Testing for Gram Positive and Gram Negative Organisms

These flashcards cover the key concepts related to testing for gram positive and gram negative organisms, including the Catalase Test, Coagulase Test, Oxidase Test, and API Test Strip.

What is the purpose of the Catalase Test?

To test for the presence of the enzyme catalase in bacteria.

What is the substrate used in the Catalase Test?

Hydrogen peroxide.

What indicates a positive Catalase Test?

Bubbles forming due to the breakdown of hydrogen peroxide.

Which bacteria is catalase positive?

Staphylococcus sp.

Which bacteria is catalase negative?

Streptococcus sp.

What does the Coagulase Test detect?

The presence of the enzyme coagulase that converts fibrinogen to fibrin.

What is the reagent used in the Coagulase Test?

Rabbit plasma.

What indicates a positive Coagulase Test?

Clotting of the rabbit plasma.

What differentiates Staphylococcus aureus from other Staphylococcus species?

Staphylococcus aureus is coagulase positive.

What is tested in the Oxidase Test?

The presence of the enzyme oxidase in gram negative organisms.

What color indicates a positive Oxidase Test?

Purple.

Name an example of an oxidase positive organism.

Pseudomonas sp.

What is the purpose of the API Test Strip?

To identify enteric gram-negative organisms.

How many tests are included in the API Test?

21 tests.

What do the results of the API Test provide?

A 7-digit number that identifies an organism.