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From:
Rick Jakober <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Date:
Wed, 2 Oct 2019 16:26:41 +0000
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Hi Richard,

Having performed thousands of AET tests over far too many years, I wholeheartedly agree - the test has no real world applications or actual use.....unless it fails. There are far too many microorganisms that can adapt to preserved products to cover all the microbial bases for us to test. The AET test was essentially a way of comparing lab to lab results with some sort of repeatability. A failure indicates that the product is so poorly preserved that it cannot kill off our wimpy, pedigree lab microorganisms and that the very durable and adaptable microorganisms in the real world will (literally) chew up your product if they happen to meet. I always tell my clients, somewhere out there is a bug that will love your product...pray they never meet.
Biofilms are a whole other matter that is only slowly getting interest in determining preservative effectiveness. We have seen and worked on some minor applications in that arena, but I would look into organizations such as the University of Montana’s Center for Biofilm Engineering for more answers. They do seem to be working in Pharma related areas as well as the more common environmental applications.

Rick Jakober
VP Lab Services
Perritt Laboratories, Inc.

> On Oct 2, 2019, at 12:10 PM, Richard Albert <[log in to unmask]> wrote:
> 
> I will take this opportunity to share the following.  The question I have
> always had about USP <51> is how 'real' world it is.  Real world
> microbiology is not a microbe growing in a Petri dish.  I have seen
> formulations containing preservatives be very effective when evaluated
> according to USP <51>.  However the preservatives were not effective when
> the microbial growth was as a biofilm.  Has anyone else observed something
> similar or evaluated preservative effectiveness against microbial growth as
> a biofilm.
> 
> Richard A. Albert
> Senior Microbiologist
> Kleen Test Products
> 
> 
> 
> On Tue, Oct 1, 2019 at 5:04 PM Robert Pritchett <
> [log in to unmask]> wrote:
> 
>> Hello all,
>> 
>> USP <51> AET has the following text regarding preparation of test strains:
>> 
>> "Use standardized suspensions of test strains or prepare as stated below."
>> "The viable microorganisms used in the procedure should be part of a
>> freshly growing culture (e.g., in logarithmic growth phase) with the
>> exception of A. brasiliensis spores."
>> 
>> I've encountered at least one contract lab who uses pre-made commercially
>> available lyophilized cultures specifically marketed for AET. The
>> lyophilized cultures are hydrated and then used for testing and that lab
>> tells me they consider this the mentioned "standardized suspensions" from
>> the USP text. The contract laboratory does perform proper method
>> suitability using the premade AET cultures with passing results and I have
>> seen the validation work for using AET pre-made cultures, but I still
>> question the acceptability of the practice.
>> 
>> My personal opinions/talking points are as follows:
>> - Why? It's simpler and more cost effective to start a fresh culture and
>> any analyst with the title microbiologist should be able to adjust
>> suspensions accordingly
>> - Introducing recently desiccated, starved, frozen, and stressed cells as
>> a challenge to a preservative system seems like a very bad idea - a weak
>> preservative system might pass when it would otherwise fail when challenged
>> with fresh cultures
>> - The validation work cannot possibly represent the varied materials and
>> preservative systems that may be tested for AET
>> 
>> At this time, I've requested laboratories performing AET for my site to
>> always use fresh cultures.
>> 
>> With that said, I'm open to hear what others may say on the topic. Can
>> anybody defend using pre-made commercial cultures for AET?
>> 
>> -RP
>> 
>> 
>> 
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> Science Advisory Board https://www.scienceboard.net/
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> Steris - http://www.sterislifesciences.com/
> 
> Charles River Laboratories - http://www.criver.com/
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> Veltek Associates, Inc - http://www.sterile.com
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> Microbiologics, Inc. - http://www.microbiologics.com
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> BD Industrial Media - http://www.bd.com/ds/
> 
> Boston Analytical http://www.bostonanalytical.com/
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> Associates of Cape Cod, Inc. - http://www.acciusa.com/
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------------------
The PMFList (http://microbiologynetwork.com/pmflist.asp) is operated from
The Microbiology Network (http://microbiologynetwork.com) and 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]



Science Advisory Board https://www.scienceboard.net/

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

Charles River Laboratories - http://www.criver.com/

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

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

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

Boston Analytical http://www.bostonanalytical.com/

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 Microbiology Network, Inc., the PMF, or the sponsors of the list.

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