1. It differentiates between two major bacterial families:
* Oxidase-positive: Bacteria belonging to the family Pseudomonadaceae are oxidase-positive. This means they contain the enzyme cytochrome c oxidase, which is essential for their electron transport chain and energy production.
* Oxidase-negative: Most members of the Enterobacteriaceae family are oxidase-negative. This means they lack cytochrome c oxidase and rely on other enzymes for energy production.
2. API 20E and Enterotube II are specifically designed for identifying Enterobacteriaceae:
* These systems contain biochemical tests that are optimized for identifying bacteria within the Enterobacteriaceae family.
* Performing an oxidase test first eliminates the possibility of working with a non-Enterobacteriaceae bacterium, which would give inaccurate results using API 20E or Enterotube II.
3. Oxidase-positive bacteria may give unreliable results in these systems:
* Some oxidase-positive bacteria may react with certain substrates in the API 20E and Enterotube II systems, producing false-positive results.
* Using these systems on oxidase-positive bacteria would lead to misidentification.
In summary, the oxidase test acts as a preliminary screening tool to ensure the culture is suitable for identification with API 20E and Enterotube II. It helps avoid misidentification and ensures accurate results by focusing on bacteria that are within the scope of these systems.
