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Media Qualification

Media you can trust the first time.

Every result you report rests on the plate it grew on. Growth promotion testing proves each media lot recovers the organisms it is meant to recover — before that lot ever touches a sample.

USP <61>USP <62>USP <71>
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What growth promotion testing actually proves

A medium can look perfect and still under-recover. Heat damage in autoclaving, a long or warm shipment, a dehydrated base past its date, an inhibitory batch of agar — none of it is visible in the plate. Growth promotion testing challenges the lot with a known, low inoculum of the compendial strains and measures what comes back, so a no-growth result later means no growth, not a medium that could not support it.

How we run it

Each lot is challenged with a calibrated inoculum of not more than 100 CFU of the strains prescribed for that medium, incubated under the conditions the chapter specifies, and read against the acceptance criteria written for the medium type. Solid media are scored on recovery against the calibrated count. Liquid media used for sterility testing are scored on clearly visible growth within the compendial window. Selective media carry the extra burden of proving they still inhibit what they are supposed to inhibit.

  • Solid media: recovery compared against the calibrated inoculum count within a factor of two
  • Sterility media: clearly visible growth within 3 days for bacteria and 5 days for fungi
  • Selective and indicative media: inhibitory and indicative properties confirmed alongside growth
  • An uninoculated portion of every lot incubated as a sterility check before release

What you get back

  • A signed growth promotion certificate for every media lot tested
  • Recovery counts against the calibrated inoculum, scored pass or fail against compendial criteria
  • Strain, passage and media lot traceability for your audit file
  • The sterility check result for the lot
  • Raw data retained and retrievable any time from your Core QC Labs portal
What's included

The scope of growth promotion testing.

Solid media (TSA, SDA, MEA)

Plated media challenged with ≤100 CFU and read against a calibrated inoculum count.

Liquid media (FTM, SCDM)

Sterility media scored on clearly visible growth inside the compendial window.

Selective & indicative media

USP <62> media additionally checked for inhibitory and indicative properties.

Lot sterility check

An uninoculated portion of each lot incubated to confirm the lot itself is clean.

Compendial strains

S. aureus 6538, B. subtilis 6633, P. aeruginosa 9027, C. albicans 10231, A. brasiliensis 16404, C. sporogenes 19404.

Certificate & raw data

A signed GPT certificate per lot with counts, strain traceability and acceptance criteria.

Common questions

Growth Promotion Testing, answered.

Do I still need growth promotion testing if my media came with a certificate?
Most manufacturers ship a certificate of analysis for the lot, and auditors regularly ask for confirmation under your conditions anyway — your incubators, your handling, your storage, after your shipment. The compendial chapters put the burden on whoever uses the medium. Testing on receipt closes that gap and gives you something to point at if a plate later reads unexpectedly.
Which organisms do you challenge the media with?
The panel the chapter prescribes for that medium. Soybean–casein digest media are challenged with Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 10231 and Aspergillus brasiliensis ATCC 16404. Fluid thioglycollate medium adds Clostridium sporogenes ATCC 19404 for the anaerobic challenge. Fungal media are challenged with C. albicans and A. brasiliensis.
How long does growth promotion testing take?
Five to seven business days for solid media, which covers incubation, reading and certificate issue. If your lot also needs the uninoculated sterility check that sterility media require, the full package runs 14 days because that incubation cannot be shortened.
Can you test media I bought from another supplier?
Yes. Growth promotion testing is independent of where the media came from, and testing a third-party lot is one of the more common reasons clients send it to us. Ship the lot with its certificate of analysis and we will test against the criteria for that medium type.
What happens if a lot fails growth promotion?
We tell you before the certificate goes out, not after. A failing lot is re-read and the inoculum verified to rule out a testing artifact, and you get the raw data and the strain records so you can take it up with the supplier. Any samples already read on that lot are flagged so you can decide what needs repeating.
Often run together

Related testing.

Sterility Testing

Membrane filtration or direct inoculation under USP <71>, with the bacteriostasis and fungistasis suitability work that has to come first.

USP <71>

Microbial Limits Testing

Enumeration under USP <61> and tests for specified microorganisms under USP <62> — the pair that releases a non-sterile product.

USP <61>USP <62>USP <1111>

Bioburden Testing

Total aerobic microbial count and total yeast and mold count on raw materials, in-process samples, water and finished units — the number your sterilization cycle is validated against.

USP <61>ISO 11737-1

Ready to scope your growth promotion testing?

Send us the product and the claim you need to support. We'll confirm the method, the sample count and the turnaround before anything ships.

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