Bacteriology Lecture: Gram + Bacilli Part 2
41 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What characteristic morphology does the organism exhibit on a 5% Sheep’s Blood Agar?

  • Flat, brown colonies
  • Large, mucoid colonies
  • Small, white, translucent colonies (correct)
  • Small, red colonies
  • Which antimicrobial is the organism resistant to?

  • Erythromycin
  • Amoxicillin
  • Cephalosporin (correct)
  • Vancomycin
  • What type of oxygen environment does the organism thrive in?

  • Microaerophilic (correct)
  • Facultative anaerobic
  • Aerobic
  • Obligate anaerobic
  • What is the expected result of a Gram stain of the organism?

    <p>Gram-positive bacilli</p> Signup and view all the answers

    Which culture medium is specifically mentioned for diagnosing the organism?

    <p>McBride Agar</p> Signup and view all the answers

    Which of the following statements about the organism's ability to survive is accurate?

    <p>It can survive within phagocytes</p> Signup and view all the answers

    What type of hemolysis is observed on Sheep’s Blood Agar?

    <p>Narrow band of beta hemolysis</p> Signup and view all the answers

    What virulence factor allows Listeria to escape the phagolysosome?

    <p>Listeriolysin O</p> Signup and view all the answers

    At what temperature can motility be observed to differentiate L. monocytogenes from Corynebacterium?

    <p>25 degrees C</p> Signup and view all the answers

    Which of the following conditions can be caused by Listeria monocytogenes?

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

    What is the outcome of refrigeration of Listeria for several months?

    <p>Enhanced virulence</p> Signup and view all the answers

    What is the purpose of Loeffler’s Medium in the culture of Corynebacterium diphtheriae?

    <p>To stimulate the growth of C. diphtheriae &amp; production of metachromatic granules</p> Signup and view all the answers

    How does the Reverse CAMP Test indicate the presence of Corynebacterium pseudotuberculosis?

    <p>Through the formation of a bowtie appearance</p> Signup and view all the answers

    What differentiates Listeria from other bacteria in laboratory cultures?

    <p>Growth on Tomato Juice Agar</p> Signup and view all the answers

    What does Shick’s Test assess in relation to Corynebacterium diphtheriae?

    <p>The susceptibility of the individual to diphtheria</p> Signup and view all the answers

    Which factor contributes to the transmission of listeriosis in humans?

    <p>Ingestion of contaminated food</p> Signup and view all the answers

    Which serum is commonly used in thioglycollate broth to enhance the growth of lipophilic coryneform bacteria?

    <p>Rabbit serum</p> Signup and view all the answers

    What type of hemolysis is exhibited by Listeria monocytogenes?

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

    What is indicated by a positive result in the in vivo toxigenicity test using guinea pigs?

    <p>Indication of high virulence potential</p> Signup and view all the answers

    Which of the following is considered a common consequence of listeriosis?

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

    Which method is utilized for in vitro toxigenicity testing of Corynebacterium species?

    <p>Modified Elek’s Test</p> Signup and view all the answers

    What type of bacteria is primarily targeted through the culture process on CTBA after initial subculture?

    <p>Corynebacterium diphtheriae</p> Signup and view all the answers

    In what conditions should the Reverse CAMP Test be incubated for accurate results?

    <p>At 37 degrees Celsius for 24-48 hours in aerobic conditions</p> Signup and view all the answers

    What is a characteristic of the Corynebacterium diphtheriae's club-shaped appearance?

    <p>Swollen one end</p> Signup and view all the answers

    Which biotype of Corynebacterium diphtheriae is associated with non-hemolytic characteristics?

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

    What type of toxin does Corynebacterium diphtheriae produce?

    <p>Heat-labile exotoxin</p> Signup and view all the answers

    What is the primary method of transmission for the respiratory form of diphtheria?

    <p>Droplet infection</p> Signup and view all the answers

    Which medium is specifically used for enhancing the growth of Corynebacterium diphtheriae?

    <p>Reco medium</p> Signup and view all the answers

    How does the cutaneous form of diphtheria typically present itself?

    <p>Slow healing ulcers and membranous formation</p> Signup and view all the answers

    What gram stain reaction does Corynebacterium diphtheriae exhibit?

    <p>Gram-positive bacilli</p> Signup and view all the answers

    What is the main pathogenic sign of Corynebacterium diphtheriae infection?

    <p>Pseudomembrane formation in tonsils</p> Signup and view all the answers

    Which of the following is a commonly used agar for identifying Corynebacterium diphtheriae?

    <p>Tinsdale Medium</p> Signup and view all the answers

    What is the appearance of colonies on Cystine Tellurite Blood Agar for Corynebacterium diphtheriae?

    <p>Gun metal black colonies</p> Signup and view all the answers

    What type of bacteria is Erysipelothrix rhusiopatiae?

    <p>Gram + bacilli</p> Signup and view all the answers

    Which of the following statements about Erysipelothrix rhusiopatiae is true?

    <p>It can cross the placenta.</p> Signup and view all the answers

    What is the typical motility characteristic of Erysipelothrix rhusiopatiae?

    <p>Tumbling motility</p> Signup and view all the answers

    In which test does Erysipelothrix rhusiopatiae show a positive result?

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

    How does Erysipelothrix rhusiopatiae typically grow on agar?

    <p>Umbrella-like growth</p> Signup and view all the answers

    Which of the following environments can Erysipelothrix rhusiopatiae survive in?

    <p>High salt concentrations</p> Signup and view all the answers

    What disease is commonly associated with Erysipelothrix rhusiopatiae?

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

    What is the Gram stain result for Erysipelothrix rhusiopatiae?

    <p>Gram + bacilli</p> Signup and view all the answers

    Study Notes

    Bacteriology Overview

    • Hemolytic and starch/glycogen tests yield negative results with a bleach-like odor.

    Corynebacterium diphtheriae

    • Gram-positive bacilli, highly pleomorphic; often club and rod-shaped.
    • Ferments dextrose and glucose; utilizes starch/glycogen (+).
    • Metachromatic granules (Babes-Ernst granules) are distinctive.
    • Biotypes include:
      • Intermedius: small, dry gray/black colonies with a gray border.
      • Gravis: largest colonies with a daisy head appearance, non-hemolytic.
      • Belfanti: most frequently recovered, associated with severe infections.
    • Toxigenic strains produce diphtheria exotoxin (heat labile A and B components).
    • Clinical infections include:
      • Respiratory form: pharyngitis with pseudomembranous covering and systemic effects on heart and nerves.
      • Cutaneous form: characterized by slow healing ulcers and membranous formations.
    • Culture media:
      • Tinsdale Medium for black colonies with brown halos.
      • Loeffler's Serum Slant for poached-egg colonies.
      • Cystine Tellurite Blood Agar (CTBA) for gray-black colonies.

    Laboratory Diagnosis

    • Nasopharyngeal and throat swabs are collected using Dacron Tipped Swab or Calcium Alginate.
    • Cultures are performed on 5% Sheep’s Blood Agar, Chocolate Agar, and anaerobic BAP.
    • Tests for motility, Gram stain, and various ferments (glucose, maltose, sucrose, mannitol) provide identification.
    • Toxigenicity testing includes:
      • In Vivo Toxigenicity (guinea pig lethality test).
      • In Vitro (Modified Elek’s Test for immunodiffusion).

    Erysipelothrix rhusiopathiae

    • Small Gram-positive coccobacilli, not part of normal flora (NF), and animal pathogens.
    • Possesses tumbling motility and resistant to salty, pickled conditions.
    • Associated with erysipeloid infections, especially in handlers or farmers.
    • Gram stain shows alpha hemolytic characteristics on BAP.
    • Can grow in refrigerated conditions for extended periods; isolated from crustaceans, ticks, and fleas.

    Other Bacterial Infections

    • Differential tests for Listeria monocytogenes, significant for foodborne illnesses and meningitis:
      • Motility at 25°C and unique salicin fermentation test.
    • Listeria virulence factors include Listeriolysin O and superoxide dismutase for survival and evasion mechanisms.
    • Lactobacillus acidophilus is a non-pathogenic resident of the GI tract, produces lactic acid to combat urogenital infections.
    • Notable for fermentation properties and importance in food products (e.g., yogurt).

    Diagnostic Features

    • Shick’s Test assesses susceptibility to diphtheria.
    • Reverse CAMP test clarifies distinctions between bacterial species.
    • Cultures and biochemical tests reveal significant traits for identification and environmental survival.

    Summary

    • Understanding the characteristics and laboratory diagnostics of Corynebacterium diphtheriae and Erysipelothrix rhusiopathiae is essential in clinical microbiology, particularly for differentiating pathogenic bacteria and managing infections.

    Studying That Suits You

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

    Quiz Team

    Related Documents

    Gram+ Bacteria, Part 2 (PDF)

    Description

    This quiz covers key concepts in bacteriology, focusing on Gram-positive bacilli and specific characteristics of Corynebacterium diphtheriae. Test your understanding of colony morphology, hemolytic properties, and identifying features of bacteria. Ideal for students studying microbiology or related fields.

    More Like This

    Use Quizgecko on...
    Browser
    Browser