Path Lab - Microbiology 2 Flashcards Preview

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Flashcards in Path Lab - Microbiology 2 Deck (5):
1

How can you tell the difference between Staph aureus and other Staph species?

S aureus is coagulase positive
Other staph are coagulase negative staph

2

How can you tell the difference between Strep and Staph?

Using the Catalase test
Staph is catalase positive and causes oxygen bubbles

3

Which two broad groups of bacteria are differentiated by the oxidase test?

Enterobacteriaceae, and other gram negative rods.
This test is often used to distinguish between Enterobacteriaceae and Pseudomonas aeruginosa

4

How is a coagulase test performed?

Slide coagulase test: this is the rapid but less reliable form of the test. A portion of a staphylococccal colony is emulsified in a drop of plasma on a glass slide using a wooden toothpick, producing a milky suspension. If coagulase is present, the bacteria and fibrin will clump together within minutes, giving the suspension a granular appearance. The suspension remains homogenous if coagulase is not present.

Vs Tube Coagulase Test

5

How does the oxidase test work?

The test detects the presence of CYTOCHROME OXIDASE, an enzyme in the electron transport chain of some bacteria but not others. In the test, a colourless compound takes the place of oxygen in the real chemical reaction, and when this is reduced it becomes blue.

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