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Retesting Samples for Enterobacteriaceae


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#1 downeygirl05

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Posted 13 November 2019 - 04:40 PM

Hello,

 

I've recently sent a sample to a third party lab for testing, Enterobacteriaceae was among the requested testing. The result came back out of spec, our threshold is less than <10CFU. The result was 20CFU. The lab Retested the sample. I've been taught that all pathogenic testing should be confirmed and not rested. Does this also include indicator testing? The sample was also tested for Salmonella and E. coli, which came back negative. Since Enterobacteriaceae is an indicator for both Salmonella and E.coli, I am concerned that the sample was retested and not confirmed. 



#2 kingstudruler1

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Posted 14 November 2019 - 11:55 PM

You are correct in that you cant normally test a product good (retest / test until you get a passing result)

 

What did you want confirmed?  Just that it was actually Enterobacter?   I have never confirmed Enterobacter / coliform results.  If it showed up, I considered it present.



#3 Charles.C

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Posted 15 November 2019 - 07:22 AM

Hello,

 

I've recently sent a sample to a third party lab for testing, Enterobacteriaceae was among the requested testing. The result came back out of spec, our threshold is less than <10CFU. The result was 20CFU. The lab Retested the sample. I've been taught that all pathogenic testing should be confirmed and not rested. Does this also include indicator testing? The sample was also tested for Salmonella and E. coli, which came back negative. Since Enterobacteriaceae is an indicator for both Salmonella and E.coli, I am concerned that the sample was retested and not confirmed. 

 

Hi downeygirl,

 

I'm unsure what you mean by "confirmed". ? There will always be a margin of error of course due sampling/analysis.

 

The lab should be accredited and Procedure(s)  validated.

 

Enterobacteriaceae is IMO not necessarily an indicator for Salmonella/(generic)E.coli.

 

It may depend on the specific situation  but IMEX  one sample/one analysis is insufficient  to make a decisive micro. decision regarding a lot's  compliance with limits.


Kind Regards,

 

Charles.C


#4 MsMars

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Posted 20 November 2019 - 03:44 PM

Did you want the sample confirmed for Entero, or confirmed with pathogenic bacteria species? I've never heard of confirming an indicator species.  Why are you testing for EB if you are already testing for E. coli/Salmonella?

 

Edit: Re-read your post, possibly wanted enumeration of EB, but just qualitative Salmonella/E.coli results (not enumeration).  This is understandable.  I still don't understand the need for confirmation of an enumerative test? The purpose of confirmation is to confirm a pres positive pathogenic bacteria result from a rapid method by utilizing a validated/recognized (but slower) method to confirm that the sample is positive.  Not sure why you would want to do this for an enumeration of an indicator species. 


Edited by MsMars, 20 November 2019 - 04:00 PM.





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