Question

Which of the following is true about the catalase test when used to differentiate between streptococci and staphylococci?

• A. Streptococci are catalase-positive, and staphylococci are catalase-negative.
• B. Staphylococci are catalase-positive, and streptococci are catalase-negative.
• C. Both staphylococci and streptococci are catalase-positive.
• D. Both staphylococci and streptococci are catalase-negative.

Hint:

Remember the classic diagnostic differentiation rule:
- Staphylococcus = Catalase-Positive (bubbles form)
- Streptococcus = Catalase-Negative (no bubbles)

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The catalase test detects the presence of the enzyme catalase, which breaks down toxic hydrogen peroxide (\(\text{H}_2\text{O}_2\)) into water and oxygen gas.

Step 2: Detailed Explanation:
- The catalase test is a fundamental microbiological assay used to differentiate between major groups of Gram-positive cocci:
- Staphylococci (Staphylococcus species) possess the catalase enzyme and are catalase-positive (producing immediate bubbling/effervescence when hydrogen peroxide is added).
- Streptococci (Streptococcus species) lack this enzyme and are catalase-negative (producing no bubbles).

Step 3: Final Answer
Staphylococci are catalase-positive, whereas streptococci are catalase-negative.