Standard Operating Procedure for Growth Promotion Testing of Antimicrobial Susceptibility Testing Media

1. Purpose

The purpose of this Standard Operating Procedure (SOP) is to provide guidelines for conducting growth promotion testing of antimicrobial susceptibility testing (AST) media. This SOP ensures that the AST media used for bacterial susceptibility testing are of consistent and reliable quality, allowing accurate and reproducible results for antimicrobial sensitivity testing.

2. Scope

This SOP applies to the quality control laboratory or the area responsible for preparing and testing AST media. It includes personnel involved in media preparation, quality control, and laboratory testing.

3. Responsibilities

Laboratory Personnel: Responsible for conducting growth promotion testing following the defined procedure and recording the results accurately.
Quality Control (QC) Supervisor: Responsible for overseeing the growth promotion testing process and ensuring compliance with this SOP.
Laboratory Manager: Responsible for providing resources, equipment, and training required for growth promotion testing.

4. Procedure

4.1 Media Preparation:

Prepare the antimicrobial susceptibility testing media following the manufacturer’s instructions and the approved formulation.
Label the media containers with the appropriate batch number and expiry date.
Store the prepared media as per the storage conditions specified in the manufacturer’s instructions.

4.2 Inoculum Preparation:

Select a well-characterized, quality-controlled microbial strain that is appropriate for the growth promotion testing of the AST media.
Prepare the inoculum

suspension by adjusting the turbidity of the microbial culture to match the recommended standard (e.g., 0.5 McFarland standard).

Inoculate the AST media with the standardized inoculum using aseptic techniques.

4.3 Incubation:

Incubate the inoculated media at the recommended temperature and duration, typically 35-37°C for 18-24 hours.
Use an incubator calibrated for temperature accuracy and stability.

4.4 Growth Promotion Test:

After incubation, visually examine the media for growth.
Positive growth is indicated by visible microbial growth on the media surface.
Negative growth is indicated by the absence of visible microbial growth.

4.5 Interpretation of Results:

If the growth promotion test results are within the acceptance criteria specified in the standard or manufacturer’s instructions, the AST media batch is considered suitable for use.
If the growth promotion test results are outside the acceptance criteria, investigate the cause of failure and take corrective actions, such as retesting, media preparation adjustments, or equipment calibration.

5. Abbreviations

SOP: Standard Operating Procedure
AST: Antimicrobial Susceptibility Testing
QC: Quality Control

6. Documents

The following documents are relevant to this SOP:

AST Media Preparation and Testing Log
Media Preparation and Sterilization Standard Operating Procedure
Microbial Strain Characterization Record

7. References

Refer to the manufacturer’s instructions and relevant standard operating procedures for specific growth promotion testing requirements and guidelines.

8. SOP Version

This is version 1.0 of the SOP for Growth Promotion Testing of Antimicrobial Susceptibility Testing Media, effective as of [Insert Date].