Why does Listeria monocytogenes survive in food and food-production environments? Original paper

What was reviewed?

This review examined the survival mechanisms of Listeria monocytogenes in food and food production environments. It focused on the bacterium’s ability to withstand various environmental stress factors, such as extreme temperatures, low water activity, pH variations, and disinfectants. Additionally, it explored how Listeria persists in these environments, contributing to food contamination risks.

Who was reviewed?

The review focused on Listeria monocytogenes, a foodborne pathogen responsible for listeriosis, and its ability to survive and adapt to harsh conditions typically found in food processing environments. It discussed how different strains of Listeria, including those frequently isolated from food products and environments, exhibit various survival strategies.

What were the most important findings?

The review highlighted Listeria monocytogenes’ remarkable ability to survive in adverse conditions such as cold, high salinity, low water activity, and even in the presence of ultraviolet light and heavy metals. Listeria can grow at temperatures ranging from -0.4°C to 45°C and tolerate pH levels between 4.6 and 9.5. These traits contribute to its persistence in food processing facilities, even in the face of cleaning and sanitation efforts. The bacterium can also form biofilms on food production surfaces, which protect it from cleaning agents and other stress factors. Persistent strains, especially of serotype 1/2a and 1/2b, were found to have strong biofilm-forming capabilities and were commonly linked to food production environments. The review also emphasized that certain strains are genetically adapted for survival, with mechanisms like biofilm formation, resistance to disinfectants, and cold and heat shock proteins that enhance their persistence. Notably, resistance to benzalkonium chloride (BAC), a common disinfectant, was also linked to Listeria‘s ability to survive in food-processing environments despite sanitation measures.

What are the greatest implications of this review?

The review’s findings underline the challenges of managing Listeria monocytogenes in food production environments. The ability of Listeria to form biofilms and resist common disinfectants makes it difficult to completely eliminate from food facilities, posing ongoing food safety risks. The review calls for more effective cleaning protocols and highlights the need for stricter monitoring and improved hygiene practices to prevent contamination. It also suggests that understanding the genetic adaptations and resistance mechanisms in Listeria can inform better strategies to mitigate foodborne outbreaks, particularly in facilities producing ready-to-eat foods.