, achieved through pili adhesins and non-pili adhesins. Pili are hairlike appendages with adhesion proteins at the tip.
    • Biofilms: Biofilms provide a protective layer for pathogens, making them harder to kill.
    • Type I pili: Static, hairlike appendages used for attachment
    • Type IV pili: Dynamic, thin, and flexible pili used for "twitching motility."
    • Colonization: The process of establishing a presence and multiplying in the host
    • Nonpilus Adhesions: Cell wall-associated proteins, like pertactin, protein F, and protein M, bind to host proteins for more intimate attachment
    • Surviving within a Host: Pathogens distinguish between extracellular and intracellular environments, and display different strategies to survive and avoid the immune system.
    • Extracellular Pathogens: Exist outside of host cells. They avoid the immune system by forming capsules, producing proteins that bind to antibodies, and changing surface antigens.
    • Intracellular Pathogens: Live inside host cells to avoid the immune system.
      • Facultative Intracellular Pathogens: Can invade host cells but also survive outside. Examples: Salmonella, Shigella, Listera
      • Obligate Intracellular Pathogens: Can only survive and reproduce inside a host cell. Examples: Rickettsia, Coxiella, Bartonella
    • Host Damage and Manipulation: Pathogens damage host cells by targeting components of the cell, disrupting signaling pathways, interfering with protein synthesis, and disrupting the cellular membrane.
    • Extracellular Immune Avoidance:
      • Capsules: Coat bacterial cell walls to prevent phagocytes from binding.
      • Cell Surface Proteins: Sequester antibodies, like protein A in S. aureus.
      • Antigenic Variation: Vary surface antigens to avoid immune detection.
      • Quorum Sensing: Use cell-to-cell communication to evade the immune system.
    • Intracellular Immune Avoidance:
      • Phagosome Escape: Escape the phagosome to avoid destruction by the immune system
      • Phagosome Modification: Modify the phagosome to create a suitable environment for survival
      • Inhibition of Phago-lysosome Fusion: Prevent phago-lysosome fusion to avoid degradation by lysosomes

    Exotoxin Modes of Action

    • Exotoxins: Proteins produced by bacteria that can damage host cells.
    • Cellular Targets of Bacterial Toxins: Pores, actin polymerization, second messenger signaling, the cytoskeleton, vesicular trafficking, cell-cell adhesion, protein synthesis, nucleic acid synthesis, and cell wall synthesis.
    • Staphylococcal Alpha Toxin: Forms a seven-membered transmembrane pore in target cell membranes, causing cell lysis.
    • Cholera Toxin: An AB toxin that disrupts signal transduction by associating with the G protein and increasing cAMP, leading to diarrhea.
    • Diphtheria Toxin: An AB toxin that disrupts protein synthesis by interfering with elongation factor 2, leading to cell death.
    • Shiga Toxin: An AB toxin that inhibits protein synthesis by blocking the translation of ribosomes, leading to cell death.
    • Anthrax Toxin: A tripartite toxin complex consisting of protective antigen (PA), edema factor (EF), and lethal factor (LF). PA binds to host cell receptors, allowing EF and LF to enter the cell and exert their effects.
      • EF: Causes fluid accumulation in the tissues.
      • LF: Disrupts cellular signaling, leading to cell death
    • Endotoxins: Lipopolysaccharide (LPS) found in the outer membrane of Gram-negative bacteria. Can cause fever, inflammation, and shock.

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    Microbiology Chapter 18: Microbial Pathogenesis PDF

    Description

    Explore the critical mechanisms that microbial pathogens utilize to establish infection and cause disease. This quiz covers attachment methods, the formation of biofilms, and strategies for surviving within a host. Test your understanding of how specific structures, like pili and adhesions, facilitate colonization and immune evasion.

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