Although Listeria monocytogenes was recognized as a cause of human disease for more than 7 years, it was not until the 1980s that food borne association as realized and accepted. The number of Listeria outbreaks is large.
The number of voluntary recalls by food processors due to know or suspected Listeria – contaminated food products, is even larger.
Listeria has exceptional growth conditions. The organism grows well on minimal nutrients, and at temperature raging from 1 to 45 °C, and can grow in biofilms that coat surfaces and prevent Listeria from being removed by cleaning or killed by disinfectants. It can grow at pH range 4.4 to 9.6.
Listeria can produce biolfim on a variety of surfaces commonly used in food processing plants, including stainless steel, nylon, teflon and polyester floor sealer.
Although Listeria monocytogenes is frequently present in raw meat the pathogen is of higher concern for the safety of products that may be consumed without further cooking.
Occurrence of the pathogen in cooked ready to eat products is predominantly due to recontamination during handling procedures such a slicing and packaging.
Listeria contamination in meat and meat products
