Staphylococcus aureus is a gram-positive bacteria known for its ability to produce enzymes, including catalase, which are considered to be virulence determinants.
The catalase test is a simple procedure used to determine the presence of catalase enzyme in bacteria. If bubbles appear (due to the production of oxygen gas), the bacteria are catalase positive.
Staphylococcus aureus is catalase positive and considered to be the most important pathogen among staphylococci. However, some strains of Staphylococcus aureus may be catalase negative, which may lead to a misidentification of the species.
In routine diagnostic laboratories, catalase determination on typical strains is often not performed prior to coagulase testing. Clinicians and microbiologists must be aware of these
atypical strains and infections associated with them to establish their role in pathogenesis. Nevertheless, the catalase test remains an important tool for the differentiation of bacteria, particularly when identifying staphylococci.