Microbiology Chapter 3: Principles of Disease and Epidemiology
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Microbiology Chapter 3: Principles of Disease and Epidemiology

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Questions and Answers

What is the role of coagulase in staphylococcal lesions?

  • To contribute to the formation of fibrin walls (correct)
  • To activate a proteolytic enzyme of plasma
  • To dissolve red blood cells
  • To hydrolyze hyaluronic acid
  • What is the function of hyaluronidases?

  • To form fibrin walls
  • To activate a proteolytic enzyme of plasma
  • To hydrolyze hyaluronic acid (correct)
  • To dissolve red blood cells
  • What is the effect of streptokinase on plasma?

  • It dissolves red blood cells
  • It activates a proteolytic enzyme (correct)
  • It hydrolyzes hyaluronic acid
  • It forms fibrin walls
  • What is the function of IgA1 proteases?

    <p>To split IgA1 at specific bonds in the hinge region</p> Signup and view all the answers

    What is the term for the process by which bacteria stick to the surfaces of host cells?

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

    What is the term for microorganisms that are present at a certain time and then disappear?

    <p>Transient Microbiota</p> Signup and view all the answers

    What is a person or animal with asymptomatic infection that can be transmitted to another susceptible person or animal?

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

    What is the result of elimination of a microbe from the host?

    <p>Removal of the microbe from the host</p> Signup and view all the answers

    What is defined as the interruption of normal tissue structure and/or function?

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

    What is the ability to study genes associated with virulence?

    <p>Molecular Koch's Postulate</p> Signup and view all the answers

    What is the ability of an infectious agent to cause disease?

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

    What is the term for large groups of genes associated with pathogenicity and located on the bacterial chromosome?

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

    What is the term for the microbial flora harbored by normal, healthy individuals?

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

    What is the term for the ability of bacteria to cause infection and disease?

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

    What is the scientific study of disease?

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

    What is the term for the 'hairlike' structures that extend from the bacterial cell surface and help mediate adherence to host cell surfaces?

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

    What is the term for the cause of disease?

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

    What is the term for the protein that contributes to the adherence of streptococci to buccal epithelial cells?

    <p>Lipoteichoic acid</p> Signup and view all the answers

    What is the term for a microorganism that does not cause disease?

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

    What is the term for the ability of a microorganism to produce a toxin that contributes to the development of disease?

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

    What is the type of toxin that is produced by both Gram-positive and Gram-negative bacteria?

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

    What is the enzyme that degrades collagen, the major protein of fibrous connective tissue, and promotes the spread of infection in tissue?

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

    Study Notes

    Virulence and Disease

    • Virulence: an organism's capacity to cause disease, with virulent agents causing disease when introduced into the host in small numbers.
    • Adherence: the process by which bacteria stick to the surfaces of host cells.
    • Carrier: a person or animal with asymptomatic infection that can be transmitted to another susceptible person or animal.
    • Infection: multiplication of an infectious agent within the body, involving invasion or colonization of the body by pathogenic organisms.

    Pathogens and Disease Development

    • Pathogen: a microorganism capable of causing disease.
    • Nonpathogen: a microorganism that does not cause disease, may be part of the normal microbiota.
    • Opportunistic Pathogen: an agent capable of causing disease only when the host's resistance is impaired.
    • Pathogenicity: the ability of an infectious agent to cause disease.
    • Pathology: the scientific study of disease.
    • Etiology: the cause of disease.
    • Pathogenesis: the study of how disease develops.

    Microbiota and Normal Flora

    • Microbiota: microbial flora harbored by normal, healthy individuals.
    • Normal microbiota: abundant normal microbiota that usually do not produce disease, achieving a balance that ensures the survival, growth, and propagation of both the bacteria and the host.
    • Resident Microbiota: microorganisms that remain throughout an individual's life.
    • Transient Microbiota: microorganisms that are present at a certain time then disappear.

    Portals of Entry and Pathogenicity Islands

    • Portals of entry: respiratory, gastrointestinal, genital, and urinary tract.
    • Pathogenicity Islands: large groups of genes associated with pathogenicity, located on the bacterial chromosome.

    Bacterial Virulence Factors

    • Adherence factors: necessary for bacteria to adhere to cells of a tissue surface.
    • Pili: thick rodlike appendages.
    • Fimbriae: shorter, hairlike structures that help mediate adherence of bacteria to host cell surfaces.
    • Lipoteichoic acid: causes adherence of streptococci to buccal epithelial cells.
    • Invasion plasmid antigens (IpA-D): proteins that contribute to the invasion process.

    Toxins

    • Toxins: produced by bacteria, classified into two groups: endotoxin and exotoxin.
    • Exotoxin: excreted by living cells, produced by both Gram-positive and Gram-negative bacteria.
    • Endotoxin: integral part of the cell wall of Gram-negative bacteria, released on bacterial death and in part during growth.

    Additional Virulence Factors

    • Collagenase: degrades collagen, promoting spread of infection in tissue.
    • Coagulase: contributes to the formation of fibrin walls around staphylococcal lesions.
    • Hyaluronidases: enzymes that hydrolyze hyaluronic acid, a constituent of the ground substance of connective tissue.
    • Streptokinase (fibrinolysin): activates a proteolytic enzyme of plasma.
    • Hemolysins: cytolysins that dissolve red blood cells.
    • Leukocidins: cytolysins that kill tissue cells or leukocytes.

    Immune Response

    • IgA: immunoglobulin A, the secretory antibody on mucosal surfaces.
    • IgA1: has a series of amino acids in the hinge region that are not present in IgA2.
    • IgA1 proteases: split IgA1 at specific proline--threonine or proline--serine bonds in the hinge region, inactivating its antibody activity.

    Elimination and Damage

    • Elimination: removal of the microbe from the host by physical factors, an immune response, therapy, or out competition by existing microbes, or if the microbe causes sufficient damage to the host, death.
    • Damage: interruption of normal tissue structure and/or function at the cellular, tissue, or organ level.

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    Description

    Review key concepts in microbiology, including virulence, adherence, carrier, and infection. Understand the principles of disease and epidemiology in this chapter 3 review.

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