Quantification of Listeria monocytogenes in fermented sausages by MPN-PCR method

AIMS: To combine the principles of most-probable-number (MPN) statistics and the conventional PCR technique to enumerate Listeria monocytogenes in fermented sausages. METHODS AND RESULTS: A simple method to enumerate L. monocytogenes in fermented sausages was developed and compared with direct plating in Palcam agar. Species-specific MPN-PCR, but not direct plating, made the enumeration of L. monocytogenes possible in all assayed samples. CONCLUSIONS: MPN-PCR proved to be a rapid and reliable method for enumerating L. monocytogenes in fermented sausages, including low contaminated samples. SIGNIFICANCE AND IMPACT OF THE STUDY: This MPN-PCR technique may facilitate the enumeration of L. monocytogenes for routine analyses in fermented sausages without excessive work.