Rapid Detection of Listeria in Food

Listeria monocytogenes is the most important human pathogen species of the genus Listeria. It causes the disease listeriosis which can be severe especially if older people, humans with weakened immune system or pregnant women and their child are infected. Findings of L. monocytogenes are notifiable in several EU countries. The EU Rapid Alert System for Food and Feed (RASFF) published over 1000 notifications of Listeria in food in 2016. Mostly fish, sea food, meat or dairy products were affected. Also findings in fruit, convenience food or other products were reported.

Because of the high pathogenicity of this microorganism, a consistent monitoring of food is necessary. According to Commission Regulation (EC) No 2073/2005 on microbiological criteria for foodstuffs, the manufacture of the product shall conduct studies in order to investigate compliance with the food safety criteria throughout the shelf-life. In particular, this applies to ready-to-eat foods that are able to support the growth of Listeria monocytogenes.

In order to prevent that unsafe food is placed on the market and to discharge the food business operator’s duty of care, release testing gain more and more in importance when it comes to preventative identification of potential unsafe food. It is possible to simulate the development of L. monocytogenes with challenge tests.

A fast communication of the results is essential in this risk-based monitoring process of food testing. In case of negative results, classical microbiological analyses require up to five days. Molecular biological methods like the detection of DNA via PCR (polymerase chain reaction) reduce the turnaround time significantly.

With the newly developed PCR method „BACGene Listeria“, exclusion of Listeria monocytogenes as well as Listeria spp. is possible in a very short time. Depending on the date of sample reception, a submission of negative results is possible within 24h (incl. enrichment). Positive findings subsequently have to be confirmed via culture. BACGene Listeria kits are certified by AFNOR Certification as an alternative method for Listeria monocytogenes and Listeria spp. detection according to EN ISO 16140 (s. http://nf-validation.afnor.org/en/food-industry/listeria-monocytogenes/ and http://nf-validation.afnor.org/en/food-industry/listeria-spp/).