Successful laboratory trials of a new sanitising teat spray to prevent mastitis in dairy cows signalled a new approach to control bacterial disease in animals.
Professor Greg Cook from Otago University’s microbiology and immunology department describes the increasing resistance to the suite of antibiotics as a looming pandemic but researchers are looking for alternative ways to control bacterial diseases.
Antibiotics used in humans are effectively the same compounds as used in animals and plants.
Resistance to these drugs has been increasing because of their misuse, especially in poultry and animal feedlots where the drugs are used at sub-therapeutic levels to stave off infections and improve productivity.
Cook said the theory is that one infected hen could wipe out the whole colony.
“Because they don’t use a sledge hammer to control bacteria but a tack hammer, you end up with the general population of animals resistant to antibiotics.”
Using antibiotics on animals has been banned in the European Union since 1988 as constant exposure to sub-therapeutic doses allowed bacteria to develop resistance.
That resistance found its way to humans via the food chain.
There has also been misuse of antibiotics in humans adding to the problem.
“People go on about inappropriate use of antibiotics in animals but there is also an issue with inappropriate use of antibiotics in humans as well,” he said.
The solution to growing resistance is to break the link between antibiotics used in humans and those used in animals so Otago University researchers are looking at a new therapeutics approach to prevent disease in livestock.
Cook calls this approach green anti-microbial, which could see new weapons developed to control bacteria for disease such as footrot, Psa, Mycoplasma bovis, kauri dieback, Johne’s disease, methane production in ruminant animals, nitrous oxide and nitrogen leaching.
“All these are bacteria pathogens in the environment and the tools we have got are pretty toxic, not good for the environment, not very effective or do not offer anything.”
The green anti-microbial process involves scientists developing an assay to target a particular bacterium.
It is then screened against natural products to find a product that kills the pathogen.
From there chemists and pharmacists develop a formulation that is then tested in the field.
That process was followed to develop a new sanitiser teat spray with animal health products company Deosan, to prevent mastitis.
The candidate product has shown promise in the laboratory.
Patents have been applied for and Cook said field tests are proposed later his year and should they confirm the laboratory success, it could be available commercially in 2020.
Mastitis control is a $280 million a year business and teat sanitisers are based on one of two key ingredients, which heightens the risk of bacteria developing resistance.
One of those ingredients, chlorhexidine, is listed by the World Health Organisation as an essential medicine.
It is widely used as a hand sanitiser in hospitals and rest homes.
But Cook said these newly developed anti-bacterial products will only ever be used in animals so break that link that can enhance resistance.
But, just as importantly, the work and processes used in developing the new teat spray have applications for new products to control other forms of bacteria.
“This shows we can develop a brand new compound that is needed exclusively in the animal sector and importantly we don’t see any resistance and it is effective.”
Although some time off, those new products could have implications as diverse as controlling kauri dieback, footrot and Mycoplasma bovis.
Sanitiser footbaths have been established in the kauri forests for visitors to wash their shoes and prevent the spreading of the spores killing the giant trees. But it is not killing the bacteria.
Cook said green anti-microbial products could also have a role battling new organisms that breach biosecurity controls.
“We could build a drug discovery pipeline to control pathogens and protect species that are important to us.”
The hunt for new antibiotics has taken on new urgency with forecasts burgeoning food sectors in China, Brazil and India will increase the overall use of antibiotics in animal production by 70% by 2030.
Cook has applied for funding to continue his research.
The project had been boosted by the success after just a year with the sanitiser.
Normally there is a very low pass rate of products to reach this stage.
Another option being investigated is to repurpose old drugs for use in animals.
Cook said farmers needed assurance the growing issue of antibiotic resistance in humans does not mean they are going to be left without health products for their stock.
“I want to tell farmers people are working on this.
“They will not be left without anything.”
