How Probiotics Can Prevent Disease
of Article: http://www.sciencedaily.com/releases/2009/04/090401200433.htm
(Apr. 2, 2009)
— Using probiotics successfully against a number of animal diseases has
helped scientists from University College Cork, Ireland to understand some
of the ways in which they work, which could lead to them using probiotics
to prevent and even to treat human diseases.
Presenting the work at
the Society for General Microbiology meeting in Harrogate April 2, Dr Colin
Hill described how his team had used three animal models of disease that have
human counterparts – bovine mastitis, porcine salmonellosis (a
gastrointestinal disease) and listeriosis in mice (an often fatal form of
food poisoning) – to demonstrate the protective effects of probiotics.
"Rather than use
commercially available probiotics, we made our own probiotic preparations
containing safe bacteria such as Lactobacillus species newly isolated from
human volunteers" said Dr Hill, "In all three animal diseases we
observed a positive effect in that the animals were significantly protected
The team also used
probiotics to control disease in animals that were already infected. The
results of these tests proved that administering these safe bacteria to an
infected animal was as effective as the best available antibiotic therapies
in eliminating the infectious agent and resolving the symptoms.
In each instance the
protection was linked to a particular bacterial species, and the mechanism
of action varied from direct antagonism (where the probiotic directly kills
the pathogenic bacteria) to effects mediated by the host immune system. For
example Lactobacillus salivarius UCC118 protected mice against listeriosis
(a disease which can affect pregnant women) by producing an antimicrobial
peptide that eliminates Listeria monocytogenes in the gut of the animal. In
another mechanism, Lactococcus lactis could be used to treat mastitis by
eliciting an immune response that overwhelmed the infectious bacterium.
Dr Hill added, "It
is likely that using probiotics rather than antibiotics will appeal to
at-risk individuals since they are safe, non-invasive, do not create
resistant bacteria and can even be administered in the form of tasty foods
"We have shown that
we can protect and even treat animals against pathogenic bacteria by
introducing harmless bacteria at the site of the infection," said Dr
Hill. "In order to use similar strategies in preventing or treating
human disease we must understand the molecular basis of their efficacy.
This understanding will provide the basis for intelligent screening and
selection of the most appropriate protective bacterial cultures to go
forward into human trials".
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