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Questions and Answers

What is the definition of pathogenicity?

  • The process of a microorganism establishing in a host
  • The actual damage or injury that impairs host function
  • The ability of a parasite to inflict damage on the host (correct)
  • The enhanced ability of microbes to attach to host tissues

    • How do pathogens typically adhere to epithelial cells?

  • By gaining access to host tissues through puncture wounds or cuts
  • Through interactions between molecules on the pathogen and host tissues (correct)
  • By establishing an infection through mucous membranes
  • Via the formation of biofilm on the host

    • What is the role of microbial adherence in disease initiation?

  • Sufficient to initiate disease
  • Necessary but not sufficient to start disease (correct)
  • Critical in establishing an infection
  • Not required for disease initiation

    • How do pathogens gain access to host tissues?

    <p>Through a portal of entry such as mucous membranes, skin surface, or puncture wounds</p> Signup and view all the answers

    Which of the following is true about the virulence of a pathogen?

    <p>Virulence may be encoded by chromosomal genes or by mobile elements</p> Signup and view all the answers

    What is the main cause of nosocomial infections?

    <p>Surgery, biopsy, catheterization, hypodermic injection</p> Signup and view all the answers

    What makes individuals more susceptible to infections?

    <p>Many factors including lifestyle choices and living conditions</p> Signup and view all the answers

    Which infections are considered opportunistic?

    <p>Those caused by organisms that do not cause disease in healthy hosts</p> Signup and view all the answers

    Which structure is involved in specific adherence in infections by various bacteria?

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

    What is the term for a pathogen's relative ability to cause disease, quantified by factors such as mortality and illness?

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

    What is the term for the decrease or loss of virulence in pathogens, which can be developed in the laboratory through passages?

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

    What provides attachment sites for bacteria in saliva, leading to dental plaque and tooth decay?

    <p>Acid glycoproteins</p> Signup and view all the answers

    What involves the growth of microorganisms in host tissues, beginning at birth with exposure to harmless bacteria and viruses?

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

    Which bacterial structure has specific receptors for attachment to host tissues and can evade the host defense system?

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

    What is the term for a pathogen's ability to grow in host tissue, spread, and cause disease, leading to bacteremia and septicemia?

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

    Which pathogen requires few infectious agents to cause disease?

    <p>Virulent pathogens</p> Signup and view all the answers

    What are structures involved in specific adherence in infections by various bacteria, along with fimbriae?

    <p>Pili and flagella</p> Signup and view all the answers

    What is the term for the growth of microorganisms in host tissues, beginning at birth with exposure to harmless bacteria and viruses?

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

    Which term refers to the ability of a pathogen to cause disease?

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

    What is the term for the ability of a pathogen to cause disease, leading to bacteremia and septicemia?

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

    Which type of toxin inhibits muscle contraction by cleaving proteins involved in acetylcholine release?

    <p>Botulinum toxin</p> Signup and view all the answers

    Which type of toxin causes massive fluid secretion in the small intestine by activating adenylyl cyclase?

    <p>Cholera enterotoxin</p> Signup and view all the answers

    Which type of toxin inhibits protein synthesis by catalyzing ADP-ribosylation of elongation factor EF-2?

    <p>Diphtheria toxin</p> Signup and view all the answers

    Which type of toxin floods neuromuscular junctions with acetylcholine, causing muscle contraction?

    <p>Tetanus toxin</p> Signup and view all the answers

    Which type of toxin promotes blood clotting to block access to the bacteria?

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

    Which type of toxin dissolves blood clots to invade deeper tissues?

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

    Which type of toxin degrades cytoplasmic membranes, causing cell lysis and death?

    <p>Cytolytic toxins</p> Signup and view all the answers

    Which component of bacteria are endotoxins part of?

    <p>The outer membrane of Gram-negative bacteria</p> Signup and view all the answers

    Which type of toxin is heat-stable?

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

    Which type of toxin is heat-labile?

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

    Which type of toxin is often highly toxic in small quantities?

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

    Which type of toxin is relatively poor in eliciting an immune response?

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

    Study Notes

    Bacterial Toxins and Their Mechanisms of Action

    • Infectious bacteria produce enzymes to breakdown the host’s tissues, such as hyaluronidase from Streptococcus pyogenes and collagenase from Clostridia.
    • Coagulase promotes blood clotting to block access to the bacteria, while streptokinase dissolves blood clots to invade deeper tissues.
    • Exotoxins are toxic proteins secreted by pathogens, including AB toxins, cytolytic toxins, and superantigen toxins.
    • Diphtheria toxin, an AB exotoxin, inhibits protein synthesis by catalyzing ADP-ribosylation of elongation factor EF-2.
    • Botulinum toxin from Clostridium botulinum inhibits muscle contraction by cleaving proteins involved in acetylcholine release.
    • Tetanus toxin from Clostridium tetanus floods neuromuscular junctions with acetylcholine, causing muscle contraction.
    • Cholera enterotoxin causes massive fluid secretion in the small intestine by activating adenylyl cyclase.
    • Cytolytic exotoxins degrade cytoplasmic membranes, causing cell lysis and death.
    • Endotoxins are part of the lipopolysaccharide component of the outer membrane of Gram-negative bacteria.
    • Exotoxins are heat-labile proteins, while endotoxins are extremely heat-stable lipopolysaccharide-lipoprotein complexes.
    • Exotoxins are often highly toxic in small quantities, while endotoxins are moderately toxic in larger amounts.
    • Exotoxins are immunogenic and can elicit an immune response, while endotoxins are relatively poor immunogens.

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    Related Documents

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    Description

    Test your knowledge of bacterial toxins and their mechanisms of action with this quiz. Explore how infectious bacteria produce enzymes to breakdown host tissues, the types of exotoxins and their effects, and the differences between exotoxins and endotoxins.

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