Establishment of Standard Methods for Listeria monocytogenes Detection from Foods in Japan

In Japan, several standard methods have been established and published for detecting microbes from foods by "the Committee of the Methods for the Microbiological Examination of Foods (NIHSJ-MMEF)" since 2005. From the results of the Committee's activities, five of them became official Japanese methods including NIHSJ-08 and NIHSJ-09 which were first published in 2011 and 2014 based on ISO 11290-1 and ISO 11290-2 with some modifications. In this study, a working group consisting of five institutions was established to analyze that the modifications using CHROMagar ^TM Listeria was valid; the method developed was applicable for some Japanese foods such as minced tuna; and what the estimated limit of detection at 50% probability (eLOD₅₀) were. The eLOD₅₀ values were 0.744 CFU/25g for detection from Half-Fraser broth and 1.11 CFU/25 g for detection from Fraser broth, respectively. Finally, this study established and validated the parameters necessary for monitoring food contamination with Listeria monocytogenes (L. monocytogenes) in Japan.