USP Microbial Limits Prep Test

David Lark dlark at
Sat Jan 6 14:32:41 EST 1996

ATG <76235.2473 at CompuServe.COM> wrote:

>Industrial microbiologists: what do you do when Prep Testing for 
>a pharmaceutical product does not validate your ability to 
>recover the test species, despite addition of sorbate, lecithin, 
>attempts at membrane filtration, etc.?  If the product is so 
>inhibitory, does it make sense to run microbial analysis on it in 
>the first place. Or more importantly, can any one predict the 
>Agency's interpretation of this oxymoron (microbial limits on an 
>antimicrobial product/ingredient)?

Their is a classic case here in Australia where a pediatric antibiotic
syrup was heavily contaminated during production with a Kleb.
pneumoniae which had resistance to the particular antibiotic.

Poor plant sanitation and even poorer laboratory recovery techniques
led to the production, distribution and sale of several contaminated
batches and illness, I believe.

Thorough investigation revealed that either beta lactimase inhibition
or gross traditional inactivation was required to recover the
organism. All further testing of this product required test by test
parrallel validation - for every batch.!!!

The conclusion I offer, in answer to your question is:-

Can we as microbiologists ever be sure that we have used every
inhibitor, in every combination at every concentration against every
organism -- only then can we say that the product is "self

Otherwise the little "bug"gers outsmart us in the end.

David Lark

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