Diluent for the sample tested for the TAMC/TYMC or specified microorganisms:

To check or not to check.

I just looked at our SOPs, and realized, that we don’t check our diluent. We check all the media used in the test for growth promotion qualities and sterility, (every lot is tested for it), but we never check our diluent.
So, if we get it ready - we have a certificate from the manufacturer.
If we prepare the diluent on site - we don’t even have that. Yes, we always use the same recipe …

So, should we check the diluent or not? Can it happen that unchecked diluent has some inhibitive properties? So bacteria (fungi) don’t grow in it?
What are the regulation requirements?

Diluents are normally High purity water and some buffers and they are generally sterile.
Its a valid point to Check a GPT(Growth Promotion Tests) by addind such diluents.

Please look the attached document Page 23 for Diluents to be used as per TGA guideline.

TGA.pdf (181.2 KB)