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Streptococcus: catalase test

Differentiating Staphylococcus and Streptococcus is aided biochemically using the catalase test; Staphylococcus are catalase positive and Streptococcus are catalase negative.

After placing a small amount of bacteria on a clean glass slide, the addition of a drop of 3% hydrogen peroxide will produce bubbling in the case of a positive test (bottom of the slide) or no reaction in the case of a negative test (top of the slide). Often the bubbling is not as vigorous as is depicted in this slide.