Listeria

Hi all

My samples for raw fish are returning positive for Listeria monocytgenes and L.grayi and L.innoua sometimes too ....test is a simple presence not a numeration one ,so do not have the numbers present........................what i want to know is that considering this is a raw product and listeria is (as far as i know) killed by conventional methods should I be worried ?

Have asked fellow Q professionals ,govt bodies and searced the web and cannot get a simple answer!!!!!

Any info greatly received


valb

Dear Val,

Sorry delay in answering. I can advise on this one although you may have already got an answer from the textbooks ?
The fact is that very frequently in the seafood world L.mono… is classified as an ubiquitous environmental contaminant. Its relatively recent detection caused an initial zero tolerance in nearly everything however this proved unsustainable for documented reasons so that its presence in raw seafoods is frequently considered inevitable although the precise levels of acceptability are still debated. For RTE products if you want more precise info wud suggest you look at some of the mic.guidelines already x- referenced this forum or revert and I (or anybody else) can advise further.

Rgds / Charles.C

Hi charles

Thank you for the most comprehensive answer I have recieved to date.

The only micro guideline I sourced ,is for RTE being

Dear Val,

I think you are correct in that it is not easy to find definitive statements of official requirements for L.mono in raw seafoods. This is probably in part due to the fact that there was a very adverse general initial response which then became somewhat of an embarrassment when the 'natural'ubiquity became evident in many commercially traded seafoods together with detailed quantitative studies on the significance of L.mono. in RTE items.
As a result many countries 'decontrolled' L.mono from the tested pathogens in raw seafoods destined to be cooked before consumption.

The situation for some RTE items (but not all) is illustrated in these forums in the micro.criteria thread, eg you can find -

5.2 QUESTION 1
Estimate the risk from L. monocytogenes in food when the number of organisms range from
absence in 25 grams to 1000 colony forming units per gram, or millilitre or does not exceed
specified levels at the point of consumption."
( http://www.who.int/f.../mra5_part5.pdf )

However there are also some specific raw data around if you search long enough, eg see the comment on Denmark (ca 1999) in -

http://groups.google...b80b32b03be24fc
(Not sure if this info. still valid now)

or for some general comments on pathogens in raw seafoods can look at -

http://www.fao.org/d...3e/y4743e05.htm

and

http://www.fao.org/d...3e/y4743e0n.htm

As indicated in above refs, one viewpoint of a tolerable raw level may be related to the ability to achieve a specified result subsequent to cooking.

Nonetheless I would not be at all surprised if a raw zero tolerance still exists for some locations.

I think yr last query overlaps various aspects, eg the sensitivity of other products in vicinity, specific products and their specs, company philosophy. As a result responses varied in my experience from 'panic' stations to ignoring the issue.

Rgds / Charles.C

Dear Val,

I think you are correct in that it is not easy to find definitive statements of official requirements for L.mono in raw seafoods. This is probably in part due to the fact that there was a very adverse general initial response which then became somewhat of an embarrassment when the 'natural'ubiquity became evident in many commercially traded seafoods together with detailed quantitative studies on the significance of L.mono. in RTE items.
As a result many countries 'decontrolled' L.mono from the tested pathogens in raw seafoods destined to be cooked before consumption.

The situation for some RTE items (but not all) is illustrated in these forums in the micro.criteria thread, eg you can find -

5.2 QUESTION 1
Estimate the risk from L. monocytogenes in food when the number of organisms range from
absence in 25 grams to 1000 colony forming units per gram, or millilitre or does not exceed
specified levels at the point of consumption."
( http://www.who.int/f.../mra5_part5.pdf )

However there are also some specific raw data around if you search long enough, eg see the comment on Denmark (ca 1999) in -

http://groups.google...b80b32b03be24fc
(Not sure if this info. still valid now)

or for some general comments on pathogens in raw seafoods can look at -

http://www.fao.org/d...3e/y4743e05.htm

and

http://www.fao.org/d...3e/y4743e0n.htm

As indicated in above refs, one viewpoint of a tolerable raw level may be related to the ability to achieve a specified result subsequent to cooking.

Nonetheless I would not be at all surprised if a raw zero tolerance still exists for some locations.

I think yr last query overlaps various aspects, eg the sensitivity of other products in vicinity, specific products and their specs, company philosophy. As a result responses varied in my experience from 'panic' stations to ignoring the issue.

Rgds / Charles.C

Added - one more comment is that the confused situation you have encountered is in my experience absolutely normal at the micro.end of the food business. There are some bacteria where you will find disagreements at the highest level over pathogenic significance although the regulatory requirements are completely uniform, eg salmonella (see the Cadbury's thread for an example of the possible ramifications). Often authorities take the 'Precautionary Principle' (guilty until proven innocent) which is understandable from a public health aspect (and politically impeccable). Subsequently opinions may then change but quite often it falls to commercial operations who have been impacted to promote official movements. Such issues prompted Simon to initiate the thread on micro. criteria which I recommend if not seen already -
http://www.saferpak....?showtopic=4590

(my apologies if you knew most of this already, I tend to talk too much)

Hi charles

Cheers for all the info and comments .....As for testing raw product for listeria ,from your comments and various other info i havae gathered I would consider it an unecessary procedure ......going forward it is the smoked salmon and environmental swabs that i wil send for listeria ... the salmon as its RTE and at least the environmental taken pre prodution will validate the cleaning .

I think i now have enough research on file to debate this issue should it arise during an audit.

THANKS!