Introduction to Human Pathogenic Bacteria: Extracellular vs Intracellular Lifecycle
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Questions and Answers

What protects intracellular pathogens from humoral antibodies?

  • Effector proteins
  • Membrane-disrupting enzymes
  • Cellular immune response (correct)
  • Specialized mechanisms

    • Which type of pathogens can only reproduce inside host cells?

  • Listeria monocytogenes
  • Salmonella spp.
  • Mycobacterium leprae (correct)
  • Legionella pneumophila

    • What is the purpose of exoenzymes produced by pathogens during invasion?

  • To trigger an immune response
  • To facilitate colonization of host tissues (correct)
  • To destroy host cells
  • To neutralize lysosomal enzymes

    • Which bacteria exploit nutrients in the host cell during their intracellular 'lifestyle'?

    <p>Chlamydia spp.</p> Signup and view all the answers

    What is a characteristic feature of facultative intracellular pathogens?

    <p>They can reproduce both inside and outside of host cells.</p> Signup and view all the answers

    Which mechanism allows Listeria monocytogenes to spread from one host cell to another?

    <p>Replication in the host cell cytosol</p> Signup and view all the answers

    What is a characteristic feature of obligate intracellular bacteria mentioned in the text?

    <p>Requirement of viable eukaryotic host cells for growth</p> Signup and view all the answers

    What is the role of the pore-forming toxin LLO in the context of Listeria infection?

    <p>Facilitates escape from the phagosome</p> Signup and view all the answers

    Which bacterium is mentioned as an example of an obligate intracellular pathogen in the text?

    <p>Coxiella burnetii</p> Signup and view all the answers

    What is the primary action of chlamydial elementary bodies (EB) upon attachment to epithelial cells?

    <p>Prevent fusion of phagosome with host lysosome</p> Signup and view all the answers

    What is the primary function of effector proteins secreted by certain pathogens during invasion into host cells?

    <p>Trigger entry into host cell</p> Signup and view all the answers

    Which bacterial mechanism of invasion relies on surface proteins binding to receptors on host cell membranes?

    <p>Zipper mechanism</p> Signup and view all the answers

    What is the significance of avoiding the microbicidal lysosome for intracellular survival strategies of pathogens?

    <p>To subvert endosomal trafficking</p> Signup and view all the answers

    Which bacterial pathogen utilizes effector molecules to cause membrane ruffles in the process of membrane ruffling during invasion?

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

    What is a common strategy used by intracellular pathogens to enhance protection against immune recognition?

    <p>Remodeling of the vacuole</p> Signup and view all the answers

    How do Mycobacterium tuberculosis, Legionella pneumophila, and Salmonella species evade being digested by the phagocyte?

    <p>Prevent fusion of phagosome with lysosome and remain alive and dividing within the phagosome</p> Signup and view all the answers

    What is the mechanism used by Salmonella to evade the host's immune system after entering macrophages?

    <p>Prevent fusion of the phagosome with the lysosome and proliferate within the SCV</p> Signup and view all the answers

    How do L.monocytogenes and Shigella escape the phagosome and multiply within the cytoplasm?

    <p>Prevent lysis of the phagosome to maintain intracellular survival</p> Signup and view all the answers

    What is the main strategy used by intracellular pathogens like Mycobacterium tuberculosis to survive within phagocytes?

    <p>Prevent fusion of phagosome with lysosome and remain alive within it</p> Signup and view all the answers

    How does Legionella pneumophila differ in its intracellular survival strategy compared to Mycobacterium tuberculosis?

    <p><strong>Legionella pneumophila</strong> prevents lysis of the phagosome for intracellular survival</p> Signup and view all the answers

    Which term describes the Coxiella burnetii compartment where it replicates inside alveolar macrophages?

    <p>Coxiella-containing vacuole (CCV)</p> Signup and view all the answers

    Which of the following is NOT an obligate intracellular bacteria from the Rickettsiales group mentioned in the text?

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

    What is the degradative pathway involving lysosomes and cytosolic content that plays a role in cellular homeostasis and innate immunity?

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

    Which bacterial pathogen uses ActA, Phospholipase C, and Autolysosome for intracellular survival and replication?

    <p>Listeria monocytogenes</p> Signup and view all the answers

    What factor explains the limited niche for bacterial replication in different cell types due to the failure of bacteria to use cytosolic substrates?

    <p>Bacterial tropism</p> Signup and view all the answers

    What is a common strategy employed by intracellular pathogens to resist being destroyed inside host cells?

    <p>Preventing phagolysosome fusion</p> Signup and view all the answers

    Which category of bacteria is likely to possess effector proteins that aid in invasion of host cells?

    <p>Obligate intracellular bacteria</p> Signup and view all the answers

    Phagosomal membrane disruption is a critical step for some pathogens to survive intracellularly. Which mechanism is commonly employed for this disruption?

    <p>Interference with actin polymerization</p> Signup and view all the answers

    Intracellular survival mechanisms often involve acquiring nutrients within host cells. What is a typical nutrient source for these bacteria?

    <p>Host cell cytoplasm</p> Signup and view all the answers

    Obligate intracellular bacteria have specialized adaptation for survival. Which of these characteristics is typically associated with this group of pathogens?

    <p>Dependence on host cells for replication</p> Signup and view all the answers

    What is the role of haemolysin C and phospholipases in the escape strategy of Rickettsia prowazekii?

    <p>Disrupting the vacuolar membrane</p> Signup and view all the answers

    What is a common feature of cytosolic pathogens during cell-to-cell spread?

    <p>Enclosed in a secondary double-membrane vacuole</p> Signup and view all the answers

    Why do cytosolic bacteria polymerize actin at the bacterial pole?

    <p>For intracellular and intercellular motility</p> Signup and view all the answers

    What is the immediate result of bacteria entering the host cell in a primary vacuole?

    <p>Secretion of bacterial escape proteins</p> Signup and view all the answers

    Which step follows bacterial internalization in a secondary vacuole during cell-to-cell spread?

    <p>Disruption of double-membrane vacuole membranes</p> Signup and view all the answers

    What is the significance of bacteria being free in the cytosol for obligate intracellular pathogens?

    <p>It signifies escape from host cell vacuoles</p> Signup and view all the answers

    How do bacteria facilitate their entry into host cells during the initial stages of infection?

    <p>Through secretion of bacterial escape proteins</p> Signup and view all the answers

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