RULING THE ROOST - NANOTECH TACKLES FOOD POISONING

More than four million Australians suffer from food poisoning each year, many due to bacterial contamination of poultry products. Now nanotechnology is being tested as an alternative to antibiotic use in chickens prior to processing.

It’s a story that will be familiar to many of us. Possibly it started with a night out with friends: a few drinks, good company and, seemingly, great food. But later on, maybe that night or perhaps the following morning, it starts. The cold sweat, stomach pain, the vomiting and nausea. You’ve got a bout of food poisoning.

Caused by eating food contaminated with bacteria, viruses or even chemicals, more than four million Australians suffer from food poisoning every year. While most people view food poisoning as something that isn’t too serious, maybe requiring a day in bed, symptoms in severe cases can progress to high fever and respiratory failure, particularly in more vulnerable people such as infants and the elderly. The cost of food poisoning to the Australian economy is estimated to be more than $1 billion per year.

Bacteria are responsible for the majority of food poisoning outbreaks in Australia. In the right conditions, some bacteria can double their numbers every 20 minutes, so if a piece of meat is left out on the bench on a warm day and it contains 100 food-poisoning bacteria, in just over 3 hours that same meat could now contain more than 50,000 bacteria! Bacteria thrive in warm conditions, particularly at human body temperature (37°C), so it only takes a small amount of bacteria to be ingested in contaminated food for it to multiply and consequently cause illness.

Two of the main culprits when it comes to bacterial food poisoning are Campylobacter and Salmonella. A number of different foods can carry these bacteria; in particular, uncooked poultry is a major source of these bacteria. Ironically these bacteria occur naturally in the gut of chickens and generally do not affect the health of the animals. It’s when they make their way into our gut that problems arise. However, during the process of producing chicken meat it’s possible for it to become contaminated with Salmonella and Campylobacter bacteria. While there has been a huge effort to try and sanitise the processing of chicken meat to eliminate bacterial contamination, many scientific studies have shown that they still persist in low numbers.

Given the relatively high incidence of food poisoning in Australia it’s curious to note that most bacterial contamination of poultry can be eradicated by appropriate cooking and handling. Health departments at both state and national levels alongside poultry industry representatives have developed extensive education programs and fact sheets to encourage proper cooking of animal products, yet the problem still persists. For instance, in late 2015 a 5-star hotel in Melbourne was at the centre of a food poisoning outbreak and in early 2016 a café on Victoria’s Great Ocean Road had a similar outbreak.

Coupled with the obvious distress that this causes their patrons, restaurants and the like can face expensive and lengthy litigation. Indeed food poisoning victims in the United States have now started pointing the finger at the primary producers in addition to the eateries from which they fell ill.

In order to reduce the risk of bacterial food-borne illness there is a necessity to reduce the original bacterial levels in meat chickens prior to processing. The lower the numbers of these bacteria at the beginning of the process line, the easier it will be to minimise the bacterial levels at the end of the process.

A great deal of work is now being done in an attempt to reduce the continual bacterial infection and re-infection that occurs during the movement and processing of chicken meat. Efforts include increasing awareness, improving sanitation,disinfecting and improving farm management practices.

While these efforts will go some way to limit the spread of food poisoning bacteria, they don’t deal with reducing the original bacterial load in the chicken itself.

While there is potential to reduce the Campylobacter and Salmonella load with specific anti biotics, chickens need to be free of antibiotics before processing to ensure there is no trace of such compounds in the chicken meat. In addition, the increase in antibiotic-resistant bacteria is causing concerns globally, and this has resulted in the reduction or, in some cases, ban of anti - biotic use in livestock industries. New interventions aimed at reducing the contamination of poultry meat are required to significantly reduce the incidence of illness in humans.

One such new intervention could involve nanotechnology, which applies to things 100 nm or less in size. Specifically designed nanoparticles could be used to bind to food-poisoning bacteria in such a way as to inhibit or even prevent the growth of the bacteria. These nanoparticles would be in the form of single-stranded DNA or RNA molecules that are able to bind to specific targets, including proteins and peptides, with high affinity and specificity. Nanoparticles have already been used to regulate cellular processes and to guide drugs to their specific cellular targets.

Nanotechnology has already been used to detect many different bacterial pathogens, including Campylobacter and Salmonella. While these studies demonstrated that it’s plausible to generate nanoparticles with high binding affinity and specificity for Campylobacter and Salmonella, they have only used this technology as a way of detecting the presence of the bacterium.

This new application of nanotechnology has the potential not only bind to Campylobacter but also to inhibit its growth. Such technological advances will provide a new intervention method to reduce the load of Campylobacter prior to processing chicken meat, and consequently reduce the incidence of food poisoning.

Recently we were awarded a Rural Industries Research and Development Corporation grant of more than $1 million to tackle this problem. In collaboration with Dr Sarah Shigdar at Deakin University we will spend the next 3 years investigating new ways to suppress the growth of Campylobacter in chickens prior to processing. Using nanotechnology, the aim of the project will be to generate a cheap, specific and reliable way of reducing or even stopping the Campylobacter load in meat chickens prior to processing, ensuring an overall reduction and hopefully elimination of Campylobacter, and ultimately a decline in human illness caused by Campylobacter infection.

Specifically the project will target several strains of Campylobacter, and will ultimately be delivered to chickens in their drinking water. There is also the potential to be able to use the same technology to generate strain-specific tests to detect Campylobacter in poultry. This approach also has the potential to be used to reduce the levels of other food-poisoning bacteria such as Salmonella.

The financial cost of food-borne illness is a burden on the Australian economy. The losses in productivity and the cost in terms of medical intervention, not to mention the impact upon individuals, is significant. Campylobacter is a major contributor to such illness, and while Campylobacter loads in poultry can be controlled with the use of antibiotics, this strategy has drawbacks in terms of the rise of antibiotic resistance as well as consumer perceptions.

The generation of a novel antimicrobial, in the form of a nanoparticle treatment, that could specifically reduce the Campylobacter and/or Salmonella load of poultry prior to processing would have the potential to reduce the number of food poisoning cases in Australia. Apart from the clear economic benefit of such a reduction in disease rates, it would benefit the poultry industry by increasing the product’s safety in the eyes of the consumer and hopefully reduce the number of days we all spend in bed feeling sick and sorry.

By Tamsyn Crowley & Ben Wade in "Australian Science", volume 381, number 4, July/Ausgust 2017, excerps pp. 33-35. Digitized, adapted and illustrated to be posted by Leopoldo Costa.

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