ABSTRACT
A validation study of the 3M Petrifilm Environmental Listeria (EL) Plate (3M Food Safety, St. Paul, MN) was conducted at Q Laboratories, Inc., Cincinnati, OH. The method was compared to the Health Canada MFHPB-30 reference method for the analysis of stainless steel environmental surfaces. Twenty replicates of the environmental surface were analyzed at a low and a high inoculum level. The low-level sampling area was inoculated with 0.2-2 CFU/5 cm2, and the high-level sampling area was inoculated with 2-5 CFU/5 cm2. Five control replicates were also analyzed at 0 CFU/5 cm2. There was no significant difference in the number of positives detected by the 3M Petrifilm EL Plate method and the Health Canada MFHPB-30 reference method for the environmental surface analyzed in this study.
Subject(s)
Bacteriological Techniques/methods , Bacteriological Techniques/standards , Environmental Microbiology/standards , Listeria/isolation & purification , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
A validation study of the 3M Tecra Listeria Visual Immunoassay (VIA; 3M Food Safety, St. Paul, MN) was conducted at Q Laboratories, Inc., Cincinnati, OH. The 3M Tecra Listeria VIA method was compared to the Health Canada MFHPB-30 reference method for the analysis of five ready-to-eat (RTE) meats: deli turkey, hot dogs, liver pate, raw fermented sausage, and deli ham, and on a stainless steel environmental surface. Twenty replicates of each of the five food matrixes were analyzed at a low and a high inoculum level. The low-level test portions were inoculated with 0.2-2 CFU/25 g, and the high-level test portions with 2-5 CFU/25 g. In addition, 20 replicates of one environmental surface were analyzed at a low and a high inoculum level. The low-level sampling area was inoculated with 0.2-2 CFU/5 cm2, and the high-level area with 2-5 CFU/5 cm2. Five control replicates were also analyzed at 0 CFU/25 g (uninoculated) for the foods and at 0 CFU/5 cm2 for the environmental sampling area. There was no significant difference in the number of positives detected by the 3M Tecra Listeria VIA and the Health Canada MFHPB-30 reference method for four of the RTE meats and the stainless steel environmental surface analyzed in this study. For the raw, fermented sausage, there was a significant difference in the number of positives detected for the high inoculum level by the 3M Tecra Listeria VIA and the Health Canada MFHPB-30 reference method, with the 3M Tecra Listeria VIA method detecting more positives.
