3 replies to this topic

[Sumudu]

Hi All,
Testing of ground beef (in ready to cook burger production) for E-coli 0157.H7 was shown as negative, but the result shows an E-coli contamination. It could be another Serotype. I thinking about the possible ways of contamination of another Serotypeof E-coli . Anyway, Beef trimmings were tested for E-coli 0157.H7 by supplier. your comments on this scenario is highly appreciated.
Thanks..
Sumudu

[Charles.C]

Hi All,
Testing of ground beef (in ready to cook burger production) for E-coli 0157.H7 was shown as negative, but the result shows an E-coli contamination. It could be another Serotype. I thinking about the possible ways of contamination of another Serotypeof E-coli . Anyway, Beef trimmings were tested for E-coli 0157.H7 by supplier. your comments on this scenario is highly appreciated.
Thanks..
Sumudu

Dear Sumudu,

Well, as you no doubt are aware, the usual interpretation of a detection of generic E.coli is simply a history (somewhere) of direct/indirect fecal contamination. This is not exactly a rare event for a variety of raw materials although the significance is obviously also related to the quantitative level of the finding.

Overall, there are at least 699 other strains to choose from. Try this post (and the equally interesting thread IMO) for details - http://www.ifsqn.com...dpost__p__46472

As noted in links in above post, most of the strains are not pathogenic to humans, presumably one of the reasons why “generic” E.coli is still acceptable to be used only as an indicator rather than a specific pathogen.

For meat specifically, the situation in USA over the classification of “saleable” meat has apparently just changed (this month), particularly regarding the “Big Six” pathogenic strains of E.coli –
http://www.care2.com...t-industry.html

The conclusion is apparently based on analysis of raw beef manufacturing trimmings.

Rgds / Charles.C

PS - related risk profiles / procedures are discussed and cross-linked in link below (taken from previous reference above) -
https://www.federalr...w-beef-products

[poppysnoss]

Hi All,
Testing of ground beef (in ready to cook burger production) for E-coli 0157.H7 was shown as negative, but the result shows an E-coli contamination.

This is not unusual. Testing for E. coli often use methods based on BS ISO 16649-1 or 16649-2, using TBX agar. These methods detect the beta-glucuronidase enzyme, which is specific to E.coli. 96 - 97% of E. coli strains produce this enzyme.

The chromogen in TBX medium is 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide and is targeted by this enzyme. However, E. coli 0157:H7 does not produce the beta-glucuronidase enzyme and therefore is not detected using this test.

Hope this helps.

Pops

Edited by poppysnoss, 15 June 2012 - 10:23 AM.

[MicroMike]

Most likely source of E. coli in beef is faecal contamination.Two common routes are that the cattle's hide is soiled with manure and as the hide is being pulled (removed) it either touches the surface of the carcass or dried tag showers the carcass as the hide comes off (especially if the hide is pulled from the head to the tail and the carcass is hung by the back legs)The other big source is when the guts are nicked as the carcass is eviscerated thus directly contaminating with manure.Beef trim is particularly problematic because it's all from the carcass surface (most likely to be contaminated)
There are several hundred E. coli; most are harmless. The ones to worry about have a key set of virulence genes and can export one or both types of stx toxin. These are referred to as verocytotoxic E. coli.
HTH
Mike