Information on Faecal Coliforms

Derek Law dlaw at idgplc.com
Thu Feb 22 04:08:23 EST 2001


In reply to question 1, I would liketo point out the following. Water
microbiologists only recognise two types of  coliform,  E. coli ( lactose
+ve at 44C or B-glucuronidase +ve) and faecal coliforms (lactose +ve at 37C
but not 44C and glucuronidase negative). Coliforms such as Proteus, Hafnia
which are lactose negative are not included in the definition. These
definitions are different to those used by clinical microbiologists.

E. coli doesn't normally occur in the environement except as a consequence
of faecal pollution. However, the persistence of this organism will vary
considerably depending on the temperaure degree of organic matter present in
the water. Thus is may be possible to isolate E. coli  from water days or
weeks after a pollution event given the right conditions.

The position with faecal coliforms is slightly different, these can be found
as natural members of water flora in small numbers so their presence in
water is not a definitive indicator of faecal pollution. However, their
presence in high numbers is likely to be indicative of pollution but in such
cases E. coli is likely to be present.

There are other indicators of faecal pollution, enterococci and sulphite
reducing clostridia. These are also indicators of faecal pollution, their
numbers in faeces are lower than coliforms so they are not as sensitive
indicators of pollution as coliforms however, they survive better in water
than coliforms and so their presence in water in the absence of coliforms is
indicative of faecal pollution some time in the past.

It is important not to consider just mammals (particularly human and farm
and animals) as sources of faecal pollution of water. In the North west of
England, in Morecambe Bay, there are huge numbers of migrant and indigenous
birds which live in the bay. It has been suggested that these birds
contribute considerably to the faecal load in the sea in this area. This is
the probable cause of the failure of many of the beaches in the locality to
fail bacteriological tests for quality.

Feacal coliforms are not found to any great extent in air except perhaps in
a toilet where aerosols may be generated when a toilet is flushed.

Hope this helps

Derek Law

Company Microbiologist
LabM




"DEAN JARVIS" <Dean.Jarvis at sydneywater.com.au> wrote in message
news:sa93dfab.069 at gwdomawt-nrs.sw.com.au...
Hi,
I've got a few questions that I was hoping someone might be able to help me
with.
1. Do faecal coliforms exist naturally in water ways or are they only
present when warm blooded animal excretions are present?

2. Does anyone know the journal no. for the article in Nature or New
Scientist that talked about the survival characteristics of fc in waterways?

3.. Does anyone know how prevalent fc are in the air, from human breath
(what I'm trying to determine is the viability of some new fc filtration
equipment that doesn't have a lids)?

Regards DEan


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