Staphylococcus aureus is a gram positive, catalase and coagulase positive coccus and by far the most important pathogen among the staphylococci. It produces enzymes such as catalase which are considered to be virulence determinants.

Why is Staphylococcus catalase positive?

Catalase is an enzyme that converts hydrogen peroxide to water and oxygen gas. The test is easy to perform; bacteria are simply mixed with H 2O 2. If bubbles appear (due to the production of oxygen gas) the bacteria are catalase positive.

Is Staphylococcus catalase negative?

Staphylococcus species are catalase positive and facultatively anaerobic, except for S. aureus subsp. anaerobius and S. saccharolyticus, which are catalase negative and anaerobic.