Microbiology STDs and Infections
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Questions and Answers

What role does slime production play in Staphylococcus epidermidis infections?

  • Causes faster replication of bacteria
  • Decreases host immune response
  • Increases susceptibility to antibiotics
  • Enhances attachment to devices like catheters (correct)
  • Which pathogen is the most common cause of community-acquired urinary tract infections in young females?

  • Escherichia coli
  • Staphylococcus aureus
  • Staphylococcus saprophyticus (correct)
  • Staphylococcus epidermidis
  • What type of coagulase is characteristic of coagulase-negative staphylococci (CoNS)?

  • Variable coagulase
  • Negative coagulase (correct)
  • Indeterminate coagulase
  • Positive coagulase
  • What is the novobiocin resistance pattern for Staphylococcus saprophyticus?

    <p>Resistant to novobiocin</p> Signup and view all the answers

    What is the virulence factor associated with Staphylococcus epidermidis that contributes to its pathogenicity?

    <p>Biofilm formation</p> Signup and view all the answers

    What distinguishes S. saprophyticus from S. epidermidis in a mannitol test?

    <p>S. saprophyticus is resistant to mannitol.</p> Signup and view all the answers

    In the Bacitracin susceptibility test, how do S. saprophyticus and S. epidermidis differ?

    <p>S. saprophyticus is resistant while S. epidermidis is sensitive.</p> Signup and view all the answers

    Which type of aerobe is S. saprophyticus classified as?

    <p>Facultative anaerobe</p> Signup and view all the answers

    Which test would yield a negative result for S. epidermidis?

    <p>Modified oxidase test</p> Signup and view all the answers

    What is the glucose utilization characteristic of S. saprophyticus?

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

    How does S. epidermidis respond to the Furazolidone/Furoxone susceptibility test?

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

    What is the hemolytic activity of S. saprophyticus on Blood Agar Plates (BAP)?

    <p>Gamma hemolytic or non-hemolytic</p> Signup and view all the answers

    Which statement about the modified oxidase test for S. saprophyticus is true?

    <p>It is negative for both S. saprophyticus and S. epidermidis.</p> Signup and view all the answers

    What is the primary virulence factor of Neisseria meningitidis?

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

    Which of the following organisms is primarily responsible for causing gonorrhea?

    <p>Neisseria gonorrhoeae</p> Signup and view all the answers

    What is the consequence of untreated gonococcal infections in newborns?

    <p>Ophthalmia neonatorum</p> Signup and view all the answers

    What type of specimen is recommended for collecting samples to test for gonorrhea?

    <p>Dacron or rayon swab</p> Signup and view all the answers

    Which of the following sugars does Moraxella catarrhalis ferment?

    <p>Maltose and glucose</p> Signup and view all the answers

    Which test is used to indicate the presence of Neisseria meningitidis?

    <p>Neufeld Quellung Test</p> Signup and view all the answers

    What type of colonies does N. sicca produce when cultured?

    <p>Breadcrumbs like colonies</p> Signup and view all the answers

    What is a characteristic feature of Moraxella catarrhalis's natural habitat?

    <p>Oro and nasopharynx</p> Signup and view all the answers

    What is the primary hemolysis pattern exhibited by Streptococcus pyogenes on Blood Agar Plates (BAP)?

    <p>Beta hemolysis</p> Signup and view all the answers

    Which virulence factor of Streptococcus pyogenes is primarily responsible for its anti-phagocytic properties?

    <p>M protein</p> Signup and view all the answers

    Which clinical condition is NOT caused by Streptococcus pyogenes?

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

    What characteristic feature does the erythrogenic toxin of Streptococcus pyogenes cause?

    <p>Rashes in scarlet fever</p> Signup and view all the answers

    Which characteristic distinguishes Streptococcus pyogenes from other Streptococci in the Lancefield classification?

    <p>Group A carbohydrate</p> Signup and view all the answers

    What laboratory test would most likely be used to detect a Streptococcus pyogenes infection?

    <p>ASO test</p> Signup and view all the answers

    What type of hemolysin is Streptolysin O classified as?

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

    What is a common post-streptococcal sequelae associated with repeated pharyngitis?

    <p>Rheumatic fever</p> Signup and view all the answers

    What is the percentage of O2 required for aerobes?

    <p>21%</p> Signup and view all the answers

    Which test is used to detect micrococci?

    <p>Oxidase Test with 6% oxidase reagent</p> Signup and view all the answers

    What color indicates a positive result for the cytochrome test?

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

    Which species is a late lactose fermenter detected by the ONPG test?

    <p>N.lactamica</p> Signup and view all the answers

    What are the CO2 requirements for capnophilic organisms?

    <p>5-10%</p> Signup and view all the answers

    Which species has a positive result for glucose but negative for all other sugars?

    <p>N.gonorrhea</p> Signup and view all the answers

    What does a positive oxidase test result indicate when using a 1% oxidase reagent?

    <p>Presence of Gram-negative bacteria</p> Signup and view all the answers

    Which organism is positive for glucose and maltose but negative for lactose, sucrose, and fructose?

    <p>N.meningitidis</p> Signup and view all the answers

    Study Notes

    Gonorrhea

    • Gonorrhea is a sexually transmitted disease (STD).
    • In females, a cervical swab is used for specimen collection.
    • In males, a urethral swab is used for specimen collection.
    • Gonorrhea can cause opthalmia neonatorum, a gonococcal eye infection in newborns.
    • Opthalmia neonatorum is acquired when discharge from an infected mother accumulates in the newborn's conjunctiva.
    • Crede's prophylaxis or erythromycin is used to prevent opthalmia neonatorum.

    Neisseria meningitidis

    • Neisseria meningitidis is a gram-negative diplococcus.
    • Neisseria meningitidis is encapsulated.
    • The Quellung Test is positive for Neisseria meningitidis.
    • The Neufeld Quellung Test detects the presence of a bacterial capsule through agglutination.

    Moraxella catarrhalis

    • Moraxella catarrhalis is a gram-negative diplococcus.
    • Moraxella catarrhalis is oxidase positive.
    • Moraxella catarrhalis ferments maltose and glucose.
    • Moraxella catarrhalis is a common inhabitant of the oro and nasopharynx.
    • Moraxella catarrhalis is nonencapsulated.

    Staphylococcus

    • Staphylococcus is a facultative anaerobe.
    • Staphylococcus is catalase positive.

    Micrococcus

    • Micrococcus is a strict aerobe.
    • Micrococcus is catalase positive.

    Staphylococcus saprophyticus

    • Staphylococcus saprophyticus is resistant to novobiocin.
    • Staphylococcus saprophyticus is the most common cause of urinary tract infections (UTI) in young females.
    • Staphylococcus saprophyticus causes pyelonephritis and cystitis in patients with indwelling catheters.

    Staphylococcus epidermidis

    • Staphylococcus epidermidis is sensitive to novobiocin.
    • Staphylococcus epidermidis is a normal skin flora.
    • Staphylococcus epidermidis causes UTIs, stitch abscesses, and prosthetic heart valve infections.

    CoNS

    • CoNS stands for coagulase-negative staphylococci.
    • CoNS is a common inhabitant of the human skin.
    • CoNS are coagulase negative.
    • CoNS are mannitol fermentation negative.
    • CoNS are DNase negative.
    • CoNS do not produce hemolysis (gamma hemolysis).
    • The main virulence factor for CoNS is slime production and biofilm formation, which promotes adherence to plastic catheters.

    Streptococcus pyogenes

    • Streptococcus pyogenes is a gram-positive cocci.
    • Streptococcus pyogenes is catalase negative.
    • Streptococcus pyogenes is PYR positive.
    • Streptococcus pyogenes is bacitracin-susceptible.
    • Streptococcus pyogenes belongs to Lancefield Group A.
    • Streptococcus pyogenes is a major throat pathogen and is associated with bacterial pharyngitis (strep throat).
    • Streptococcus pyogenes causes pyoderma, a skin infection that can be characterized by erysipelas.
    • Streptococcus pyogenes also causes scarlet fever, characterized by a strawberry tongue.
    • Streptococcus pyogenes can cause necrotizing fasciitis, a rapid-progressing skin infection.
    • Streptococcus pyogenes is associated with post streptococcal sequelae, such as acute glomerulonephritis and rheumatic fever.

    Streptococcus pyogenes virulence factors

    • M-protein (found in the cell wall) - major virulence factor; anti-phagocytic
    • Protein F - Promotes attachment to epithelial cells
    • Streptokinase - Dissolves clots, promotes fibrinolysis
    • Hyaluronidase - Spreading factor
    • Erythrogenic or pyrogenic toxin - Causes rashes in scarlet fever
    • Streptolysin O - Oxygen labile, antigenic, responsible for beta hemolysis
    • Streptolysin S - Causes sub-surface hemolysis on blood agar plates

    Virulence factor for Staphylococcus aureus

    • Protein A - Promotes attachment to epithelial cells
    • Staphylokinase - Promotes fibrinolysis

    Hemolysis on Blood Agar Plates (BAP)

    • Gamma hemolysis: No hemolysis
    • Beta hemolysis: Clear zone around colony
    • Alpha hemolysis: Greenish discoloration around colony

    Lancefield Classification of Streptococci

    • Based on the presence of cell wall polysaccharides (common C carbohydrate)

    ONPG Test

    • Used to detect late lactose fermenters (Lactose Negative, ONPG Positive)

    Oxidase Test

    • Modified oxidase test - Detects micrococci (G+) using 6% oxidase reagent, resulting in a blue color.
    • Cytochrome oxidase test - Detects gram-negative organisms using 1% oxidase reagent resulting in a purple color.

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    Description

    This quiz covers key information about sexually transmitted diseases, focusing on gonorrhea, as well as bacterial pathogens like Neisseria meningitidis and Moraxella catarrhalis. Test your knowledge on their characteristics, specimen collection methods, and associated complications. Perfect for students seeking to understand clinical microbiology.

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