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November 2019

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Subject:
From:
Donald English <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Date:
Tue, 19 Nov 2019 13:45:21 -0500
Content-Type:
text/plain
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text/plain (229 lines)
Dear Micahel,  

The example that I had given was for validating a pour plate method for a  non-filterable test sample.  For validating membrane filtration method for a test sample, I would add 0.1-ml inoculum containing 10 to 100 CFU to the first rinse fluid of the membrane filter.  By adding the inoculum to a test sample in diluting fluid, I had seen the antimicrobial activity of the diluted 10-ml product aliquot kill the inoculum for some of the test microorganisms because membrane diluting fluids generally do not contain preservative neutralizers.  For a filterable test sample, the methodology is similar in validating a sterility test with the exception that the rinsed membrane filter is placed onto a sterile solid microbial growth agar instead of placement into an enrichment broth.

Regards,
Don

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

Sent from my iPhone

> On Nov 19, 2019, at 11:11 AM, Michael Barton <[log in to unmask]> wrote:
> 
> ´╗┐Hi Don,
> in your worked examples is this just for the pour plate method so that <100 will be in 1ml plated into the petri dish?
> 
> If the product was soluble and tested by membrane filtration and you are testing the entire volume (product and diluent) representing the entire 10g product would you only inoculate <100cfu into the sample or would you inoculate <1000cfu?
> 
> What if you only filtered 10ml of sample (procuct and diluent) representing 1g of sample. What would you inoculate?
> 
> Thanks,
> Mike
> ________________________________
> From: The Pharmaceutical Microbiology Forum Email List <[log in to unmask]> on behalf of Donald English <[log in to unmask]>
> Sent: 14 November 2019 03:07
> To: [log in to unmask] <[log in to unmask]>
> Subject: Re: [PMFLIST] Query on MLT validation
> 
> Dear Nilesh,
> 
> For validating an enrichment test with a 10-gram sample amount into 90 or
> 490 ml of enrichment broth you should always use an inoculum of 10 to 100
> CFU/0.1 ml for each test organism in order to ensure that you are able to
> detect low levels by enrichment .
> 
> To answer your question about using a 1.0 gram or 10-gram test sample to
> validate a plate count method for a 1:10 dilution, a different approach
> needs to be made and the math is as follows for validating with less than
> 100 CFU.:
> 
> 1.0   gram sample amount for each test microorganism:
> 
> 1.0-gram of test sample + 8.9-ml of microbial count diluent + 0.1-ml of
> inoculum with less than 1000 CFU = the final count should be less than 100
> CFU/ml if there are no adverse effects.
> 
> Control:
> 
> 9.9-ml of microbial count diluent + 0.1-ml of inoculum with less than 1000
> CFU   = final count should be less than 100 CFU/ml
> 
> For a 10-gram test sample, everything needs to be multiplied by 10 for each
> test microorganism:
> 
> 10-grams of test sample + 89-ml of microbial count diluent +1.0-ml inoculum
> with less than 10,000 CFU  =   the final count should be less than 100
> CFU/ml if there are no adverse effects
> 
> Control:
> 
> 99.0-ml of microbial count diluent + 1.0-ml of inoculum with less than
> 10,000 CFU   =  the final count should be less than 100 CFU/ml
> 
> A comparison of the 1:10 dilutions for the test sample and control for each
> test organism is made for each test microorganism to validate a plate count
> procedure for a test sample.
> 
> From the math conducted above, it does not matter if a 1.0 or 10-gram test
> sample is used for validating a test sample plate count method because the
> results should be the same.
> 
> As far as incubation, I would always try to incubate the plate count
> plates, enrichment broths and selective/differential media for the minimum
> time periods that are present in USP Chapters 60, 61, and 62..
> 
> Regards,
> 
> Don
> 
> Donald J. English Microbiological Quality Consulting LLC
> 
> Florham Park, New Jersey 07932
> 
> 
>> On Wed, Nov 13, 2019 at 12:52 PM Nilesh Shah <[log in to unmask]> wrote:
>> 
>> Dear Forum members,
>> 
>> Query on Mlt validation.
>> 1.Can I use 1 g sample in 9 ml diluent and after validation can we use 10 g
>> sample in 90 ml diluent during routine testing.
>> 
>> 2.for positive control and product positive control minimum incubation to
>> be followed and for product control maximum incubation to be followed.
>> 
>> 3.culture concentration used for specified organisms should be nmt 100 cfu
>> in total volume.
>> 
>> Thanks
>> Nilesh
>> 9820919185
>> 
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>> 
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>> 
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>> 
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>> 
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>> 
>> =================================
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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.
> 
> ------------------
> 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.

------------------
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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