8 replies to this topic

[miniaczka90]

Hello All .

Quick question, I have been using vidas for listeria testing. And I have been using 25 g. Somebody from work came up with idea to use 125g for testing . But overall I don’t think that would change anything. What are your thoughts?
There is article saying that it doesn’t matter if it is 25 or 125

[tamdongnai]

Hi you

Test in 25 o 125 g: depend on the legal of your country.

Lister in 25 g is different 125 g in a test methold

[Charles.C]

Hello All .

Quick question, I have been using vidas for listeria testing. And I have been using 25 g. Somebody from work came up with idea to use 125g for testing . But overall I don’t think that would change anything. What are your thoughts?
There is article saying that it doesn’t matter if it is 25 or 125

 

The option is noted in Vidas protocol brochure.

 

No experience this methodology but using a larger sample typically increases the chance of including the target pathogen.

 

So does taking more samples.

 

Salmonella sampling is a typical example.

[EagleEye]

Hi miniczka90,

 

 

Definitely it would increase the chance not to miss the pathogen even in a lower count. This would increase the probability to find the organism even if it in the early stages of the entry in to the product.

 

125 g is better than 25 g when sensitivity matters in your test.

[miniaczka90]

Thank you so much !

[moskito]

Hi,

 

this is a question of statistics and requirements. And how to express the results. A single sample is in general based on 25 g

 

125g can mean 5 x 25 g. In both cases the result can experessed as e.g.neg. in 25 g.

 

Micro requirements are often described with  n c n M. Having that you should clearify the reporting.

 

e.g. we report "neg in 25 g" even if the result is based on a sampling of 30 x 25 g (750 g)

From statistics there ist a hugh difference if the test 750 g based on a sampling of 30x25 g or 1x 750 g.

 

Rgds

moskito

[CARIII]

Taking 125 g samples increases the probability of finding pathogens over a single 25 gram sample for very little extra cost.  5-25 g samples gives the same probability of finding pathogens as 1-125 g sample (depending on a few things), but at 1/5 the cost.  So the real question is - Do you want to find something if it is there without spending a lot of money?   If so, larger sample masses are the way to go.  There are lots of stories where pathogens were present, but not detected with 25 g samples.  Some labs are investigating even larger sample masses to increase the probability of detection.  Good luck.

[Charles.C]

Taking 125 g samples increases the probability of finding pathogens over a single 25 gram sample for very little extra cost.  5-25 g samples gives the same probability of finding pathogens as 1-125 g sample (depending on a few things), but at 1/5 the cost.  So the real question is - Do you want to find something if it is there without spending a lot of money?   If so, larger sample masses are the way to go.  There are lots of stories where pathogens were present, but not detected with 25 g samples.  Some labs are investigating even larger sample masses to increase the probability of detection.  Good luck.

 

It is usually preferable to use reference sampling procedures together with validated analytical techniques.

 

For example, as in BAM.

[Tony-C]

Hi miniaczka90,

Have you looked at GUIDELINES ON THE APPLICATION OF GENERAL PRINCIPLES OF FOOD HYGIENE TO THE CONTROL OF LISTERIA MONOCYTOGENES IN FOODS CAC/GL 61 - 2007?
ANNEX II: MICROBIOLOGICAL CRITERIA FOR LISTERIA MONOCYTOGENES IN READY TO-EAT FOODS

 

 CODEX L mono.png   60.63KB   0 downloads

 

5 samples x 25g - Microbiological criteria for ready-to-eat foods in which growth of L. monocytogenes can occur
 
Kind regards,

 

Tony