Listeria Screening

The culture-dependent detection of Listeria monocytogenes in food is a time consuming procedure due to consecutive enrichment steps for at least 24 hours. The reference method according to ISO 11290-1 needs about five days to obtain a presumptive positive result. The optimization of nutrient media and enrichment protocols allow a faster and more precise detection. Particularly the food industry needs rapid methods with high sensitivity and specifity. These performance criteria enable food business operators to react just in time in case of pathogen-positive samples and further ensure the safety of food along the food supply chain network. Two commercial rapid methods for the detection of L. monocytogenes are evaluated for performance criteria relevant for the food industry. Further, the reference method according to ISO 11290-1 is applied for comparison purposes. Different types of food prone to harbour L. monocytogenes e.g. smoked salmon are applied for testing purposes. According to ISO 16140 the amount of samples tested positively for the target pathogen needs to be at least 50%. Hence, inoculation trials are integrated in the study to ensure this target value. Selected L. monocytogenes strains from various sources are applied. Finally, it is aimed to show that alternative methods are a capable tool for the reliable monitoring of L. monocytogenes in different types of food.