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May 2001

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Subject:
From:
"Casey, Warren M" <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Mail List <[log in to unmask]>
Date:
Tue, 1 May 2001 09:04:45 -0400
Content-Type:
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Tony,

Your assumptions are correct.  In fact, I think that using cryogenically
stored inocula is the most reproducible method.  The whole issue of
resistance is made more difficult due to the fact that we really don't want
to measure "resistance", we want to measure "sensitivity".  In other words,
the outcome of the test will have a negative impact on the company (failed
batch), but not the patient, if our test strains become resistant to the
preservative in question.  We really need to ensure that our test strains
are not overly SENSITIVE  to the preservative system, a situation that could
have a negative impact on the patient/product.  Since different
preservatives have different mechanisms of action, we would need to develop
a test for maximum resistance AND minimum sensitivity for each organism and
each type of preservative system (i.e., just because an certain organism
meets the criteria for phenol resistance/sensitivity , there is no guarantee
that the same would hold true for resistance to parabens).

I'm a firm believer in the old saying, "If it's not broken, don't fix it".
If there is confusion surrounding the test, it should be cleared up.  But
there is no need (that I am aware of) to modify the test in any substantial
way - especially if it will only add to the confusion.

Warren

> -----Original Message-----
> From: Anthony Cundell [SMTP:[log in to unmask]]
> Sent: Tuesday, May 01, 2001 8:43 AM
> To:   Casey, Warren M; [log in to unmask]
> Subject:      Re: [PMFLIST] Alternate to the Phenol Resistance Test
>
> Warren,
>
> I assume that you agree that the inocula, antimicrobial neutralization and
> culture conditions are critical in terms of the reproducibility of the
> test.  However, I take it you do not support the presence of an internal
> control of a standard preservative/disinfectant that would be run
> periodically as an attempt to standardize the test.
>
> I recommend the book edited by Michael Brown and Peter Gilbert
> "Microbiological Quality Assurance - A Guide Towards Relevance and
> Reproducibility of Inocula. CRC Press 1995 for two excellent chapters on
> the preservative effectiveness test.
>
> Tony Cundell
> Wyeth-Ayerst Pharmaceutical
> >>> "Casey, Warren M" <[log in to unmask]> 05/01 8:05 AM >>>
> Tony,
>
> I believe that culture conditions and test methodology are more realistic
> sources of  apparent "resistance".  We should focus on standardizing these
> aspects of the test rather than opening the Pandora's box of "phenol
> resistance".  The five passage rule was put in place to ensure that
> cultures
> remain genetically and physiologically pure (I'm sure than an extensive
> scientific effort was undertaken to come up with 5, as oppose to 6 or 7
> passages).
>
> Warren
>
> > -----Original Message-----
> > From: Anthony Cundell [SMTP:[log in to unmask]]
> > Sent: Monday, April 30, 2001 4:54 PM
> > To:   [log in to unmask]
> > Subject:      [PMFLIST] Alternate to the Phenol Resistance Test
> >
> > The EPA is actively reviewing the elimination or modification of the
> > Phenol Resistance Test as a requirement for the registration of
> > disinfectants.
> >
> > The purpose of the test is control or verify the resistance of test
> > organisms.
> >
> > The USP attempted to add such as test to the Antimicrobial Effectiveness
> > test as a method of controlling the inherent variability of the test.
> >
> > Does anyone have an opinion as to the direction we should go with this
> > issue?
> >
> > Tony Cundell
> > Wyeth-Ayerst Pharmaceuticals
> >
> >
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>
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