Taq Man Real Time PCR detection of Listeria monocytogenes: a study of enrichment incubation time affecting sensitivity in experimental dry fermented sausages

Abstract

Listeria monocytogenes is a facultative intracellular Gram positive, catalase positive bacterium, ubiquitous in nature and capable of causing listeriosis in humans and animals. Conventional microbiological techniques and modern molecular approaches are currently used for the isolation and detection of Listeria monocytogenes in food samples. The aim of this study was to investigate the infl uence of enrichment incubation time on the sensitivity of Taq Man Real Time PCR method. For that purpose, dry fermented sausages were artifi cially inoculated with serial dilutions of L. monocytogenes ATCC 19111. The obtained results indicated that incubation time is an important factor affecting the sensitivity of Real-Time PCR detection. The best results were obtained after 24 h of pre-enrichment, with primers and probe complementary to the listeriolysin (hlyA) gene, when it was possible to detect less than 10 CFU/g of L. monocytogenes.