THE slime that coats water pipes could be a haven for bacteria that cause
stomach ulcers and gastric cancer, according to researchers at Robert Gordon
University in Aberdeen.
Helicobacter pylori has been implicated in a wide variety of
gastrointestinal diseases, from stomach inflammation to ulcers and even cancer.
In developed countries, half of people over 50 years old carry the bacterium in
their guts, and in developing countries an even larger proportion of people are
affected. Several animals may harbour the microorganism, but so far no one has
found a reservoir in the environment.
Donald Reid and his colleagues in Scotland thought that H. pylori
might thrive in biofilms. These form when microorganisms colonise surfaces such
as the insides of water pipes, often surrounding themselves with a sticky
protective film. “Biofilms occur naturally in all water distribution systems,”
The researchers grew a biofilm inside stainless steel pipes in the laboratory
and inoculated it with H. pylori. Even after unchlorinated water was
flushed through the pipes for 192 hours, H. pylori still infested the
biofilm. The team’s findings will be published in the Journal of Applied
“Anywhere there is a biofilm, there is a potential haven for Helicobacter
pylori,” says Reid. This is particularly likely in unchlorinated private
wells and water supplies in developing countries. Although most public supplies
in developed countries are chlorinated, Reid believes the bacteria could still
survive inside the biofilm. “Chlorine is only going to attack the upper layers,”
he says. “By the time those are destroyed, the chlorine is gone.” As the biofilm
builds up, Reid says that bacteria may be washed away a few at a time or
occasionally released as large clumps.
A spokesman for Severn Trent, one of the largest suppliers of drinking water
in Britain, says there are no studies that show H. pylori in treated
water, so it is not included in routine water testing. “If a study showed it in
treated water, we would want to investigate further,” says the spokesman.