The catalase test is a quick and easy method for the differentiation of Streptococcus and Staphylococcus. All Streptococcus species are catalase negative and Staphylococcus are catalase positive (bubble production) The medium used should NOT have blood incorporated since erythrocytes have catalase activity, which can give false positive results. The test should be done on young cultures 18-24 hours. The reagent used is 3% hydrogen peroxide | Medical Lab Technologist