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Precautionary measures in the wake of the listeriosis outbreak

Issued by Perfect Word Consulting (Pty) Ltd

Across South Africa, the outbreak of the food-borne disease Listeria has been reported as possibly being the largest outbreak of its kind the world has ever seen. This disease has already claimed more than 170 lives. According to The National Health Laboratory Service, 915 cases of Listeria have been reported since January 2017. Those most vulnerable are young people, the elderly and those with compromised immune systems.

John J Coetzee, CEO at Green Worx Cleaning Solutions states; “It is pivotal that we take proper care in cleaning our foods, particularly fresh produce. The Listeria monocytogenes bacterium is found in the water and soil and can contaminate the foods we eat, either through the soil or from manure used as fertiliser. The best defence against this outbreak is to make sure that everything that goes through your kitchen is cleaned and disinfected.”

Extra precaution is needed as Listeria is not a disease that is immediately identified. It has a three-week incubation period which makes recognition of contamination difficult. Coetzee explains that livestock can carry the bacterium unnoticed, leading to contamination of foods of animal origin such as meats and dairy products.

“Listeria comes about via a biofilm which is created by an accumulation of bacteria that develop a protective matrix made up of organic polymers (EPS): polysaccharides and proteins. It is this organic matrix which is very difficult or even impossible to remove using conventional cleaning and disinfection protocols. However, biofilms are the dominant environment for microorganisms. One thousand to 10 000 times more bacteria grow in a biofilm compared to in a planktonic (free) state. Furthermore, bacteria encased in a biofilm can be 1 000 times more resistant to disinfectants (biocides) than planktonic bacteria. To ensure optimal hygiene levels, it is therefore necessary to eliminate these biofilms,” continues Coetzee.

Due to the existence of the biofilm it is not enough to only use disinfectants, as these disinfectants are ineffective against the biofilm bacteria’s organic matrix. It is, therefore, necessary to use products that can degrade the organic matrix in conjunction with a disinfectant. Odorite Ultra Enzymatic Deep Clean 30 x, for example, is currently the only product in South Africa that is effective in this process. “According to the Directorate of Food Control, Odorite Deep Clean Enzymatic is the only enzyme product on the market that is SABS 1828 approved for the purpose of cleaning hard surfaces and CIP in food industries,” adds Coetzee.

“It is necessary to use a complex and highly specific enzymatic cocktail to achieve the destruction of the biofilm matrix. This eradicates the protective biofilm matrix. Conventional cleaning is not able to degrade this matrix. Once the protective matrix has been eliminated, the bacteria are left without any protection. A disinfection phase is then applied to destroy the bacteria which has become planktonic and, therefore, accessible to disinfectants (biocides),” explains Coetzee.

According to scientific expert, Coghan (2016), enzyme-based detergents are used to improve the efficacy of disinfectants against bacterial biofilms. Enzymes can target cells in the biofilm matrix and can cause the matrix to become looser and break up. They can also trigger cell release actions in the biofilm enveloped cells, causing many cells to break off from the biofilm. Enzymes have some role in targeting the bacterial cells encased within a biofilm.

The main function of enzymes is to degrade the lipid, carbohydrate and DNA components of the extracellular matrix, severing the links between cells and subsequently separating them, allowing rapid deterioration of the biofilm integrity. Disinfectants can then act more powerfully to kill cells that were once embedded in the matrix of the biofilm EPS and can also target released cells which have been forced into the planktonic state by the enzymes action.

“Using a product to wash fresh produce that can break down the biofilm matrix, together with a disinfectant, is the best weapon against the Listeria outbreak. This, combined with the effective sanitation of any areas where food is prepared (residentially or commercially) will have a positive impact on the fight against listeriosis,” concludes Coetzee.