Methods of Enrichment and Compositing of Environmental Samples for Detection of Listeria monocytogenes

Scientists from the FDA published in J Food Prot (84 (4): 639–646, 2021) published a comparison of methods for the enrichment and detection of Listeria spp. and Listeria monocytogenes from environmental samples. Different enrichment procedures involving buffered Listeria enrichment broth (BLEB), University of Vermont medium (UVM), and Fraser broth (FB) were evaluated to determine the limits of detection (LODs) for L. monocytogenes and to assess the efficacy of composite sampling by wet (pooling of primary enrichments) and dry (pooling of swabs) procedures. A single-step BLEB yielded 0.33 CFU/225 ml, and two-step UVM-FB enrichment yielded 0.49 CFU/225 mL. The use of either two-step BLEB-FB or UVM-FB enrichments for stainless steel swabs yielded similar growth of L. monocytogenes. Compositing L. monocytogenes from culture up to 1:7 (1 positive sample to 7 negative samples) worked well. The BLEB-FB method allowed significantly faster detection (after 24 h of FB incubation) in composites of 1:4 and 1:7 samples compared with the UVM-FB method. @ https://meridian.allenpress.com/jfp/article-abstract/84/4/639/448753/Evaluation-of-Methods-of-Enrichment-and?redirectedFrom=fulltext