Presence of Listeria monocytogenes in Mediterranean-Style Dry Fermented Sausages

Abstract

The morphological, physiological and epidemiological features of L. monocytogenes, together with the severity of human listeriosis infections, make L. monocytogenes of particular concern for manufacturers of cold-stored “ready to eat” (RTE) foods. L. monocytogenes has been isolated from a wide variety of RTE foods and is responsible for several outbreaks associated with the consumption of RTE meat, poultry, dairy, fish and vegetable products. Although L. monocytogenes is among the most frequently-detected pathogens in dry fermented sausages, these products could be included in the category of RTE products in which the growth of L. monocytogenes is not favored and have rarely been implicated in listeriosis outbreaks. However, L. monocytogenes is highly difficult to control in fermented sausage processing environments due to its high tolerance to low pH and high salt concentration. In many Mediterranean-style dry fermented sausages, an empirical application of the hurdle technology often occurs and the frequent detection of L. monocytogenes in these products at the end of ripening highlights the need for food business operators to properly apply hurdle technology and to control the contamination routes of L. monocytogenes in the processing plants. In the following, through an up-to-date review of (personal and un-) published data, the main aspects of the presence of L. monocytogenes in Mediterranean-style dry fermented sausages will be discussed.

Occurrence of Listeria monocytogenes in Ready-to-Eat Meat Products and Meat Processing Plants in Spain

“…Once introduced into the plants, L. monocytogenes can persist over time in the processing environment. Not surprisingly, L. monocytogenes is among the most frequently detected pathogens in meat products, and several studies have documented the incidence of the pathogen reaching prevalence levels of up to 40%–45% [1]. …”

“…According to a recent review by Meloni [1], the level of contamination by L. monocytogenes in food and non-food contact surfaces in meat processing environment ranges between 17%–50% and 11%–25%, respectively. The present study showed that 22.72% of work surfaces tested positive for L. monocytogenes .…”

“…Even when L. monocytogenes is initially present in small quantities in a foodstuff, it can multiply at varying rates during chilled storage depending on the type of food product, both under aerobic and anaerobic conditions, adapt to disinfectants and adhere to various surfaces [1]. The ability of L. monocytogenes to multiply in various foods at temperatures as low as 2 to 4 °C makes the occurrence of L. monocytogenes in ready-to-eat (RTE) foods, such as cooked, raw-cured and dry-cured salted meat products, of particular concern [2,3,4].…”

“…Food-contact surfaces can represent a significant hazard, especially if microbial aggregates, known as biofilms, have formed attached to the work surfaces [6]. L. monocytogenes has biofilm forming ability, which could be an important cause for its persistence in food processing environments [1]. In fact, many studies have shown that L. monocytogenes is able to adhere to and form biofilms on surfaces in contact with food such as polyethylene, polyvinyl chloride, glass and stainless steel [7,8].…”

Listeria monocytogenes and enterotoxigenic Staphylococcus aureus in dry fermented sausages belonging to “Traditional Agri‐Food Product” produced in Southern Italy

“…The risk of post‐treatment contamination is much more likely to occur during the production of typical and traditional dry fermented sausages; the association of artisan practices, and the poor hygienic conditions that could be present in processing plants often close to the farm, may result in contamination and survival of foodborne pathogens (Meloni, ; Panagou, Nychas, & Sofos, ).…”