Researchers Develop Test to Find Campylobacter in Chicken Flocks

A Danish university has developed a way to use air sampling to identify Campylobacter-positive chicken flocks.
September 9, 2021

The Technical University of Denmark’s National Food Institute has pioneered a test method that has quadrupled the chances of detecting Campylobacter in chicken flocks, and stopping the spread of infection before it enters the meat supply chain.

What is Campylobacter?

Campylobacter is a bacteria that infects the intestinal tract. Like Salmonella, it’s common for chickens, ducks and other poultry to carry Campylobacter, as the bacteria can live naturally in the intestines of these animals and be passed through their droppings. Animals often show no signs of infection, making Campylobacter very hard to detect until well after meat is already in the food supply.

People usually fall ill with campylobacteriosis after eating raw or undercooked poultry or something that touched it. The primary symptom in humans is diarrhoea.

In 2019, Denmark saw a marked surge of Campylobacter infections. That year there were 5,389 recorded infections, an increase of 18 percent from the previous year. These cases were largely caused by infected chicken flocks.

Campylobacter bacteria also cause the majority of food-borne illnesses in Europe, prompting the Danish researchers to focus on cheaper and more timely testing methods.

Sock method currently used in testing

The “sock method” of testing for the presence of Campylobacter involves the tester putting gauze around their footwear, then walking through the chicken house so any bacteria will be trapped on the gauze. That gauze, or “sock,” is then placed in a growth medium where bacteria can multiply for 48 hours. Another 48-hour period is required before testers can accurately determine whether the flock is infected.

This means four days are needed using the sock method.

Quicker, more efficient technique

The new testing method was developed as part of the European Union’s AIR-SAMPLE project. It yields results in just 2 hours.

The method uses a sort of mini-vacuum cleaner with a special filter that collects bacteria where chickens are housed. The filter is subsequently analysed with a polymerase chain reaction (PCR) test. A PCR test separates DNA to isolate Campylobacter bacteria and find out whether it’s present and in what quantities.

Researchers used chickens from Norway as a control group, as Norwegian chicken flocks typically test negative for Campylobacter. No infections were found in the Norwegian flocks. Researchers found that the new method uncovers infection in 4 times more chicken flocks than the sock method.

Why is this breakthrough important?

If flocks with Campylobacter are pinpointed before arriving at the slaughterhouse, they can be slaughtered after the flocks without the bacteria, preventing cross-contamination throughout the entire production line.

With infected chicken meat being a major cause of this illness, a fast and effective method of testing for Campylobacter is crucial.

Campylobacter infection is not limited to the European Union — campylobacteriosis is also the most commonly reported cause of foodborne illness in Australia. Food safety developments taking place around the world directly impact the health and safety of Australia’s food supply.