Microbiology Chapter 5: Bacterial Skin Infections
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Questions and Answers

What is the primary role of Toxic Shock Syndrome Toxin-1 (TSST-1)?

  • To stimulate T-cell proliferation (correct)
  • To degrade sphingomyelin
  • To cause generalized desquamation
  • To affect erythrocytes and leukocytes
  • Which type of exfoliative toxin is encoded by the eta gene?

  • Exfoliative toxin C
  • Toxic shock syndrome toxin
  • Exfoliative toxin B
  • Exfoliative toxin A (correct)
  • Alpha-hemolysin is known to primarily affect which type of blood cells?

  • Platelets
  • Neutrophils
  • Lymphocytes
  • Erythrocytes (correct)
  • Panton-Valentine Leukocidin (PVL) specifically targets which type of leukocytes?

    <p>Polymorphonuclear leukocytes</p> Signup and view all the answers

    What is a common effect of the serine protease known as exfoliative toxin?

    <p>Generalized desquamation of the skin</p> Signup and view all the answers

    Which hemolysin is primarily responsible for damaging smooth muscle in blood vessels?

    <p>Alpha-hemolysin</p> Signup and view all the answers

    Which type of exfoliative toxin is described as heat-labile?

    <p>Exfoliative toxin B</p> Signup and view all the answers

    Which hemolysin is particularly noted for its role in producing diarrhea during gastrointestinal infections?

    <p>Delta-hemolysin</p> Signup and view all the answers

    What is the primary reservoir for Staphylococci?

    <p>Human Nares</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Staphylococci?

    <p>Motile and spore-forming</p> Signup and view all the answers

    What is a major virulence factor associated with Staphylococcus aureus that can contribute to Toxic Shock Syndrome?

    <p>Toxic Shock Syndrome Toxin-1</p> Signup and view all the answers

    Which of the following skin diseases is caused by Staphylococcus aureus?

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

    Which of these Staphylococcal virulence factors involves the formation of blood clots?

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

    How are most Staphylococcal infections primarily transmitted?

    <p>Direct contact with lesions</p> Signup and view all the answers

    Which of the following is true regarding the oxygen requirements of Staphylococci?

    <p>Aerobic or facultative anaerobic</p> Signup and view all the answers

    What type of diagnostic tests are typically used for identifying Staphylococci?

    <p>Blood cultures and sensitivity tests</p> Signup and view all the answers

    Study Notes

    Staphylococci Overview

    • Gram-positive spherical cells arranged in grape-like clusters.
    • Can be aerobic or facultative anaerobic; non-motile and non-spore forming.
    • Produce catalase as a by-product; normal flora of skin and mucous membranes.
    • Primary human reservoir located in the nares.

    Virulence Factors of Staphylococci

    • Toxic Shock Syndrome Toxin-1 (TSST-1):

      • Superantigen that stimulates T-cell proliferation and cytokine production.
      • Associated with fever and shock; found in approximately 20% of S. aureus isolates.
      • Primarily linked to menstruation-associated toxic shock syndrome.
    • Exfoliative Toxins:

      • Serine proteases causing epidermal desquamation.
      • Includes Exfoliative toxin A (heat-stable) and toxin B (heat-labile).
      • Major contributor to Staphylococcal Scalded Skin Syndrome (SSSS), especially in newborns.
    • Hemolysins:

      • Cytolytic toxins targeting erythrocytes (RBCs) and leukocytes (WBCs).
      • Four types identified: alpha, beta, delta, and gamma hemolysins.
      • Alpha-hemolysin is involved in tissue damage and vascular disruption.
    • Panton-Valentine Leukocidin (PVL):

      • Lethal exotoxin specifically affecting polymorphonuclear leukocytes.
      • Associated with severe skin and soft tissue infections.

    Staphylococcus aureus Infections

    • Causes various skin conditions such as folliculitis, furuncles, carbuncles, bullous impetigo, SSSS, and toxic shock syndrome.

    Diagnostic Laboratory Tests for Staphylococci

    • Tests to identify the presence and characteristics of Staphylococcus spp. in clinical samples.

    Epidemiology and Control of Staphylococci

    • Focus on understanding transmission, risk factors, and strategies for infection prevention and control.

    Streptococci Overview

    • Classification includes various groups, each associated with specific virulence factors and skin diseases.

    Bacillus Overview

    • Includes Bacillus anthracis as notable species with significant virulence factors leading to specific diseases.

    Clostridium Overview

    • General characteristics and virulence factors of Clostridium, particularly Clostridium perfringens, and the associated diseases they cause.

    Erysipelothrix

    • Erysipelothrix rhusiopathiae is highlighted, focusing on its characteristics and implications.

    Mycobacterial Skin Infections

    • Introduces Mycobacterium leprae, Mycobacterium marinum, and Mycobacterium ulcerans with their respective pathogenic roles and clinical manifestations.

    Summary Insights

    • Review of key bacterial pathogens responsible for skin infections, their virulence mechanisms, diagnostic approaches, and infection control strategies.

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    Quiz Team

    Description

    This quiz covers vital concepts from Module 5 on bacterial skin infections, focusing on Staphylococci and Streptococci. Learn about their characteristics, virulence factors, and diagnostic methods. Understand the epidemiology and control measures associated with these bacteria.

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