What are Coliforms?

Hi all,


Question

What are coliforms. Are they the same as Entrobacteriaceae or different. Is E. Coli a colliform?


Thank you for your time..

Darsen

E.coli is an example of a coliform which are a group of gram negative bacteria within the family Enterobacteriaceae.

The major problems with testing for coliforms is the variability in definition of the term coliforms as they are defined usually by the method used for their detection.

In comparison the family Enterobacteriaceae is well defined taxonomically and methods for their enumeration are based on common properties.

The test for Enterobacteriaceae has replaced the tests for coliforms that traditionally have been used as indicators of hygiene and contamination after processing. Coliform testing is still used for water.

Dear Ken,

The test for Enterobacteriaceae has replaced the tests for coliforms that traditionally have been used as indicators of hygiene and contamination after processing.

This probably very much depends where you are located and the specific situation.

I do agree that I hv probably had more arguments over the years as to the measurement / interpretation of coliform data with respect to hygiene issues as any other micro. parameter (perhaps plate counts on a par). The arguments hv probably even increased since the development of more rapid evaluation tools, especially for low levels. Same comment for the so called faecal coliform also.

And, slightly , whether Enterobacteriaceae measurement offers a better route to assessment as compared to the specific determination of pathogens will similarly depend on what you are talking about.

Rgds / Charles.C

...
And, slightly , whether Enterobacteriaceae measurement offers a better route to assessment as compared to the specific determination of pathogens will similarly depend on what you are talking about.

Rgds / Charles.C

Dear Charles,

What are you talking about?
Can you please provide an example?

Regards,

FSSM

Charles

The reference re Enterobacteriaceae replacing the tests for coliforms came from a document I often refer to called

'Guidelines for the microbiological quality of someready-to-eat foods sampled at the point of sale'

It was by the UK Public Health laboratory Service issued in 2000 and updated by the Hygiene Protection Agency in 2009

A good document to have and the 2009 version can be downloaded at:

http://www.hpa.org.u...C/1259151921557

Dear Ken,

Many thanks for the link. I did not know that the previous excellent UK / RTE guidelines (referenced many times here) had been revised / updated. Was equally unaware that the Health Protection Agency existed, sounds like something out of George Orwell.

My first reaction was unfortunately overwhelmingly negative due to the disastrous format layout as I viewed it on a 14in screen ! They should remove the totally irrelevant photographs asap and then modify the column layout to minimise user eyestrain / need to rotate. I sort of mentally gave up half-way through.

This is only on the basis of a quick look but I got the impression compared to the last version that this production is rather striving to (politically?) conform to the EC jumbo directive(s) which came out after the previous PHLS/2000 guidelines. The fascinating legalistic info. in the previous edition has now vanished (disappearance of sovereign rights?) and the “Acceptable” column (= “an index reflecting a borderline limit of microbiological quality”) has now been re-edited / officially downgraded to “Borderline”. I love their new definition of “borderline” –“test results that are not unsatisfactory but are also not satisfactory, are on the upper limit of acceptability and which indicate the potential for development of public health problems and of unacceptable risk.”

I noted this peculiar, introductory statement –

These revised guidelines supersede those previously issued and have a different emphasis focusing on public health and consumer protection.

Best say no more perhaps.

Reverting to the immediate issue, I noted –

All Enterobacteriaceae are killed by the heat processes used in food production and should be readily removed from the factory, equipment and surfaces by appropriate cleaning procedures. Their presence in heat treated foods therefore signifies inadequate cooking or post-processing contamination.

Assuming “presence” = “detection” and inadequate = “unsatisfactory”, this comment seems inconsistent with the subsequent quantitative data, not to mention the typical regulatory situation. Or perhaps “inadequate” = “upper limit of acceptability”

Perhaps some further editing of the text would be beneficial.

Personally I hv never used “Enterobacteriaceae” since my customers / destinations hv required coliforms, E.coli et al. It seems to be regarded as a European oriented procedure (?). Nonetheless, hv nothing against it per se. (Long time ago evaluated VRBA for coliforms in homemade / bought systems and found unsuitable for my raw foods due massive false positives; will depend on the situation of course). The pluses and minuses of all these inter-related indicators can be examined in great detail by googling “enterobacteriaceae compendium microbiological examination food”. Prepare for a long read.

@FSSM – My comment related to philosophical / practical viewpoints on assessing the safety of food, ie how to decide is satisfactory or not ? For example, some opinions resist any rejection of food on safety grounds unless a specific pathogen is isolated. However practical or statistical limitations may hinder this option, eg the assessment of water supplies or in some factories it is simply not allowed to do in-house pathogen testing.These kind of problems overlap the whole subject of relevance / implementation of microbiological criteria.

added - I should hv noted that the basic data looks similar (identical?) to the previous edition but with updated EC interpretations and follow-ups. The material has also been expanded in certain areas. The previous editions are, IMO, an absolutely superb collection of guidelines for RTE products and this will no doubt maintain that reputation, especially if it becomes more easy to read.

Rgds / Charles.C

Thanks for the clarification Charles.C

FSSM