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From:
Don English <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Date:
Wed, 14 Oct 2009 11:05:40 -0400
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Dear Wendie,

      With the use of mixed inoculum, it has to be understood that
biochemical identification of recovered microorganisms from the plate
counts will need to be performed to determine why a preservative is not
working against a certain organism.  There are alot of arguments for and
against using a mixed or a single pure culture inoculums in challenge
testing.  The biggest advantage of using a single, pure culture inoculum is
that it is definitely easier to determine what organism is having a problem
in the challenge test.  By using mixed inoculum pools, the advantage is
that more different types of organisms can be used to evaluate the
effectiveness of  a preservative system in a product formulation than the
standard 5 types of organisms that are used in the USP Antimicrobial
Effectiveness Test.  However, there have been arguments saying that a
single, pure culture inoculum is not realistic because it does not
represent the real-world because microorganisms exist in mixed communities
that consists of different strains.  I have seen people make the argument
for and against  using a mixed inoculum because it places a more severe
stress on the preservative system than the use of a single, pure culture
inoculum and will allow for most the dominant or most opportunistic species
to be revealed if the preservative system or the concentration of a
preservative is inadequate.  However, it should be noted  that if you are
using a mixed inoculum that you should be dividing the organisms into
inoculum pools that share  a common characteristic(Gram-stain, biochemical
reactions, morphology, etc.) between the test organisms because some
organisms are able to inhibit the growth of each other in a product
formulation by the competition for microbial nutrients and growth factors
such as iron.
      It is my opinion that not enough research has been performed to say
which type of inoculum (single vs,. mixed culture) should be used for
performing challenge testing.  In the end, it is a company decision to use
a mixed or single culture inoculums for challenge testing.

Don



                                                                           
             "Hutchings,                                                   
             Wendie"                                                       
             <Wendie.Hutchings                                          To 
             @NORWICHPHARMA.CO         [log in to unmask]         
             M>                                                         cc 
             Sent by: The                                                  
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             Microbiology              Re: [PMFLIST] Preservative Efficacy 
             Forum Email List          Testing                             
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             CROBIOL.ORG>                                                  
                                                                           
                                                                           
             10/14/2009 09:49                                              
             AM                                                            
                                                                           
                                                                           
             Please respond to                                             
                    The                                                    
              Pharmaceutical                                               
               Microbiology                                                
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If PET are pooled how does one determine which bug is which without
time-consuming--often expensive--identification? For the T-0 counts, how
does one assert unequivocally microorganism growth is just the intended
inocula not ineffective preservative? A niger versus E. coli should be a
no-brainer but...

Wendie S. Hutchings
Microbiology Laboratory Analyst
Norwich Pharmaceuticals, Inc
6826 State Highway 12
Norwich, NY 13815
Phone (607) 335-3064
Fax: (607) 335-3001



-----Original Message-----
From: The Pharmaceutical Microbiology Forum Email List
[mailto:[log in to unmask]] On Behalf Of Geis, Phil
Sent: Wednesday, October 14, 2009 7:29 AM
To: [log in to unmask]
Subject: Re: [PMFLIST] Preservative Efficacy Testing

Think pools are commonly used and you'd be advised to understand
dynamics within pool (esp. antagonism between bugs).

Suggest PET at each of these stages.

-----Original Message-----
From: The Pharmaceutical Microbiology Forum Email List
[mailto:[log in to unmask]] On Behalf Of Jermyn, Bob
Sent: Wednesday, October 14, 2009 5:57 AM
To: [log in to unmask]
Subject: [PMFLIST] Preservative Efficacy Testing

Dear Colleagues,



Does anyone conduct the following PET tests with a pooled group of
micro-organisms instead of an individual test for each micro-organism?



At what stage of cosmetic product development/manufacture is best to
conduct the PET - on lab batches, miniature pilot batches, or full-scale
manufactured batches?



Thanks,



Bob


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The Microbiology Network (http://microbiol.org) and supported by
our sponsors (http://microbiol.org/sponsor.htm) 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.

Accugenix - http://www.accugenix.com

American Type Culture Collection - http://www.atcc.org

Applied Biosystems, MicroSeq Microbial ID System -
http://www.microseq.com/

BD Diagnostic Systems - http://www.bd.com/ds/

Biolog - http://www.biolog.com

Biomerieux - http://industry.biomerieux-usa.com

EMD Chemicals - http://www.emdchemicals.com

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

Millipore - http://www.millipore.com

MODA Technology Partners - http://www.modatp.com

Pall - http://www.pall.com

NovaTek International - http://www.ntint.com

Rapid Micro Biosystems - http://www.rapidmicrobio.com  (formerly GPS)

Raven Biological Labs - http://www.ravenlabs.com

Veltek Associates, Inc - http://www.sterile.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 Microbiology Network,
Inc., the PMF, or the sponsors of the list.

------------------
The PMFList (http://microbiol.org/PMFList_info.htm) is operated from
The Microbiology Network (http://microbiol.org) and supported by
our sponsors (http://microbiol.org/sponsor.htm) 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.

Accugenix - http://www.accugenix.com

American Type Culture Collection - http://www.atcc.org

Applied Biosystems, MicroSeq Microbial ID System - http://www.microseq.com/

BD Diagnostic Systems - http://www.bd.com/ds/

Biolog - http://www.biolog.com

Biomerieux - http://industry.biomerieux-usa.com

EMD Chemicals - http://www.emdchemicals.com

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

Millipore - http://www.millipore.com

MODA Technology Partners - http://www.modatp.com

Pall - http://www.pall.com

NovaTek International - http://www.ntint.com

Rapid Micro Biosystems - http://www.rapidmicrobio.com  (formerly GPS)

Raven Biological Labs - http://www.ravenlabs.com

Veltek Associates, Inc - http://www.sterile.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 Microbiology Network, Inc.,
the PMF, or the sponsors of the list.

------------------
The PMFList (http://microbiol.org/PMFList_info.htm) is operated from
The Microbiology Network (http://microbiol.org) and supported by
our sponsors (http://microbiol.org/sponsor.htm) 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.

Accugenix - http://www.accugenix.com

American Type Culture Collection - http://www.atcc.org

Applied Biosystems, MicroSeq Microbial ID System - http://www.microseq.com/

BD Diagnostic Systems - http://www.bd.com/ds/

Biolog - http://www.biolog.com

Biomerieux - http://industry.biomerieux-usa.com

EMD Chemicals - http://www.emdchemicals.com

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

Millipore - http://www.millipore.com

MODA Technology Partners - http://www.modatp.com

Pall - http://www.pall.com

NovaTek International - http://www.ntint.com

Rapid Micro Biosystems - http://www.rapidmicrobio.com  (formerly GPS)

Raven Biological Labs - http://www.ravenlabs.com

Veltek Associates, Inc - http://www.sterile.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 Microbiology Network, Inc., the PMF, or the sponsors of the list.

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