Streamlined Listeria monocytogenes test slashes detection time for food samples

Food safety researchers have developed a streamlined testing workflow capable of detecting low levels of Listeria monocytogenes in food samples in just eight hours, significantly faster than traditional methods, which can typically require up to three days.

The new workflow, recently published in Microbiology Spectrum, could help food manufacturers and testing laboratories respond much faster to potential contamination, reducing the risk of outbreaks and costly product recalls. This is especially important, as FDA data analysed by global labelling and supply chain solutions provider Loftware shows that Listeria contamination was the second most common cause of food recalls in 2024, accounting for 14.69 percent of incidents. 

Dr Min Lin, research scientist at the Canadian Food Inspection Agency and lead author of the study, explained that existing laboratory methods can take between 24 and 72 hours to confirm the presence of Listeria monocytogenes. The new process aims to cut this drastically, moving from sample collection to actionable result in a single working day.

Combining multiple technologies into a single process

The method combines multiple technologies into a single process, integrating culture enrichment, filtration-based sample preparation, magnetic separation of target bacteria and real-time PCR (polymerase chain reaction) detection. Researchers tested the system on ground beef samples artificially contaminated with extremely low levels of L. monocytogenes, as few as 1 to 5 cells in a 25-gram sample. Despite the low contamination level, the system successfully detected the pathogen within eight hours.

Rapid detection of Listeria is critical for food manufacturers, especially given its high mortality rate of 20 to 30 percent among those who contract listeriosis. This bacterium thrives in food processing environments and can contaminate ready-to-eat foods, posing a serious public health risk.

“Once the streamlined procedure is evaluated thoroughly and implemented in food microbiology testing laboratories, it will significantly reduce the turnaround time for Listeria monocytogenes testing in food samples,” said Dr Lin. “Future research will focus on evaluation of the described workflow for the detection of various L. monocytogenes strains in various food matrices, especially in naturally contaminated foods.”

Lin hopes the study will also encourage the development of fully automated systems, requiring minimal manual handling, to further improve efficiency in food safety testing.

For food manufacturers and technical teams, faster Listeria detection not only enhances product safety but could also reduce the need for precautionary recalls and product holds, helping protect both consumers and brand reputation.