Microscopy and Catalase Test in Medical Bacteriology

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Questions and Answers

What does the catalase test determine?

  • The ability to hydrolyze urea
  • The ability to produce urease enzyme
  • The ability to degrade hydrogen peroxide (correct)
  • The ability to produce hydrogen peroxide

Which of the following organisms are catalase positive?

  • Escherichia coli
  • Streptococci (correct)
  • Enterococci
  • Klebsiella pneumoniae

What is the outcome when catalase-positive organisms are exposed to hydrogen peroxide?

  • Formation of a white precipitate
  • Production of bubbles (correct)
  • Color change of the agar
  • No visible change

Why is the production of catalase considered an important virulence factor?

<p>To counteract antimicrobial compounds (D)</p> Signup and view all the answers

In the catalase test, what is the key difference between staphylococci and streptococci?

<p>Catalase production (D)</p> Signup and view all the answers

How does the catalase test help differentiate between gram-positive organisms?

<p>Through the presence of catalase enzyme (D)</p> Signup and view all the answers

What is the purpose of the citrate test described in the text?

<p>To detect the ability of an organism to utilize citrate (A)</p> Signup and view all the answers

What enzyme is involved in breaking down citrate during the citrate utilization test?

<p>Citritase (B)</p> Signup and view all the answers

What color change indicates a positive result in the citrate test?

<p>Green to blue (B)</p> Signup and view all the answers

Which organism is given as an example for testing positive in the citrate test?

<p>Klebsiella pneumoniae (D)</p> Signup and view all the answers

How long does it take for a color change to deep blue or purple to occur in the oxidase test?

<p>10 seconds (A)</p> Signup and view all the answers

What is the purpose of using a petri dish in the catalase test?

<p>To prevent catalase aerosols from spreading. (A)</p> Signup and view all the answers

What does the motility test aim to determine?

<p>The ability of an organism to move using flagella (D)</p> Signup and view all the answers

How is the motility test performed?

<p>Stab once into semi-solid media with a straight needle (B)</p> Signup and view all the answers

What is the significance of observing the formation of bubbles against a dark background in the catalase test?

<p>To enhance readability and observation of the reaction. (D)</p> Signup and view all the answers

What is the source of electrons that the enzyme cytochrome c oxidase accepts during the oxidase test?

<p>Artificial substrates (A)</p> Signup and view all the answers

Why is the oxidase test used in microbiology?

<p>To identify organisms based on oxidase enzyme activity. (C)</p> Signup and view all the answers

What material is used to inoculate the filter paper or commercial disk in the oxidase test?

<p>Wooden stick (A)</p> Signup and view all the answers

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