Oxidase

Sample type

colonies on an agar plate

Uses .

The oxidase test is used to determine if an organism possesses the cytochrome oxidase enzyme.

The test is used as an aid for the differentiation of Neisseria, Moraxella, Campylobacter and Pasteurella species (oxidase positive).

It is also used to differentiate pseudomonads from related species

Interfering factors.

Use of a nichrome or other iron containing loop may yield false-positive reactions. Platinum loops are recommended.

Most Haemophilus are oxidase-positive. Less sensitive strips or reagents may yield false-negative result.

Oxidase reactions of gram-negative bacilli should be determined on non-selective and non-differential media to ensure valid results. Also, colonies taken from media containing high levels of glucose may give false-negative reactions

Precautions:

Do not use wire loop to transfer the culture as oxidase reagent may reacts with iron or nichrome to give false result

Observe the result within 10 seconds as Atmospheric Oxygen may react with reagent to give false positive result.

Culture should not be more than 24 hours old.

Pre analytical errors

Sample preparation

Unlabeled sample

Use of wire loop to transfere the culture.

Post errors

Incorrect results

Delayed report

Corrective action

Don’t use wire loop to transfere culture