21 April 2020

Handheld gadget detects food poisoning twice as fast and 200 times cheaper


Identifying a source of food poisoning typically requires days to weeks. Now, researchers from the University of Copenhagen have devised a method that is at least twice as fast and 200 times cheaper than traditional methods. The chocolate bar-sized device is currently being tested by several companies.

Photo: Oxford Nanopore Technologies
Photo: Oxford Nanopore Technologies

University of Copenhagen researchers have developed a method that can save time and funds for hospitals, the food industry and public agencies as they hunt for a bacteria responsible for a food poisoning outbreak.

To locate the source of a Salmonella, Listeria or other type of bacterial outbreak that is at the root of a food poisoning outbreak, DNA analyses of suspected bacteria are often conducted. While DNA analysis is faster than previous methods, it remains time-consuming and expensive. One can opt for cheaper methods of analysis, that are slow and provide very limited information about the bacteria - or deploy traditional methods, which provide more detailed information, but are time-consuming and require millions of kroner worth of equipment that must be operated by specialists.

"Our method allows us to identify bacteria down to the strain level for only seven kroner (€1) per sample, as opposed to the hundreds of kroner per sample needed today. And, whereas DNA analysis using traditional methods takes several days to weeks, ours takes about eight hours - and we anticipate achieving realtime results," explains Lukasz Krych, researcher and associate professor at the University of Copenhagen’s Department of Food Science.

The research article is published in the journal Communications Biology.

Smaller than a bar of chocolate

Lukasz Krych's method is run by a small handheld device that sequences bacterial DNA. The device is smaller than a bar of chocolate and can be connected to either a mobile phone or laptop. It is produced by Oxford Nanopore Technologies and costs roughly 6,000 kroner (€930).

"I see it as a low-cost, fast-screening method for hospitals that need to rapidly identify the source of a staphylococcal outbreak, for example, or a food processor that needs to identify where unwanted bacteria are hiding out along a production line. Food agencies can also benefit from the method," says Lukasz Krych, adding:

"The detective work is always a race against time as a factory continues to produce goods that poison its consumers. The longer it takes to identify a source and analyze data, the more people become sick."

Lukasz Krych and Josue L. Castro Mejia from the Department of Food Science are loading the small device with DNA material.

Lukasz Krych and Josue L. Castro Mejia from the Department of Food Science are loading the small device with DNA material.

99.6 percent accuracy

The method, called ON-rep-seq, does not just identify the bacteria, but also whether it is from the same or a different bacterial strain. This is important information in the event of a food poisoning outbreak.

"For example, it is crucial to know whether the strain of Listeria found in a patient's feces is the same as the strain found in a suspected package of smoked salmon. Our method can tell you just that," says Lukasz Krych.

DNA material from a sample is placed into the small device, where it passes through so-called nanopores. Within these nanopores, a highly advanced sensor captures every letter of the bacteria’s genetic code. The device can analyse hundreds of bacteria at once.  

Instead of sequencing a bacterium’s genome as traditional methods do, this method merely examines select fragments of genetic material. In doing so, both time and money are saved. At the same time, the analysis is 99.6% accurate.

The method is now being used and tested by several companies.