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Positive Control Check for Pathogen Tests

Qualitative Test Pathogen Test Salmonella E.coli

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#1 BALA Prasanna

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Posted 08 November 2019 - 07:13 AM

Dear Team,

                     We dre doing Qualitative test for Salmonella & E.coli as per BAM Method.

 

We are not compare the result with Positive & Negative Control.

 

Is there mandatory to compare the result with Positive & Negative Control.

 

 

Experts pls clarify

 

 

 



#2 The Food Scientist

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Posted 08 November 2019 - 02:06 PM

You still need to check if your results are valid. So you don't get any false negative or false positive...


Everything in food is science. The only subjective part is when you eat it. - Alton Brown.


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#3 Hank Major

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Posted 08 November 2019 - 08:24 PM

A positive control means you run the test on a sample that you know has Salmonella (or E. coli or whatever). It is checking to make sure that the test can detect them.



#4 BALA Prasanna

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Posted 09 November 2019 - 04:10 AM

ou still need to check if your results are valid. So you don't get any false negative or false positive...

Everything in food is science. The only subjective part is when you eat it. - Alton Brown.

 

 

Dear Madam,

                     We have checked external lab more then 200 results (including PCR). but we didn't get any positive results.

 

If false negative came it was vary in the external lab results.

 

 Is the Positive control is mantatory to test with sample?

 

Because we can justify with ILC results. 


Edited by BALA Prasanna, 09 November 2019 - 04:16 AM.


#5 Charles.C

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Posted 09 November 2019 - 10:11 AM

 

ou still need to check if your results are valid. So you don't get any false negative or false positive...

Everything in food is science. The only subjective part is when you eat it. - Alton Brown.

 

 

Dear Madam,

                     We have checked external lab more then 200 results (including PCR). but we didn't get any positive results.

 

If false negative came it was vary in the external lab results.

 

 Is the Positive control is mantatory to test with sample?

 

Because we can justify with ILC results. 

 

 

Hi Bala Prasanna,

 

^^^^^^

 

also see -

 

https://www.ifsqn.co...is/#entry144567

https://www.ifsqn.co...is/#entry151032

 

 

All this probably comes into the general arena of "Micro. Procedure  Validation".

 

These documents may assist -

 

Attached File  mic1 - Procedure media preparation and growth promotion test.pdf   140.25KB   4 downloads

Attached File  mic2 - Procedure for Validation of Shelf Life of Prepared Micro.Media.pdf   254.11KB   4 downloads

Attached File  mic3 - Procedure for Micro. Media preparation.pdf   115.18KB   2 downloads

Attached File  mic4 - aoac_validation_guidelines_for_food_microbiology.pdf   660.05KB   6 downloads

Attached File  mic5 - micro. method validation US EPA.pdf   1.08MB   7 downloads

Attached File  mic6 - FDA Guidelines Validation methods detection pathogens in foods-Feeds,2015.pdf   1.19MB   7 downloads

Attached File  mic7 - Media growth validation, test methods.pdf   1.84MB   5 downloads

 

Ideally, the lab should probably be doing all these various validation exercises.

In practice it likely depends on what yr iso certification etc demands and what you are actually talking about, eg the latter's safety significance/results etc.

 

For example, IMEX, an unbroken, extended,  history of negative results for something like Salmonella in a raw food is likely a cause for alarm. :smile:


Edited by Charles.C, 09 November 2019 - 10:47 AM.
added

Kind Regards,

 

Charles.C






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