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October 1999


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Steven G Richter <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Mail List <[log in to unmask]>
Thu, 7 Oct 1999 10:36:51 -0400
text/plain (56 lines)
Dear L. Guillardeau

The USP does not specify what to test for Bulk Pharmaceutical product.
However, the bioburden is an important part of your filtration
sterilization process.  The concern with filtration of pharmaceutical
products is the effect of product on cell size.  Organisms that contaminate
water systems are generally oligotrophs that may become even smaller with
product introduction.  Yeasts and Mold cells/spores are generally very
large ( 20-100 micron) and are historically not an issue with terminal
filtration processes.  To answer your question, I would be looking for
small oligotrophic organisms using a non-enriched media such as R2A to
determine the propensity for small organisms getting through a .2 micron
filter.   The yeast and molds counts are important in terms of bulk product
quality but not an large concern in terminal  filtration sterilization

Steve Richter Ph.D.

At 11:56 AM 10/5/99 -0500, you wrote:
>Dear all,
>Do you think that for the bioburden of bulk product before sterilization by
>filtration, we need to perform total microbial count  and  total
>molds/yeasts count or only the total microbial count. USP describe that we
>need to have <10CFU/100ml.
>Thank you in advance for your answers
>Best regards
>The PMFList ( is operated from
>The Microbiology Network ( and supported by
>our sponsors ( as a service to
>the scientific community.
Steven G. Richter Ph.D.
Microtest Laboratories, Inc.
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The PMFList ( is operated from
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