Enterobacteriaceae Family Quiz
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Questions and Answers

What characteristic distinguishes motile bacteria from non-motile bacteria during growth in a medium?

  • Motile bacteria produce sharply defined margins.
  • Motile bacteria form dense colonies at the stab-line.
  • Motile bacteria spread throughout the medium, creating a hazy appearance. (correct)
  • Motile bacteria create transparent zones around colonies.

    • In which medium do all Vibrio species remain immobilized?

  • Nutrient agar
  • Sterile distilled water (correct)
  • Sulfide Indole Motility medium
  • Peptone water

    • What does the Methyl Red (MR) test evaluate in microbes?

  • Mixed acids fermentation when glucose is available (correct)
  • Indole formation capabilities
  • Hydrogen sulfide production
  • Lactose fermentation capacity

    • Which of the following characteristics can help differentiate various genera of enteric bacteria?

    <p>Fermentation product types and proportions</p> Signup and view all the answers

    What role does the Sulfide Indole Motility (SIM) Medium serve in bacterial identification?

    <p>It determines hydrogen sulfide production, indole formation, and motility.</p> Signup and view all the answers

    What type of metabolism is exhibited by Proteus species?

    <p>Fermentative and respiratory type metabolism</p> Signup and view all the answers

    Which of the following media is recommended for the selective isolation of microbes?

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

    What positive biochemical reaction is characteristic of Morganella morganii?

    <p>Methyl-Red</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the genus Morganella?

    <p>Lactose fermenting</p> Signup and view all the answers

    What is the macroscopic appearance of Providencia spp. on enteric agars?

    <p>Dull gray colonies, non-swarming</p> Signup and view all the answers

    Which of the following reactions does Morganella morganii exhibit?

    <p>Ornithine decarboxylase positive</p> Signup and view all the answers

    What type of microorganisms are primarily associated with the genus Morganella?

    <p>Intestinal and feces pathogens</p> Signup and view all the answers

    Which of the following is a negative biochemical reaction seen in Morganella?

    <p>Gas production from mannose</p> Signup and view all the answers

    What substance is used as an indicator for acidification in the TSI Agar test?

    <p>Phenol red</p> Signup and view all the answers

    A tube showing an alkaline slant and an acidic butt (K/A) indicates what type of fermentation?

    <p>Glucose fermentation only</p> Signup and view all the answers

    What will happen to the TSI Agar if both lactose and sucrose are fermented?

    <p>Both butt and slant will turn yellow</p> Signup and view all the answers

    Under what condition does ammonia get produced during the TSI Agar test?

    <p>When peptone is utilized under aerobic conditions</p> Signup and view all the answers

    In the TSI test, what does a red/red result signify?

    <p>Glucose, lactose, and sucrose non-fermenter</p> Signup and view all the answers

    What is the main role of peptone in the TSI Agar?

    <p>To serve as a nitrogen source</p> Signup and view all the answers

    Why is iron (ferrous sulfate) included in the TSI Agar?

    <p>As an indicator of H2S formation</p> Signup and view all the answers

    What color change occurs with potassium hydroxide in the TSI test?

    <p>From red to yellow</p> Signup and view all the answers

    What factor is primarily responsible for the attachment of ETEC to the intestinal mucosa?

    <p>Fimbrial protein CFA</p> Signup and view all the answers

    Which heat-stable toxin is most commonly associated with severe disease in ETEC infections?

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

    What is the typical incubation period for secretory diarrhea caused by ETEC?

    <p>1 to 2 days</p> Signup and view all the answers

    What characteristic distinguishes enteroaggregative E.coli (EAEC) from other strains?

    <p>Stacked-brick arrangement over the intestinal epithelium</p> Signup and view all the answers

    Which of the following symptoms is least commonly associated with ETEC infections?

    <p>Bloody diarrhea</p> Signup and view all the answers

    What is the prevalence of disease caused by EAEC primarily constrained by?

    <p>Absence of a single molecular marker</p> Signup and view all the answers

    Which of the following is a heat-labile enterotoxin produced by ETEC strains?

    <p>LT-I</p> Signup and view all the answers

    In which group of individuals is the mortality rate from ETEC infections particularly high?

    <p>Children and the elderly</p> Signup and view all the answers

    Which metabolic property is associated with Providencia species?

    <p>Facultatively anaerobic</p> Signup and view all the answers

    What is the most common habitat for Providencia stuartii and Providencia rettgeri infections?

    <p>Urinary tract</p> Signup and view all the answers

    Which of the following is a recommended media for selective isolation of Providencia?

    <p>Simmons Citrate Agar</p> Signup and view all the answers

    Which biochemical reaction is positive for Providencia species except for Providencia heimbachae?

    <p>Indole production</p> Signup and view all the answers

    Which of the following species is associated with wound and burn infections?

    <p>Providencia stuartii</p> Signup and view all the answers

    What type of metabolism do Providencia species exhibit?

    <p>Fermentative and respiratory type metabolism</p> Signup and view all the answers

    Which of the following reactions can be described as positive for Providencia species?

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

    What is the recommended method for long-term storage of Providencia species?

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

    What type of infections is Hafnia alvei commonly associated with?

    <p>Infections in patients with underlying illnesses</p> Signup and view all the answers

    Which of the following media is recommended for the selective isolation of Hafnia alvei?

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

    Which biochemical reaction is positive for Hafnia alvei?

    <p>Lysine decarboxylase</p> Signup and view all the answers

    What is the primary habitat of Hafnia alvei?

    <p>Sewage and natural environments</p> Signup and view all the answers

    Which of the following is a negative biochemical reaction for Hafnia alvei?

    <p>H2S production in TSI</p> Signup and view all the answers

    Hafnia alvei is primarily classified under which category in terms of pathogenicity?

    <p>Opportunistic pathogens</p> Signup and view all the answers

    What is the Gram stain result for Hafnia alvei?

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

    What is the size range for Hafnia alvei cells?

    <p>1.0 to 5.0 micrometers</p> Signup and view all the answers

    Study Notes

    Enterobacteriaceae Family

    • A large group of bacteria, biochemically and genetically related
    • Traditional bacteria found in this family include Escherichia, Shigella, Salmonella, Enterobacter, Proteus, and Yersinia
    • Gram-negative, short rods
    • Non-sporulating, facultative anaerobes
    • Simple nutritional requirements

    Common Characteristics

    • Gram-negative, short rods
    • Non-sporulating, facultative anaerobes
    • Simple nutritional requirements (isolate and differentiate on MacConkey Agar)
    • Lactose fermenters (pink colonies) and Non-lactose fermenters (pale colonies).
    • Cytochrome C oxidase negative
    • Usually reduces Nitrate to Nitrite
    • Contain enterobacterial common antigen (O, H, K, Vi)
    • Ferments glucose, producing acid from glucose
    • Not stimulated by sodium

    Biochemical Tests

    • Citrate utilization test:
      • Determines the ability to use citrate as a sole carbon source.
      • Alkaline conditions (blue color) indicate positive result; acidic conditions (no color change) indicate negative.
    • Indole test:
      • Determines the ability to split amino acid tryptophan.
      • Positive result with Kovacs' or Ehrlich's reagents: red compound
      • Negative result: no color change.
    • Motility test:
      • Determines the presence of peritrichous flagella.
      • Observe for diffuse, hazy growth throughout the medium (motile).
      • Non-motile strains will remain confined to the stab-line.
    • Methyl Red (MR) test:
      • Determines if the organism performs mixed acid fermentation when supplied glucose.
      • Acid production, lower pH, turns the medium red; Positive.
      • Less acid production, neutral pH, stays yellow; Negative.
    • Voges-Proskauer (VP) test:
      • Detects the ability to produce acetoin.
      • Positive: red color change after reagents added. Negative: No color change.
    • Triple Sugar Iron (TSI) agar test:
      • Identifies whether the bacteria can ferment glucose, lactose, and sucrose and whether they produce hydrogen sulfide.
      • Results are based on color changes in the slant and butt.
    • Urease test:
      • Measures the organism's ability to hydrolyze urea.
      • Positive tests turn a pink color.
    • Spot indole test:
      • For rapid identification of indole producers.

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    Description

    Test your knowledge on the Enterobacteriaceae family of bacteria. This quiz covers their common characteristics, biochemical tests, and notable members like Escherichia and Salmonella. Perfect for microbiology enthusiasts and students alike.

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