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From:
Marc Glogovsky <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Date:
Wed, 17 Jun 2020 11:38:36 -0400
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Personally, I wouldn’t see a need for pre-wetting, given the article being tested in this example.  Water should have no compatibility issues with your filter and given the fact that you would be testing a minimum of 100mL of water, you would be fine to test as is (no rinsing).

To answer Don's question, 0.22um filters are designed for bacterial RETENTION (i.e. sterile filtration, etc.), while 0.45um filters are designed for bacterial RECOVERY.

This debate is an old one, however, diffusion of nutrients from the agar plate are inhibited by a 0.22um filter due to pore size.  0.45um gives the best recovery of microorganisms due to improved growth conditions on the surface of the membrane.  Many studies show this (I know Millipore has performed dozens, if not more over the decades).  Given the organisms we routinely recover in water systems and filterable bioburden samples, you would not expect any organism loss due to the larger pore size of the 0.45um.  You can always demonstrate this in a lab study should there be any doubt.

Sincerely,
 
Marc Glogovsky, MS, S.M. (NRCM)
Senior Consultant - Microbiology
 
918A Horseshoe Pike, Downingtown, PA 19335
P: 610.269.2808 | F: 610.269.4069
M: 609.432.1314 | valsource.com <http://valsource.com>

On 6/17/20, 8:42 AM, "The Pharmaceutical Microbiology Forum Email List on behalf of Donald English" <[log in to unmask] on behalf of [log in to unmask]> wrote:

    Hi Tim,

    It is my understanding that membrane filter composed of mixed cellulose fibers have a quick wetting time in which a pre-wetting might not have to be performed.  Is this correct?

    What is your  opinion in about using hydrophilic membrane filters that are composed of PTTE or Nylon if there is a concern about binding of ingredients in an aqueous formulation to the filter?  From conducting preservative challenge testing, I do know that Methylcellulose is able to bond to certain types of preservatives.  If there was an issue, I think that this would come up in the performance of suitability testing of the formulation in which spiked microorganisms could not be recovered.

    For conducting membrane filtration of purified water samples, I see no reason as to why a membrane filter composed of mixed cellulose fibers cannot be used on a routine basis without pre-wetting since a normal aliquot for testing is 100-mls.

    The next question then comes up as whether it is best to use a 0.22 or 0.45 micron membrane filter for water testing.  I have seen many opinions expressed during the years in which one is the best for usage.

    Regards,
    Don

    Donald J. English Microbiological Quality Consulting LLC
    Florham Park, New Jersey 07932


    Sent from my iPhone

    > On Jun 16, 2020, at 4:31 PM, Crystal Booth <[log in to unmask]> wrote:
    > 
    > Hi Alison,
    > 
    > I agree with Tim. Also, if you are testing a small amount, you can add it to a sterile diluent (such as sterile water or Fluid A, etc.) prior to filtering the entire amount.  You'd want to do a negative control of your diluent.
    > 
    > Kind regards,
    > Crystal Booth
    > 
    > Crystal Booth, M.M.
    > Regional Manager
    > PDASE Chapter President
    > PSC Biotech Corporation
    > 700 Corporate Center Drive Pomona, CA 91768
    > Mobile (909) 620-0757
    > https://www.biotech.com/
    > 
    > 
    > 
    > -----Original Message-----
    > From: The Pharmaceutical Microbiology Forum Email List <[log in to unmask]> On Behalf Of Timothy Cser
    > Sent: Tuesday, June 16, 2020 12:24 PM
    > To: [log in to unmask]
    > Subject: Re: [PMFLIST] Water Filtration Bioburden
    > 
    > [CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.]
    > 
    > Hi Alison.  How much water are you testing?  If it’s 100mL a pre-wet isn’t needed.  If it’s a small amount like 5mL, you can pre-wet with 10-20mL of sterile water/diluent.  Pre-wetting is designed to minimize any binding of the article you’re wishing to test but water isn’t a problem.
    > 
    > Tim Cser
    > MilliporeSigma
    > MilliporeSigma is a division of Merck KGaA, Darmstadt, Germany
    > 
    >> On Jun 16, 2020, at 9:18 AM, Berman, Alison <[log in to unmask]> wrote:
    >> 
    >> Hi all,
    >> For those of you performing bioburden testing of waters using the filtration method, are you using a pre-wet, a rinse, or both a pre-wet and a rinse?
    >> If a study is performed showing equivalency with and without a pre-wet and/or rinse, it is acceptable to forego them?
    >> Thanks
    >> 
    >> Alison Berman, MFS
    >> Supervisor
    >> Quality Control - Microbiology
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    > 
    > 
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    > Charles River Laboratories - https://www2.criver.com/l/60962/2020-03-27/h6jqv6
    > 
    > Veltek Associates, Inc - http://www.sterile.com
    > 
    > Microbiologics, Inc. - http://www.microbiologics.com
    > 
    > BD Industrial Media - http://www.bd.com/ds/
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    > Associates of Cape Cod, Inc. - http://www.acciusa.com/
    > 
    > 
    > =================================
    > The nature of this service is to provide a medium for communication.  The specific statements and endorsements of individuals participating in the discussions are not necessarily those of the PMF or the sponsors of the list.

    ------------------
    The PMFList is supported by our sponsors as a service to the scientific community.

    Please take a second to visit our sponsors' web sites and say thank you for their support of this service.
    If your company would be interested in sponsoring this community, please contact [log in to unmask]



    Steris - http://www.sterislifesciences.com/

    Charles River Laboratories - https://www2.criver.com/l/60962/2020-03-27/h6jqv6

    Veltek Associates, Inc - http://www.sterile.com

    Microbiologics, Inc. - http://www.microbiologics.com

    BD Industrial Media - http://www.bd.com/ds/

    Associates of Cape Cod, Inc. - http://www.acciusa.com/


    =================================
    The nature of this service is to provide a medium for communication.  The specific statements and endorsements of individuals participating in the discussions are not necessarily those of the PMF or the sponsors of the list.

------------------
The PMFList is supported by our sponsors as a service to the scientific community.

Please take a second to visit our sponsors' web sites and say thank you for their support of this service.
If your company would be interested in sponsoring this community, please contact [log in to unmask]



Steris - http://www.sterislifesciences.com/

Charles River Laboratories - https://www2.criver.com/l/60962/2020-03-27/h6jqv6

Veltek Associates, Inc - http://www.sterile.com

Microbiologics, Inc. - http://www.microbiologics.com

BD Industrial Media - http://www.bd.com/ds/

Associates of Cape Cod, Inc. - http://www.acciusa.com/


=================================
The nature of this service is to provide a medium for communication.  The specific statements and endorsements of individuals participating in the discussions are not necessarily those of the PMF or the sponsors of the list.

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