Api test microbiology procedure

The API test (Analytical Profile Index) in microbiology , is a biochemical panel-based testing system used to identify microorganisms, primarily bacteria and yeast, by determining their metabolic and enzymatic activities.

API Test Microbiology Procedure steps

Materials Required

• API test strip (e.g., API 20E, API 20NE).
• Distilled water.
• Sterile inoculating loops.
• Sterile test tubes.
• Incubator set to the appropriate temperature.
• Microbial culture (pure isolate).
• API database.

Analytical Profile Index test procedure

• Obtain a pure culture of the microorganism to be tested.Prepare a suspension of the organism in distilled water to match the turbidity equivalent to a 0.5 McFarland standard.
• Open the API strip and place it on a clean, sterile surface.Fill the API strip’s wells with sterile distilled water to create a humid environment.
• Using a sterile pipette or loop, inoculate each well of the API strip with the prepared microbial suspension.
• Place the inoculated strip in the incubation tray.Cover the tray with its lid and incubate at the recommended temperature and duration (e.g., 18-24 hours at 35-37°C).
• After incubation, observe and record the color changes or reactions in each well.
• Enter the results into the API database like manual codebook. Obtain the identification code and determine the organism based on the database.

Note: Always include positive and negative controls when running API tests to ensure accuracy.

Advantage and Disadvantage of Api test microbiology

Advantages

1. Rapid identification compared to traditional methods.
2. Simplified procedure with pre-made panels.
3. Standardized conditions minimize variability.
4. Extensive reference libraries enhance

Disadvantage

1. Api works with isolated, pure cultures of microorganisms.
2. Cannot always identify rare or atypical strains.
3. Api May require additional tests for confirmation of results.