Microscopy and Catalase Test in Medical Bacteriology

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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?

To counteract antimicrobial compounds Signup and view all the answers

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

Catalase production Signup and view all the answers

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

Through the presence of catalase enzyme Signup and view all the answers

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

To detect the ability of an organism to utilize citrate Signup and view all the answers

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

Citritase Signup and view all the answers

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

Green to blue Signup and view all the answers

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

Klebsiella pneumoniae 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?

10 seconds Signup and view all the answers

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

To prevent catalase aerosols from spreading. Signup and view all the answers

What does the motility test aim to determine?

The ability of an organism to move using flagella Signup and view all the answers

How is the motility test performed?

Stab once into semi-solid media with a straight needle Signup and view all the answers

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

To enhance readability and observation of the reaction. Signup and view all the answers

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

Artificial substrates Signup and view all the answers

Why is the oxidase test used in microbiology?

To identify organisms based on oxidase enzyme activity. Signup and view all the answers

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

Wooden stick Signup and view all the answers