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Can't find a microbiological vector- any ideas?

microbiology pathogen vector

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#1 bensmith007

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Posted 08 April 2019 - 09:01 PM

Hi all,

 

We recently had a micro hit (Salmonella sp.) as part of our positive release program and we are trying to find the vector but so far failing to do so.

 

We tested all raw material lots and carried out a full environmental swab program of the affected room (drains, walls, floor etc.) but all came back negative (375g samples for the raw materials). The hit came back part way through the cleaning process so swabbing was done post sanitation.

 

Some points:

  • Product is dry blended, contains some vegetable powders, starches, HVP and creamer powder plus salt/ other 'inert' ingredients
  • Most raw materials are received on a COA basis only so are not sampled for micro testing at receiving stage (virtually all treated with some exceptions, all pathogen negative tested by manufacturer)
  • Entire facility is dry blending
  • We have not ever had a positive in the facility (past 3 years)
  • Product was run in several batches over several days, positive came in part way through blending but no obvious candidate from that info (e.g. changing material lot)
  • US based, BRC certified

Next steps- all possibly affected material is on hold, I will recommend to destroy or irradiate all of the product and raw material partials. Other than that, I am unsure where else to go.

 

Are there other things I can be doing here? What is the likelihood of an asymptomatic carrier? We have had no reports of anyone suffering from gastrointestinal issues over the last few months so nothing obvious there. What happens if we can't find a vector? How can I best mitigate any risks from using the same room or equipment for the next production?

 

Your valuable input would be gratefully received...

 

 



#2 Hank Major

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Posted 08 April 2019 - 09:48 PM

Salmonella tests are notorious for false negatives. So even if your initial test detected Salmonella, that doesn't mean that testing the ingredients will find them again. Instead, look through your records for the "dirtiest" ingredient over time, and assume it is the culprit. I would bet it's one of the vegetable powders. Spinach, celery, onion and garlic powders are all filthy.



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#3 Jpainter

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Posted 08 April 2019 - 10:02 PM

Ben, 

 

If I was in your position I would do some increased sampling on the affected lot. In my past job, we used to do n=20 (up to n=60 depending on lot size) testing for pathogen of interest. This should help determine exactly what portion of the run had the pathogen introduced. Of course, this only works if you still have the product on hand, and the product has a production time printed somewhere on the package. If your company does not currently print production time on product, I would recommend it. It is a life saver when it comes to recalls or market withdraws in large production runs for identifying affected product. I too have often wondered about asymptomatic carriers. I think it is a interesting topic, and could be very useful to screen candidates for common food borne illness causing pathogens upon hire and if positives are found having that person work in a low risk area. That would likely break some labor laws, but a cool concept nevertheless. As far as finding a vector, you likely will not. Your adulteration almost certainly occurred from transient pathogens a worked picked up from the environment. I would not worry too much if follow ups were taken and the facility has a good history environmental cleanliness. Risk from shared processing equipment/environment can be mitigated by simply cleaning and sanitizing the area and taken environmental swabs to ensure that the pathogen has not made a home in your facility. If pathogens are found to be an issue on any piece of equipment, I recommend putting a plastic tent around it and pumping full of chlorine dioxide to kill any microorganisms (please be conscious of safety if doing this) .  

Hopefully this helps, 

 

-Jpainter



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#4 Lesley.Roberts

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Posted 09 April 2019 - 09:22 AM

Hi all,

 

We recently had a micro hit (Salmonella sp.) as part of our positive release program and we are trying to find the vector but so far failing to do so.

 

We tested all raw material lots and carried out a full environmental swab program of the affected room (drains, walls, floor etc.) but all came back negative (375g samples for the raw materials). The hit came back part way through the cleaning process so swabbing was done post sanitation.

 

Some points:

  • Product is dry blended, contains some vegetable powders, starches, HVP and creamer powder plus salt/ other 'inert' ingredients
  • Most raw materials are received on a COA basis only so are not sampled for micro testing at receiving stage (virtually all treated with some exceptions, all pathogen negative tested by manufacturer)
  • Entire facility is dry blending
  • We have not ever had a positive in the facility (past 3 years)
  • Product was run in several batches over several days, positive came in part way through blending but no obvious candidate from that info (e.g. changing material lot)
  • US based, BRC certified

Next steps- all possibly affected material is on hold, I will recommend to destroy or irradiate all of the product and raw material partials. Other than that, I am unsure where else to go.

 

Are there other things I can be doing here? What is the likelihood of an asymptomatic carrier? We have had no reports of anyone suffering from gastrointestinal issues over the last few months so nothing obvious there. What happens if we can't find a vector? How can I best mitigate any risks from using the same room or equipment for the next production?

 

Your valuable input would be gratefully received...

 

 

Gosh

 

 This sounds like a big headache for you. I had a similar situation at one of our factories last year, although luckily only one ingredient was implicated so we managed to find the source.

 

Hank’s comments are great & I agree, apart from looking at highest % ingredient in your mix, fruit & vegetables are a risk, especially those from developing countries where agricultural practices may not meet GAP requirements & there is potential for contamination through irrigation water & inadequately treated manure.  Unless your powder producers use a validated heat step during powder production, small amounts of pathogens can be present.  In those instances contamination will not be found throughout a batch but in “pockets”.

 

Your suppliers may have provided you with COAs but unless their loads are homogenous & they have a very robust sampling procedures (eg. milk powder factories where a “trickle sampler” is used to capture 2.5g amounts throughout a batch for screening in 750g) they don’t tell the full story.  As you’ll know this is precisely why HACCP was developed to avoid reliance on end point micro testing.

 

Also you have another issue – if your suppliers have never found pathogens at their production site, either in ingredients or environmental swabs they are likely to question the validity of your results (which was the same issue I had last year) and point to their COAs as ‘proof’ that there were no pathogens present.  I spent months trying to explain the logic of statistical sampling to my senior management team & to the supplier – without much success…. Painful!

 

This also sounds like a very costly experience so I would highly recommend that, as well as serotyping the positive found you also consider Whole Genome Sequencing – not cheap at about $500 per test but this was hugely useful for us because the WGS results provided a clear link to the ingredient, which had been sourced from Asia.  The particular organism found had been linked to that growing region in Asia & thus we were, eventually, able to claim compensation from the supplier.

 

Best of luck!..



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#5 Charles.C

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Posted 09 April 2019 - 10:06 AM

Hi bensmith,

 

Slightly unclear to me as to which sample gave a hit ?? I presume you know which batches of raw material contributed to the sample ? Should be segregated.

 

You may have noticed a recent analogous thread here where the eventual (admitted) conclusion was due to lab error from a contaminated sample. This was after the OP's further analysing ca 100 samples of stored material.

 

As per previous post I would initially make very, very sure that the result is genuine.

 

Having said the above, the chance of (anyone/COA) of detecting Salmonella relates to sampling density, contamination level, and possibly the analytical methodology.  For usual sampling levels and a low percentage of contamination, the statistical chance of locating contaminant is already low. Similar logic for re-checking.


Kind Regards,

 

Charles.C


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#6 wendyleelp

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Posted 16 April 2019 - 11:08 PM

Have you sent all handlers for stool test? It can be transmitted via poor personal hygiene if there is a carrier among you







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