Catalase

Uses:

1) The morphologically similar Enterococcusor Streptococcus (catalase negative) and Staphylococcus (catalase positive) can be differentiated using the catalase test.

2) Also valuable in differentiating aerobic and obligate anaerobic bacteria.

3) Semiquantitative catalase test is used for the identification of Mycobacterium tuberculosis.

4) Sample type:Colonies from blood agar.

Precautions :

1) The test organisms should not be taken from blood agar culture. Red Blood cells contain catalase and their presence will give a false positive test.

2) Culture should be 18 to 24 hours old.

3) Hydrogen peroxide must be fresh as it is very unstable.

4) Iron wire loop should not be used.

5) 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.

6) Interfering factors:

The test organisms should not be taken from blood agar culture. Red Blood cells contain catalase and their presence will give a false positive test. 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.

Corrective action:

You must sterile the loop

Reject unlabeled sample.

Not take organisms from blood agar culture.

Pre analytical errors:

Sample collection

Unlabeled sample

Non sterilized loop .

Post errors:

Delayed report

Sent results to incorrect patient .