Diagnostic capabilities of modern methods of determination pathogenic listeria in meat products

Abstract

Annual reports on the morbidity of the adult population report outbreaks of listeriosis caused by Listeria monocytogenes with clinically pronounced febrile gastroenteritis. The main transmission route to humans is believed to be through consumption of contaminated food, especially ready-to-eat meat products. Rapid and specific detection of L. monocytogenes in food is critical for ensuring the safety of consumers. The aim of this work was to study the occurrence of L. monocytogenes in vacuum-packed meat products using modern diagnostic methods. In total, 60 vacuum-packed meat products were studied using real-time PCR (iQ-Check™ realtime PCR kit), immunoassay (VIDAS LMO2 test) and culturing. Thirty-two of 60 (53%) vacuum-packed meat products were L. monocytogenes positive by real-time PCR. The occurrence was especially high in heat-treated sausages (80%). Only two products (two bacons) were VIDAS and culture positive. Additionally, L. monocytogenes was isolated from one heat-treated sausage, which was VIDAS negative. All VIDAS and culture-positive samples were also PCR positive. In two (12%) out of 17 vacuum-packed ready-to-eat products, the number of L. monocytogenes was over 100 cfu/g demonstrating that the shelf life assigned to some vacuum-packed products is not appropriate. Real-time PCR based on iQ-Check™ realtime PCR kit was shown to be very sensitive to detect L. monocytogenes in foods and thus a useful tool for screening.