How does catalase test work

Ensure that you can see the colonies and look at the results immediately. With a sterile swab, touch a plate of Escherichia coli at an area with a large colony or dense growth. Make certain the growth is visible on the swab. If the growth is not visible, it is very difficult to interpret the test results.

Place drops of oxidase reagent onto the visible culture on the swab. If the culture smear turns purple, the organism is oxidase-positive. If the smear remains colorless, the organism is oxidase-negative. University Ave. Visit Campus. Download Viewbook. Give to UW. News Ticker. Contents 1 Principle of Catalase Test 1. Catalase Test: Positive and Negative results.

Catalase Positive and Catalase Negative Reactions. Enterobacteriaceae Gram Positive Cocci. About Acharya Tankeshwar Articles. Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. I am working as an Asst. Culture should be 18 to 24 hours old.

Hydrogen peroxide must be fresh as it is very unstable. Iron wire loop should not be used. Some bacteria produce a peroxidase that catalyzes a breakdown of hydrogen peroxide causing the reaction to be weakly positive; a few bubbles elaborated slowly. This should not be confused with a truly positive reaction. Do not add organism to reagent, particularly if iron-containing inoculating loops are used.

Iron containing loops will cause false positive test results if exposed to hydrogen peroxide. Yes candida and aspergillus are catalase positive Reply.

Ankur Reply. Did you ever get an answer to this? I found the same curious result. Please advise. At what temperatures does this experiment requires because here in Kenya it is very cold Reply. Hi, I am finding very difficult to differentiate Rhodococcus sp, from Roseomonas and Methylo bacterium.