SOP Title: Testing Growth Promotion, Inhibitory and Indicative Properties of Culture Media
- Objective:
To lay down the procedure for Testing Growth Promotion, Inhibitory and Indicative Properties of Culture Media.
- Scope
This procedure is applicable for Testing Growth Promotion, Inhibitory and Indicative Properties of Culture Media in the Microbiology Section of Quality Control Department.
- Responsibility:
- Quality Control Department: To prepare and review the SOP. To follow the procedures for Testing Growth Promotion, Inhibitory and Indicative Properties of Culture Media as per this SOP.
- Quality Assurance Department: To review and approve the SOP and Annexure.
- Accountability:
Head Quality Control Department, Head Quality Assurance Department.
- Procedure:
| 5.1 | Safety Precautions/Instructions: | |
| 5.1.1 | Always wear protective nose masks and gloves while carrying out the microbiological activities. | |
| 5.1.2 | Use spatula which is clean, preferably wiped with 70% v/v Isopropyl alcohol and dried, for weighing of each media. | |
| 5.2 | Procedure for Testing: | |
| 5.2.1 | Growth Promotion, Indicative and Inhibitory Properties of each lot of dehydrated media container shall be carried out before its usage and after every six months until its consumption or expiry, as applicable. | |
| 5.2.2 | On receipt of Culture Media, make the entry in respective format of SOP, ‘Procedure for Receipt and Storage of Dehydrated Culture Media used for Microbiological Analysis’. | |
| 5.2.3 | For testing, prepare the required quantity of Culture Media based on the number of organisms used for the test and sterilise as per Procedure for Media Preparation SOP. Refer annexure for Media name, media tests (Growth promotion, Inhibitory, Indicative tests) and test culture to be used with incubation temperature and time. | |
| 5.2.4 | Allow the media to cool at 40-45°C after sterilization. | |
| 5.2.5 | In case of Agar medium pour the media in plates and let them solidify. | |
| 5.2.6 | Carry out the analysis under Laminar Air Flow unit. Refer SOP ‘Procedure for Operation of Laminar Air Flow bench’. | |
| 5.2.7 | Remove the specified culture dilution for a given media by referring annexure of not more than 100 CFU from the refrigerator. Refer SOP ‘Procedure for Serial Dilution Preparation of Microbial Cultures.’ | |
| 5.2.8 | Allow the culture dilutions to attain room temperature. | |
| 5.3 | Test for Growth Promoting Properties of Solid Media: | |
| 5.3.1 | In case of solid media perform the surface spread method using spreader. | |
| 5.3.2 | Pipette and spread on the surface of the agar plate with 0.1 ml of known number of microorganisms ( approximately NMT 100 CFU). | |
| 5.3.3 | Incubate for not more than the specified shortest period of time and temperature till a clear visible growth is obtained. Record the details and observations in Annexure. | |
| 5.3.4 | Media under test should be considered suitable if growth obtained is comparable to that obtained on the same medium, previously tested and approved. | |
| 5.3.5 | Growth obtained on solid media must not differ from the calculated CFU of the standardized inoculum by a factor greater than 2 or should be comparable to that obtained on the same medium previously tested and approved. i.e. recovery should be within 50% to 200%. Refer Annexure. | |
| 5.4 | Test for Growth Promoting Properties of Liquid Media: | |
| 5.4.1 | Inoculate 10 ml of the medium with 0.1 ml of required culture using pipette. | |
| 5.4.2 | Incubate for not more than the specified shortest period of time and temperature till a clear visible growth is obtained. Record the results in annexure. | |
| 5.4.3 | The liquid media shall be observed for turbidity to confirm the growth of microorganism. If no turbidity is observed then it is considered as no growth. | |
| 5.5 | Tests for Inhibitory Properties of Liquid/Solid Media | |
| 5.5.1 | Inoculate each plate in case of solid media or tube in case of liquid media with 0.1 ml of required culture and incubate at the specified temperature for the time specified in the test. Refer Annexure. | |
| 5.5.2 | There should not be any growth of the micro organisms on this medium. | |
| 5.6 | Tests for Indicative Properties of Liquid/Solid Media: | |
| 5.6.1 | Perform the surface spread method, in-case of solid media inoculating each plate with 0.1 ml of required culture and spreading; in case of liquid media directly inoculate 0.1 ml of required culture in the media. | |
| 5.6.2 | Enter the records in Annexure. | |
| 5.6.3 | Incubate at the specified temperature for the time specified in the test Refer Annexure. | |
| 5.6.4 | Colony morphology and Biochemical indication reaction should be similar to that obtained with the previously approved batch of the medium. | |
| 5.6.5 | Perform a negative control for specified time and temperature as per the test, wherein no growth of microorganisms should occur. | |
| 5.6.6 | Refer Annexure for Growth Promotion Record. | |
| 5.6.7 | Growth of the micro organisms must be comparable to that obtained with previously tested and approved batch of medium. | |
| 5.6.8 | If the media passes the Growth Promotion Test (GPT), an approved label shall be affixed on the all the media containers as per Annexure and the same should be used for routine analysis.
Note: – If Multiple containers of same batch numbers are received at one time, then the Growth promotion test of every container not necessary to perform. If same batch number container are received on two different days then perform GPT separately. |
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| 5.6.9 | If the media fails for the Growth Promotion Test, discard the media and prepare fresh media again to repeat the test. Incident report should be filled in case on non-compliance of the test. | |
| 5.6.10 | After completion of growth promotion test, all the used media and glasswares should be decontaminated as per SOP “Destruction of Cultures and Microbial waste. | |
- Definitions / Abbreviation:
- Definitions:
- Abbreviation:
| Abbreviation | Expansion |
| °C | Degree Centigrade |
| CFU | Colony Forming Unit |
| ml | millilitre |
| LAF | Laminar Air Flow |
| % | percent |
*Note – Ready to use SOP available in “DOWNLOAD” Section.