Supplements and additives
Oxidase Reagent
Reagent for the detection and verification of bacterial cytochrome oxidase.
- Cat. No.
- LC-6007
- Category
- Supplements and additives
- Format
- 2 x 25 swabs
- Storage
- 2 to 14 °C
- Minimum guaranteed shelf life
- 6 months
The basis of the test is the following: cytochromes are hemoproteins that act as oxidant enzymes in the transport chains of oxidative phosphorylation electrons. Generally, cytochromes are found just in the aerobic bacteria, whereas the strict anaerobes do not present them. Cytochrome oxidase found even in the Enterobacteriaceae is composed of a3-cytochrome. However, the substance that the Oxidase Reagent is able to reduce is c-cytochrome, thus the test just determines the presence of c-cytochrome and therefore the test is positive only for the bacteria that have c-cytochrome in their respiratory chains.
Key features
Presentation
2 metallic bags of 25 swabs.
Description and technique
Technique
Soak a swab with the isolated colony which is going to be classified, after 24 hours of incubation in TSA or Nutrient Agar.
The reading must be done after 20-30 seconds. The bacterium is oxidase positive if the swab shows a red - dark red - purple colour.
When the reaction in the colony is very slow, it has to be considered negative or very weak, since the late appearance of colour is more attributable to the spontaneous oxidation than to the true presence of c-cytochrome.
Note: it is recommended to close the bag with the rest of the swabs as soon as possible, to protect them from light and oxidation.
Presentation
| Presentation | 2 metallic bags, 25 swabs/pack |
|---|---|
| Filling | N/A |
| Packaging | 2 self-closing metal bags containing 25 swabs impregnated with oxidase reagent. |
Composition
| Ingredient | Amount per swab |
|---|---|
| N,N-dimethyl-p-phenylenediamine | 10 mg |
Technique
Isolate on TSA or Nutrient Agar, then identify the pure culture. Soak the swab with a colony.
Oxidase +: colony turns red-garnet.
Oxidase -: colony colourless to slightly pink.
Note: close the bag with the rest of the swabs as soon as possible, to protect them from light and oxidation.
Quality control
Physical/chemical control
| Color | Colourless |
|---|
Microbiological control
Impregnate the swab with a recently isolated pure culture.
Observe the colour turn of the colony after 20-30 seconds.
| Microorganism | Growth |
|---|---|
| Escherichia coliATCC 25922, WDCM 00013 | Oxidase negative - white to pink |
| Ps. aeruginosaATCC 9027, WDCM 00026 | Oxidase positive - garnet |
| Ps. aeruginosaATCC 27853, WDCM 00025 | Oxidase positive - garnet |
Sterility control
Not applicable.
Bibliography
- BLAZEVIC, D.J., G.M. EDERER (1975) Principles of Biochemical Test in Diagnostic Microbiology. John Wiley Sons. NY.
- FORBES, B.A., D.F. SAHM, A.S. WEISSFELD (1998) Bailey & Scott's Diagnostic Microbiology. 10th ed. Mosby. St. Louis.
- GABY W.L., C. MARTLEY (1957) Practical laboratory test for the identification of Pseudomonas aeruginosa. J. Bact. 74(3):356-358.
- GORDON, J. & J.W. McLEOD (1928) The practical application of the direct oxidase reaction in bacteriology. J. Pathol. Bacteriol 31(2):185-190.
- HARRIGAN, W.F. & M.E. McCANCE (1976) Laboratory Methods in Food and Dairy Microbiology. Academic Press. London.
- McFADDIN, J.F. (1999) Biochemical Tests for Identification of Medical Bacteria. 3rd ed. Lippincott Williams & Wilkins. Philadelphia. USA.
- STEEL, K.J. (1962) The oxidase activity of staphylococci. J. Appl. Bacteriol. 25(3):297-306.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
Every lot comes with its certificate.
Tracked shipment
Follow your shipment live, from our warehouse to your lab.
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Frequently asked questions
Can I ask for formats other than those listed?
Yes: custom formats and OEM packs are available on request. Tell us the quantities you need.
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