Microbiology: Pathogens and Virulence Factors
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Questions and Answers

What is the primary requirement for pathogens to replicate in a host?

  • Susceptibility of the host to the pathogen
  • High infectious dose of the pathogen
  • Presence of virulence factors
  • Favourable conditions within the host (correct)

    • Where do intracellular pathogens grow and multiply?

  • Outside of host cells
  • Within host cells (correct)
  • In both within and outside host cells
  • In blood and tissue fluids

    • What determines the degree of damage caused by a pathogen?

  • Virulence factors (correct)
  • Infectious dose of the pathogen
  • Pathogenicity of the pathogen
  • Susceptibility of the host

    • What is the ability of a microbe to cause disease?

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

    What is the term for the ability of a pathogen to spread to adjacent tissues?

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

    What type of pathogens can grow both within and outside of host cells?

    <p>Facultative intracellular pathogens</p> Signup and view all the answers

    What is the term for the ability of a pathogen to adhere to host cells or tissues?

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

    What is the term for the process by which pathogens spread from the inoculation site to deeper tissues?

    <p>Passive penetration</p> Signup and view all the answers

    What is the term for the ability of a pathogen to cause localised infections?

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

    What is the term for the production of specific products and/or enzymes that promote spreading of pathogens?

    <p>Passive penetration</p> Signup and view all the answers

    What is the primary characteristic of superantigens?

    <p>They stimulate T-cells to release cytokines and can trigger a cytokine storm</p> Signup and view all the answers

    What is the main difference between exotoxins and endotoxins?

    <p>Exotoxins are heat-labile, while endotoxins are heat-stable</p> Signup and view all the answers

    What is the role of nutrition in host susceptibility to infection?

    <p>It affects the immune system's ability to respond to infection</p> Signup and view all the answers

    What is the term for the number of pathogens required to infect 50% of an experimental group of hosts?

    <p>Infectious dose 50</p> Signup and view all the answers

    What is the term for the period after pathogen entry, before signs and symptoms appear?

    <p>Incubation period</p> Signup and view all the answers

    What is the primary way in which pathogens evade the immune system?

    <p>By evolving strategies to evade or interfere with the immune response</p> Signup and view all the answers

    What is the term for the component of the pathogen's cell wall that can trigger septic shock?

    <p>Lipid A</p> Signup and view all the answers

    What is the term for the stage of disease where signs and symptoms are most severe?

    <p>Period of illness</p> Signup and view all the answers

    What is the role of genetic predisposition in host susceptibility to infection?

    <p>It affects the immune system's ability to respond to infection</p> Signup and view all the answers

    What is the term for the stage of disease where signs and symptoms begin to disappear?

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

    What is a characteristic shared by most exotoxin producers?

    <p>They are Gram-negative bacteria that have toxin genes in their plasmids or prophage DNA</p> Signup and view all the answers

    What is the primary function of neutralising antibodies against exotoxins?

    <p>To neutralise the toxin and prevent its effects</p> Signup and view all the answers

    What is the mechanism by which superantigens exert their effects?

    <p>By stimulating T-cells to release cytokines</p> Signup and view all the answers

    What is the primary difference between the infectious dose 50 and the lethal dose 50?

    <p>The infectious dose 50 is the dose that infects 50% of experimental animals, while the lethal dose 50 is the dose that kills 50% of experimental animals</p> Signup and view all the answers

    What is the primary role of the immune system in preventing disease?

    <p>To eliminate most microbes before they can cause disease</p> Signup and view all the answers

    What is the primary way in which pathogens disseminate within the host?

    <p>Through the bloodstream</p> Signup and view all the answers

    What is the primary determinant of the degree of damage caused by a pathogen?

    <p>The combination of the pathogenicity of the microbe and the defence mechanisms of the host</p> Signup and view all the answers

    What is the primary function of endotoxins?

    <p>To exert effects in the host when the pathogen lyses or divides</p> Signup and view all the answers

    What is the primary role of sanitation in preventing disease?

    <p>To reduce the number of pathogens in the environment</p> Signup and view all the answers

    What is the primary characteristic of the prodromal stage of disease?

    <p>The signs and symptoms are not clear enough for diagnosis</p> Signup and view all the answers

    What is the primary reason why pathogens must find favourable conditions in the host?

    <p>To replicate and cause disease</p> Signup and view all the answers

    What is the main difference between facultative and obligate intracellular pathogens?

    <p>Their ability to grow outside of host cells</p> Signup and view all the answers

    What is the role of virulence factors in determining the degree of disease caused by a pathogen?

    <p>They affect the severity of the disease</p> Signup and view all the answers

    What is the primary way in which pathogens establish a localised infection?

    <p>Through the adherence of pathogens to host cells</p> Signup and view all the answers

    What is the term for the ability of a pathogen to spread to adjacent tissues beyond the initial site of infection?

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

    What is the primary role of lytic substances produced by pathogens during active penetration of host tissue?

    <p>To degrade carbohydrate-protein complexes between cells</p> Signup and view all the answers

    What is the primary difference between the growth of extracellular and intracellular pathogens?

    <p>The location of growth, either inside or outside of host cells</p> Signup and view all the answers

    What is the role of adherence to host cells or tissues in the pathogenesis of disease?

    <p>It allows for colonisation of the host</p> Signup and view all the answers

    What is the primary reason why some pathogens are able to establish a systemic infection?

    <p>Their ability to disseminate widely around the body</p> Signup and view all the answers

    What is the primary characteristic of the interaction between pathogens and the host that determines the outcome of infection?

    <p>The balance between the pathogen's virulence and the host's susceptibility</p> Signup and view all the answers

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