The catalase test helps differentiate Staphylococcus from Streptococcus. What result would indicate Staphylococcus?

The catalase test helps differentiate Staphylococcus from Streptococcus. What result would indicate Staphylococcus?

• A. Staphylococcus aureus
• B. Streptococcus pyogenes
• C. Escherichia coli
• D. Pseudomonas aeruginosa

Answer: (A)

The test detects the catalase enzyme. Staphylococcus species produce catalase, which rapidly splits hydrogen peroxide into water and oxygen. When you add a drop of hydrogen peroxide to a Staphylococcus colony, you see immediate bubbling from the released gas. That fizzing indicates a catalase-positive organism, pointing to Staphylococcus. In contrast, Streptococcus lacks catalase, so there would be little to no bubbles. So the result indicating Staphylococcus is the quick, vigorous bubbling after adding hydrogen peroxide.

The test detects the catalase enzyme. Staphylococcus species produce catalase, which rapidly splits hydrogen peroxide into water and oxygen. When you add a drop of hydrogen peroxide to a Staphylococcus colony, you see immediate bubbling from the released gas. That fizzing indicates a catalase-positive organism, pointing to Staphylococcus. In contrast, Streptococcus lacks catalase, so there would be little to no bubbles. So the result indicating Staphylococcus is the quick, vigorous bubbling after adding hydrogen peroxide.