Microbiology Streptococci & Enterococci Quiz
12 Questions
102 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is true about Streptococci and Enterococci?

  • They occur in clusters
  • They lack the enzyme catalase (correct)
  • They are motile
  • They are anaerobes

    • What is Beta Hemolysis?

    Complete lysis of RBCs around a colony, resulting in a clear zone surrounding the colonies.

    What is Alpha Hemolysis?

    Partial breakdown of the hemoglobin inside RBCs, producing a green discoloration around the colonies.

    Define Gamma Hemolysis.

    <p>No hemolysis of blood; no effect on RBCs.</p> Signup and view all the answers

    What is the significance of Group A Streptococci?

    <p>serious human pathogen, primarily found in the pharynx, causes multiple infections.</p> Signup and view all the answers

    What infections are associated with Group B Streptococci?

    <p>Neonatal infection like sepsis and meningitis, as well as access, endocarditis, septicemia.</p> Signup and view all the answers

    What are the characteristics of Alpha Hemolytic Group: Streptococcus pneumoniae?

    <p>Does not possess a Lancefield antigen and is causative agent of pneumonia.</p> Signup and view all the answers

    What is the function of the CAMP test?

    <p>It helps identify Streptococcus agalactiae.</p> Signup and view all the answers

    What distinguishes humans as carriers of Staphylococci and Streptococci?

    <p>Staphylococci occur in clusters and are catalase positive; Streptococci occur in chains and are catalase negative.</p> Signup and view all the answers

    What is the appearance difference between S.agalactiae and S.pyrogenes on blood agar?

    <p>S.agalactiae colonies are large with a narrow zone of beta hemolysis; S.pyrogenes have small colonies with a large zone of beta hemolysis.</p> Signup and view all the answers

    What streptococcal species is investigated in third trimester pregnant women?

    <p>S.agalactiae (group B strep).</p> Signup and view all the answers

    Which streptococci are implicated in dental caries?

    <p>Viridans streptococci, such as S.mutans.</p> Signup and view all the answers

    Study Notes

    Streptococci & Enterococci Overview

    • Streptococci and enterococci are primarily found in chains and are Gram-positive bacteria.
    • They are facultative anaerobes, nonmotile, and lack catalase.

    Hemolysis Types

    • Beta Hemolysis: Complete lysis of red blood cells (RBCs) creates a clear zone around colonies.
    • Alpha Hemolysis: Partial breakdown of hemoglobin in RBCs results in a green discoloration around colonies.
    • Gamma Hemolysis: No hemolysis occurs, with no effect on RBCs.

    Beta Hemolytic Groups

    • Group A Streptococci (S. pyrogenes): Most serious, primarily found in the pharynx, skin, and rectum; produces hemolysins causing complete lysis of RBCs.
    • Group B Streptococci (S. agalactiae): Common in the genital and intestinal tracts; significant neonatal infections including sepsis and meningitis. Identified by positive CAMP reaction.
    • Group C Streptococci (S. dysgalactiae): Uncommon pathogens; involved in pharyngitis and endocarditis, differentiated by Bacitracin resistance and negative CAMP test.

    Alpha Hemolytic Groups

    • Streptococcus pneumoniae: Causes bacterial pneumonia, meningitis, and otitis media; virulent strains have a polysaccharide capsule and are positive for optochin susceptibility.
    • Viridans Streptococci: Opportunistic infections, associated with dental caries; appear small and grayish on blood agar, with negative bile esculin and variable salt tolerance test results.

    Enterococci Groups

    • Group D Enterococci (E. faecalis and E. faecium): Inhabit the GI tract and oral cavity; can cause urinary tract infections, bacteremia, and endocarditis. Show large non-hemolytic colonies.
    • Group D Nonenterococci (S. bovis): Present in the intestinal tract; associated with GI malignancies and can cause endocarditis.

    Sensitivity Tests

    • Optochin Sensitivity: Pneumococci are sensitive; viridans are resistant.
    • Bacitracin Sensitivity: S. pyrogenes is sensitive, while S. agalactiae is resistant.
    • SXT Sensitivity: Useful for identifying group C streptococci.

    Identification Tests

    • CAMP Test: Positive for S. agalactiae, indicating enhanced breakdown of RBCs.
    • Lancefield Antigen Testing: Differentiates between streptococcal groups based on carbohydrate antigens.
    • NaCl Tolerance Test: Distinguishes enterococci from other group D streptococci.
    • SXT Test: Group A strep is resistant, while group C is sensitive.

    Clinical Applications

    • Throat Swab on Blood Agar: Stabbing creates anaerobic conditions, improving hemolysis development.
    • Pregnant Women Screening: Focus on S. agalactiae (group B strep) status during the third trimester.
    • Dental Caries Development: Caused by viridans streptococci like S. mutans fermenting sugars and producing enamel-eroding acids.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Test your knowledge on Streptococci and Enterococci with this informative quiz designed specifically for microbiology students. Covering important concepts such as hemolysis and characteristics of these bacteria, this quiz helps reinforce your understanding of gram-positive microorganisms.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser