Since its initial outbreak in 2017, Listeria monocytogenes has been an ongoing challenge in South Africa, and food testing laboratory and food safety consultancy Food Consulting Services Laboratories director Grant Lawrence argues that it is important that the food sector puts stringent control mechanisms in place to eradicate it.

Listeria monocytogenes is a pathogenic bacterium that causes the infection listeriosis. It is a highly resistant bacterium, capable of surviving in the presence or absence of oxygen and, unlike other pathogens, is extremely tolerant to cold temperatures, he explains.

The removal of this bacterium is a significant challenge for many food processing facilities because it commonly hides in rusty and damaged items and other inaccessible places. Although originally found in meat-processing facilities, the bacterium has spread to dairy and vegetable processing plants.

The spread of Listeria can be curbed when considering plant design, as this should eliminate areas where these bacteria can harbour such as crevices, apertures, and nooks and crannies.

All the food-handling equipment should be of food-grade material – usually stainless steel – and as smooth and sealed as possible to minimise the possibility of Listeria getting into factories, adds Lawrence.

Listeria is also much more tolerant to salt and a wide range of pH levels; therefore, salt and acidity in the food will not restrict its growth as much as they would most germs.

The correct maintenance of fridges needs to be ensured by keeping them as cold as possible, ideally below 4 °C, Lawrence maintains, adding that Listeria is easily destroyed by heat and removed by most sanitisers.

The main factor is good hygiene practices, implemented systematically using protocols such as hazard analysis and critical control points. This protocol defines where the risks lie and stipulates systematically removing them at the most appropriate point, referred to as the “critical control point”.

Further, there are equivalent standards –called good agricultural practices, or GAP – in the agriculture sector, such as offered by the United Nations’ Food and Agricultural Organisation, that need to be upheld.

The South African regulatory authorities need to ensure that a food-borne bacterium like this does not spread again, using effective quality and safety assurance systems, says Lawrence.

“Food companies need to develop the correct attitude towards food safety and implement a strong food safety culture where food safety becomes a non-negotiable. Such a system should be continuously monitored, corrected and improved as need be. Cost saving and profit can never trump food safety, as this always leads to trouble,” he concludes.