Staphylococcus aureus Infections Quiz
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Questions and Answers

What is the primary role of δ hemolysin produced by S. aureus?

  • To cause injury to cells and leukocytes (correct)
  • To kill polymorphonuclear leukocytes
  • To promote phagocytosis
  • To facilitate the growth of bacteria

    • Furuncles are single lesions that do not progress into deeper tissues.

    False

    What bacterium is often associated with community-acquired skin infections and is known for producing Panton-Valentine leukocidin?

    S. aureus

    A __________ is an infection of the hair follicle.

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

    Match the following S. aureus infections with their descriptions:

    <p>Furuncle = A painful inflammation of the skin and subcutaneous tissue Carbuncle = Boils that have multiple lesions Bullous impetigo = Large pustules surrounded by a small zone of erythema Folliculitis = Infection of the hair follicle</p> Signup and view all the answers

    Which toxins are associated with staphylococcal food poisoning?

    <p>A, B, and D</p> Signup and view all the answers

    Toxic shock syndrome toxin-1 (TSST-1) is produced by the phage group II.

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

    What syndrome is caused by exfoliative toxin from S. aureus?

    <p>Scalded Skin Syndrome</p> Signup and view all the answers

    The primary reservoir of S. aureus is the ______.

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

    What type of activity is enhanced by β hemolysin?

    <p>Acts on sphingomyelin</p> Signup and view all the answers

    Match the following toxins of S. aureus with their effects:

    <p>Exfoliative toxin = Causes Scalded Skin Syndrome Toxin A = Associated with food poisoning TSST-1 = Causes toxic shock syndrome α hemolysin = Destroys platelets and tissues</p> Signup and view all the answers

    Name one mode of transmission for S. aureus.

    <p>Unwashed hands</p> Signup and view all the answers

    The three main types of hemolysins are α, β, and ______.

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

    What is the main effect of hyaluronidase in infections?

    <p>Spreads the infection by hydrolyzing hyaluronic acid</p> Signup and view all the answers

    Protein A negates the protective effects of immunoglobulin A (IgA).

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

    What syndrome is associated with severe exfoliative dermatitis?

    <p>Staphylococcal scalded skin syndrome (SSSS)</p> Signup and view all the answers

    The condition known as _________ is linked with the use of super-absorbent tampons.

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

    Match the following enzymes with their functions:

    <p>Coagulase = Diagnostic virulence factor Lipase = Breaks down fats and oils Hyaluronidase = Facilitates spread of infection Protein A = Blocks phagocytosis</p> Signup and view all the answers

    What is a potential consequence of Toxic Shock Syndrome?

    <p>Decreased hydration levels</p> Signup and view all the answers

    What duration do symptoms of Staphylococcal scalded skin syndrome typically last?

    <p>About 2 to 4 days</p> Signup and view all the answers

    Staphylococcus epidermidis is primarily responsible for community-acquired infections.

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

    Which of the following is a mode of transmission for Aureus?

    <p>Traumatic introduction</p> Signup and view all the answers

    Micrococcus luteus produces acid under anaerobic conditions in glucose O/F media.

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

    What antibiotic is used to treat infections caused by Methicillin-resistant Staphylococci?

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

    Chronic infections, indwelling devices, and immune response defects are examples of __________ conditions that predispose individuals to Aureus infections.

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

    Match the following types of MRSA with their characteristics:

    <p>HA-MRSA = Health care-associated MRSA that poses serious threats to health institutions HACO-MRSA = Community-associated MRSA often found in healthy individuals</p> Signup and view all the answers

    Which method is recommended to determine methicillin resistance in staphylococci?

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

    Vancomycin-resistant Staphylococcus aureus (VRSA) was first isolated in the United States in 2007.

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

    What gene is associated with methicillin resistance in Staphylococcus aureus?

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

    The gold standard for identifying methicillin-resistant Staphylococcus aureus is the __________ test.

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

    Match the identification methods with their descriptions:

    <p>Real-time PCR = Identifies MRSA and MSSA BBL staphyloslide = Rapid identification of S. aureus Qualitative nucleic acid hybridization = Targets rRNA sequences MALDI-TOF = Mass spectrometry for bacterial identification</p> Signup and view all the answers

    Which of the following statements is true regarding macrolide resistance?

    <p>Resistance patterns for erythromycin and clindamycin should be the same</p> Signup and view all the answers

    Only a small fraction of the population of methicillin-resistant Staphylococcus aureus express the phenotype despite having the genetic potential.

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

    What does the mecA gene encode?

    <p>Penicillin-binding proteins</p> Signup and view all the answers

    Study Notes

    Pus Formers

    • Hot-cold lysin operates optimally at 37°C; effectiveness is maintained when stored at 4°C.
    • Furuncle (boil): painful skin inflammation affecting the skin and subcutaneous tissue.
    • Carbuncles: multiple localized lesions that may penetrate deeper tissues than a single boil.

    Infections Caused by S. aureus

    • Skin and wound infections include:
      • Folliculitis: infection of the hair follicle.
      • Bullous impetigo: large pustules with surrounding redness; highly contagious, spreading via direct contact and fomites.

    Virulence Factors of S. aureus

    • Exotoxins include enterotoxins causing diarrhea and vomiting; heat-stable, resistant to gastric acid.
    • Toxic Shock Syndrome Toxin-1 (TSST-1) is a superantigen resulting in toxic shock syndrome.
    • Exfoliative toxin (epidermolytic toxin): causes sloughing of the epidermal layer, linked to Scalded Skin Syndrome (SSS) and bullous impetigo.
    • Hemolysins: three main types (α, β, δ); α hemolysin destroys platelets and tissues, while β hemolysin enhances activity against RBC membranes.

    Enzymes in S. aureus

    • Coagulase: diagnostic marker, unclear role in virulence.
    • Hyaluronidase: hydrolyzes hyaluronic acid, facilitating the spread of infection.
    • Lipase: breaks down fats and oils of sebaceous glands.

    Protein A

    • Binds to the Fc portion of antibodies, evading phagocytosis, and negating immunoglobulin G (IgG) protective effects.

    Toxic Shock Syndrome

    • Linked to super-absorbent tampons with symptoms including high fever, rash, watery diarrhea, and vomiting leading to dehydration and hypotension.
    • Transmission via needle sticks, skin destruction, and medical procedures.

    Epidemiology of S. aureus

    • Primary reservoir: nasal passages (nares); other reservoirs include axillae, vagina, and skin surfaces.
    • Hospital outbreaks frequently occur in nurseries, burn units, and among surgical patients.
    • Transmitted through unwashed hands and fomites.

    Scalded Skin Syndrome

    • Extensive exfoliative dermatitis; more common in patients with renal failure and the immunocompromised.
    • Severity varies, lasting 2 to 4 days, with a potential for spontaneous recovery in children, but adult cases may be fatal.

    Methicillin-Resistant Staphylococci (MRSA)

    • HACO-MRSA and HA-MRSA represent health care-associated and hospital-associated strains, respectively, posing significant health threats.
    • Infection control measures include barrier protection, contact isolation, and handwashing.
    • Treatment primarily involves vancomycin with susceptibility tested via cefoxitin.

    Rapid Identification Methods

    • BBL staphyloslide, Staphaurex®, and BactiStaph® are used for identifying MRSA.
    • Real-time PCR and qualitative nucleic acid hybridization assays target staphylococcal identification from blood cultures.
    • Gold standard: mecA gene detection via PCR for identifying MRSA.

    Vancomycin-Resistant Staphylococci

    • VRSA and VISA emerged in the U.S. in 2002, indicating increased antibiotic resistance challenges.

    Macrolide Resistance

    • Resistance patterns to clindamycin may not be immediately evident; erythromycin and clindamycin should show the same resistance patterns.

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    Description

    Test your knowledge on Staphylococcus aureus and its associated infections. This quiz covers δ hemolysin, community-acquired skin infections, and various types of lesions produced by this bacterium. Match infections with their descriptions to enhance your understanding of S. aureus pathology.

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