Effective Date: 
Thu, 08/01/2013
Mon, 01/08/2018
Wed, 01/20/2016

Purpose and Scope:

Catalase is the enzyme that breaks hydrogen peroxide (H2O2) into H2O and O2. Hydrogen peroxide is often used as a topical disinfectant in wounds, and the bubbling that is seen is due to the evolution of O2 gas. H2O2 is a potent oxidizing agent that can wreak havoc in a cell; because of this, any cell that uses O2 or can live in the presence of O2must have a way to get rid of the peroxide. One of those ways is to make catalase.
The catalase reaction is used in the identification of gram positive cocci (differentiate between Streptococcus and Staphylococcus species) and some gram positive bacilli.

Reagents and Supplies:

Hydrogen peroxide 3%
Glass microscope slides
Sterile inoculating loops or sticks

Quality Control:

QC is performed on each day the test is performed. Use procedure with stock culture of Staph epidermidis ATCC 12228 (catalase positive) and Strep pyogenes ATCC 19615 (catalase negative).



1. Place a small amount of growth from your culture on to a clean microscope slide. If using colonies from a blood agar plate, be very careful not to scrape up any of the blood agar—blood cells are catalase positive and any contaminating agar could give a false positive.
2. Add a few drops of H2O2 onto the smear. If needed, mix with a toothpick.
(DO NOT use a metal loop or needle with H2O2; it will give a false positive and degrade the metal.)
3. A positive result is the rapid evolution of O2 as evidenced by bubbling.
4. A negative result is no bubbles or only a few scattered bubbles.
5. Dispose of your slide in the biohazard glass disposal container.

Bailey and Scott. Diagnostic Microbiology, 9th ed. St. Louis, Mo., Mosby. 1994.
Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I. Washington DC. ASM Press. 1992.