Scientists from University College Cork (Ireland) have been using probiotics successfully against a number of animal diseases. This has helped them to understand some of the ways in which they work -- this knowledge could lead to new probiotics that prevent and even treat human diseases.
Presenting his work at the Society for General Microbiology meeting in early April, 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.
“In all three animal diseases, we observed a positive effect in that the animals were significantly protected against infection," said Dr. Hill, whose team had blended their own probiotic substances together specifically for these experiments.
Probiotics were also used to control disease in animals that were already infected. The results of these tests proved that administering 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
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 or beverages”.