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Advice on test results (microbiological challenge test)

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#1 Gamewizard



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Posted 27 August 2015 - 02:33 AM

Hi everyone,


I need a bit of advice on the results I have obtained from my experiment.


So I conducted a microbiological challenge test also called PET/AET. 


What i have observed is that there are no log reductions but the bacterial colonies (cfu/ml per plate) have still reduced. The log reductions are like 0.7 or 0.1, or 0.3 which is basically nothing.


Thus i am having hard time analysing results as I do not know whether the preservative system/product in question can be passed off as an effective antimicrobial or not


So how can this be possible ?   has anyone else experienced this too  



#2 Phil Geis

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Posted 28 August 2015 - 03:15 AM

Assume USP <51> or similar protocol.  Not sure why you would expect the result to be otherwise, but +/- 0.5 log is considered normal plate count variability in such tests. It sure doesnlt appear to be effetive.   What is your preservatve system and in what product category?

Edited by Phil Geis, 28 August 2015 - 04:47 AM.

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