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Growth promotion test (GPT): Also referred to as fertility or nutritive properties test, which is performed on the media used during different tests like sterility test, microbial limit test, preservative efficacy test to demonstrate that it is capable of supporting the growth of micro-organisms

SOP for Growth Promotion Test (USP)

1.0   PURPOSE:

• • To lay down the procedure for evaluating the growth promotion test and Inhibition property of the sterilized media used for microbiological testing.

2.0   SCOPE:

• • This Standard Operating Procedure is applicable to the Microbiology Department for the Growth Promotion Test and Inhibition property.

3.0   REFERENCES:

• • Guideline for the receipt, storage, preparation, growth promotion test, use and disposal of microbiological media

• • USP – Chapter <62>

• • Guideline – Aseptic Technique for Microbiological Testing.

4.0   PROCEDURE – Growth Promotion Test and Inhibition Test of Media:

• • General Procedure for Growth Promotion Test (GTP) :

• • Growth promotion test shall be performed whenever a new medium is received / Batch No. or lot No. is changed / Make or Vendor is changed.

• • After procuring the Media, check the Media container for the following details i.e. manufacturing date, Expiry date, Code No., and lot. number.

• • Store all the Media in a cool dark place at NMT 25 ± 5°

• • Before taking the media for use, perform the growth promotion (i.e. nutritive properties) or growth inhibition studies specific to the media as per Annexure-4.

• • Whenever there is an approved and “in use” medium available, inoculate it with the same organism.

• • If the growth promotion qualities of the media are not the same as compared to the previously approved lot then discard that media.

• • Procedure to Check the Growth Promotion qualities of the media :

• • Check the growth promotion qualities of the media (Using the organisms as mentioned in Annexure-4) by anyone of the following methods.

• • For newly received agar media

• • containers transfer 1.0 ml of culture having a cell count of 10 to 100 cells in the dilution into two sterile Petri plates and pour the media of New Container [B].

• • Swirl the plates and allow solidifying.

• • Similarly, transfer 1.0 ml of the culture of having a cell count of 10 to 100 cells in the dilution into two sterile Petri plates and pour the prepared Previous Container media [A].

• • Swirl the plates and allow solidifying.

• • Incubate the plates at respective temperatures, after incubation counts the colonies and compare the count with the previous container results.

• • After incubation record the results as per Annexure-2

• • The recovery in the growth promotion test for the new container must be within factor 2 of the actual inoculum concentration obtained for the previous container.

• • For Example: If the standard culture inoculum used has count 100 cfu/ml then the recovery should be within 100/2= 50 cfu/ml and 100*2= 200 cfu/ml.

• • For agar media :

• • Prepare inoculum of known concentration (approximately 10 to 100 cells/ml) of the organism and then transfer it to the plate followed by pouring with the agar media.

• • After incubation record the results as per Annexure-1.

• • For selective agar media :

• • Carryout growth promotion test by streaking specified organisms on the plate and observe for the characteristics of colonies and record the result in Annexure-1.

• • In case of liquid media or broth inoculate 100cfu of inoculum, in 100 ml of media or 10 ml of media by using the organisms as mentioned in Annexure-4 incubate the media,

• • Observe the growth and record the result in Annexure-3.

• • Liquid media are suitable if should show clearly visible growth in media.

• • Put an uninoculated Bottle/Tube/plate of media as a negative control to confirm the sterility of the media.

• • Label or mark using by a marker the name of media, batch/lot no., the organism used tested by, and date on the Bottle/Tube/plate of media.

• • For the growth promotion test of daily prepared media, if more organisms are prescribed for the test, in that case, minimum of two bacteria and one yeast/mold shall be used for tests on a daily rotation basis.

• • For solid media, the recovery of inoculated organisms should not be factor 2 from the calculated value of inoculums added.

Note: Before the use of any batch of prepared media for testing if the growth promotion test is not possible to perform before testing, it can be performed simultaneously with testing.

• • The shelf life of the opened media bottle shall not be more than 12 months and for an unopened bottle, it is till the shelf life of the container.

• • Assign the batch Number :

• • To prepared media with respect to Growth Promotion Test as GPT/MMXXX/YY,

• • Where

• • • GPT stands for Growth Promotion Test

• • • MM stands for Microbiological Media

• • • XXX – 001, 002, 003, ——— to 999

• • • YY    –  Last 2 digits of the calendar year.

• • For example, the first batch number for the year 2020 shall stand as GPT/MM001/20.

• • Growth promotion test shall be performed every finished (Prepared) lots of dehydrated medium.

• General Instructions:

• • All live cultures shall be segregated from areas used for sample testing and optimally,
  • Handle all live cultures in a different area of the laboratory within a Biosafety Cabinet.

• • Positive control dilutions and inoculation shall be performed in a biological safety hood/cabinet

• • Agar plates containing fungal cultures shall be sealed with parafilm to prevent the spread of spores.

• • Surfaces in areas where a was opened shall be sanitized immediately after use by using an approved sanitizer for the appropriate contact time like..

• • • Live culture plate,

• • • Tube,

• • • Bottle,

• • • Pellet, etc.,

• • Gloves shall be used when working with live cultures.

5.0   RESPONSIBILITY:

• • Officer or Executive of the Microbiology Department shall be responsible for the preparation of new or revision of existing SOPs.

• • The Head of the department/designee of respective areas & QA shall be responsible for reviewing the SOPs.

6.0   ABBREVIATIONS USED IN SOP FOR GROWTH PROMOTION TEST:

• • ATCC:   American Type Culture Collection 

• • CC:   Change Control – (SOP for Change Control Management)

• • cfu:   Colony-forming unit

• • EHS:   Environment, Health, and Safety

• • MTCC: Microbial Type Culture Collection

• • NCTC: National Collection of Type Cultures

7.0   ANNEXURES – SOP FOR GROWTH PROMOTION TEST:

Annexure- 1: Media Growth Promotion and Inhibition Test For Agar Media.

Prepare the LOG by using the following table contents-

• • Sr. No.

• • Date

• • Name of Media

• • Media Lot No.

• • Sterilization Cycle No

• • GPT Ref. No.

• • Test for Growth Promoting and Inhibitory Property

• • • Test Organism

• • • Temp. of Incubation

• • • Incubator No.

• • • No. of Cells Inoculated (10-100 cfu)
    • Observation

• • • • Plate I

• • • • Plate II

• • • • Avg.

• • • % Recovery

• • • Test Performed (Pr / In)

• • • Incubation Completed

• • • Recorded by

• • Checked By

Annexure- 2: Newly Received Agar Media-Comparative Test Report.

Annexure- 3: Growth Promotion/ Inhibition Test Record for Liquid Media.

Annexure- 4: Acceptance Criteria for the Growth Promotion Test for Culture Media.

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