Question

Which test is used to differentiate Staphylococcus aureus from other Staphylococcus species?

• A. Catalase Test
• B. Coagulase Test
• C. Oxidase Test
• D. Indole Test

Hint:

{Coagulase-positive Staphylococcus} = \textit{Staphylococcus aureus}.
Most other \textit{Staphylococcus} species are {coagulase-negative}.

Answer 1

The Correct Option is B

Concept: Staphylococcus species are Gram-positive cocci that commonly occur in clusters. To identify and differentiate species within this genus, several biochemical tests are used. The most important distinguishing test is the Coagulase Test, which detects the presence of the enzyme coagulase. This enzyme converts fibrinogen to fibrin, leading to clot formation.
Step 1: Identify the test that differentiates Staphylococcus aureus.

• Catalase Test – Differentiates Staphylococcus (catalase positive) from Streptococcus (catalase negative).
• Coagulase Test – Differentiates Staphylococcus aureus (coagulase positive) from other Staphylococcus species.
• Oxidase Test – Used for identifying certain Gram-negative bacteria.
• Indole Test – Used to detect tryptophan metabolism in bacteria.

Thus, the correct test used to differentiate Staphylococcus aureus is the Coagulase Test.