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October 1999

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From:
rfriedel <[log in to unmask]>
Reply To:
Robert R. Friedel
Date:
Wed, 20 Oct 1999 17:45:05 -0400
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I commented on this in a previous post back in April.

    [I think most of us will be quite suprised to find out that every
organism found on the Microbial Limit Tests' count plates is
identified by FDA microbiologists (although regulatory bodies tend to always
air on the side of safety and sometimes overkill).       This was discussed
by Dennis Guilfoyle of the FDA Brooklyn facility at the Spring 1999 AAI
seminar.  To those of us utilizing          the pour-plate method for plate
counts, this requirement would be quite cumbersome particularly with
colonies in close                  proximity to one another within the
depths of the agar medium.  I would like to see the procedure as to how one
would choose      one colony over another when it found to be within the
agar.  I can see the utility when the spread plate is utilized but the issue
becomes quite cloudy when it comes to pour plating; not to mention the
presence of product interfering with the                          decision
process.  It is interesting to note that the FDA laboratories utilize
methods which are derived from the Bacteriological      Analytical Manual
(BAM) published by the AOAC (i.e., they use Letheen Broth instead of TSA+LT)
while we are guided/bound      (for the most part) by the methods outlined
in USP]

I try to think in practical terms most of the time.  In a previous
microbiological life, we set up a tier system.  We used a lower
specification and an upper specification.  If the count fell in between the
lower and the upper specification, we would identify the organisms found and
compare them with the specification for that particular dosage form & its
route of administration.  If the organisms of interest to that particular
product were absent, the product passed.  If they were present, the product
failed.  If the product fell below the lower specification, it passed.  If
the product exceeded the upper specification, it failed.  USP indicator
organisms were used in the criteria as well as potential spoilage and
clinically significant organisms.  All the organisms cited as objectionable
had to be recoverable using USP methodology.

We need to better ascertain the relationship between "numerical counts,
organism types and routes of administration" when setting our
specifications.  Even if the organism has been shown to be pathogenic in
certain instances, it still has to be present in a quantity sufficient to
cause infection.  Just because it is there doesn't necessarily mean that
infection will ensue.  We also need to place more emphasis on building
quality into our processes and building an understanding of  microbiology in
terms the "person on the manufacturing line" can understand.  Other
colleagues (chemists, pharmacists, etc..) in the non-microbiological
disciplines would also benefit.  One sure-fire way to get a hands-on view is
to test the microbiota present on their hands using a RODAC plate.  "SEEING
IS BELIEVING".  You can tell someone till you're blue in the face but until
they see a simple example for themselves, change will continue to progress
at a slow pace.

Robert R. Friedel
Quality Assurance Manager
Laboratory Research & Analysis Groups
Perritt Laboratories, Inc.
http://www.perritt.com
[log in to unmask]


----- Original Message -----
From: Lynch, Karen <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, October 20, 1999 4:12 PM
Subject: Re: [PMFLIST] Inhibitory effect of TTC.


> Katherine,
>
> Yes, this is for Total Aerobic Microbial Count, and you're right that it
> would be a big job to subculture every colony if for example there were 40
> colonies detected.  Although we also perform additional tests to test for
> the absence of the USP indicator organisms, colonies detected in TAMC
should
> be identified to some extent to ensure that they are not objectionable
> microorganisms other than the USP indicators.
>
>
> Karen Lynch
> Parke-Davis Research
>
>
> -----Original Message-----
> From: Shih, Katherine [mailto:[log in to unmask]]
> Sent: Friday, October 15, 1999 4:36 PM
> To: [log in to unmask]
> Subject: Re: [PMFLIST] Inhibitory effect of TTC.
>
>
> Karen:
>
> Is this for the Total Aerobic Microbial Count?  If you have recovered,
say,
> 40 colonies, this would be a big job to subculture every colony as we can
> not group them by colony morphology.  For TAMC, do we need to check every
> colony that we have recovered if we also have other tests side-by side for
> the absence of certain objectionable organisms?  Thanks.
>
> Katherine Shih
> Oread
>
> -----Original Message-----
> From: Lynch, Karen [mailto:[log in to unmask]]
> Sent: Friday, October 15, 1999 9:02 AM
> To: [log in to unmask]
> Subject: Re: [PMFLIST] Inhibitory effect of TTC.
>
>
> Laura,
>
> We use 0.5% TTC in our lab to help us differentiate colonies from
particles.
> We run our test with media that does not contain the TTC and at the end of
> the incubation period, we flood the plate with the TTC and allow it to
stand
> for about one hour to allow it to soak into the media and reach the
> subsurface colonies.  We then subculture the colonies immediately and have
> not yet had any problems with recovery.  This method has worked quite
nicely
> for us.  We have no experience with adding the TTC to the media prior to
> pouring the individual plates, so I cannot comment on the inhibitory
effects
> of the TTC when used in that manner.
>
> Karen Lynch
> Parke-Davis Research
>
>
>
>  -----Original Message-----
> From: Laura Acevedo [mailto:[log in to unmask]]
> Sent: Thursday, October 14, 1999 6:33 PM
> To: [log in to unmask]
> Subject: [PMFLIST] Inhibitory effect of TTC.
>
>
>
> Dear colleagues,
>
> I perform microbial limit tests using poured plates . With some products
> (lactose, starch) it is difficult to distinguish the colonies. I know
> there`s the recomedation of using MPN in this cases, but I wonder if it is
> possible to use poured plates adding  TTC to the culture medium to stain
the
> colonies and differentiate them from the product being tested. Has anybody
> validated this method? I`ve heard about possible inhibitory effect of TTC.
> Could someone refer me any paper on this topic?
> Any help would be appreciated, thanks in advance,
>
> Laura Acevedo
> Microbiological Quality Control Manager
> Laboratorio LIBRA
> Montevideo-Uruguay
> [log in to unmask] <mailto:[log in to unmask]>
>
>
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