AOAC Performance Tested Method 061503: Evaluation of the Listeria Environmental Detection Assay for Detecting Listeria spp. in Environmental Samples on the Atlas System

Introduction: Listeria is an environmentally ubiquitous organism implicated as a major cause of human foodborne illness worldwide. Listeria’s long lag phase and hindered growth in the presence of competitive flora presents a challenge for rapid and reliable detection with a single 24-hour enrichment step.

Purpose: To evaluate the Listeria Environmental Detection Assay for the detection of Listeria spp. on stainless steel, PVC plastic and sealed concrete surfaces in an AOAC Research Institute Performance Tested Method study.

Methods: The method included a single 24-h enrichment at 35°C in Half Fraser broth and was compared to the USDA-FSIS MLG 8.09 culture confirmation method. Selectivity was evaluated by testing 50 target microorganisms at 10X LOD and 30 non target microorganisms at > 10e8 CFU/ml. 

Results: The Listeria Environmental Detection Assay demonstrated statistical equivalence compared to the USDA-FSIS MLG 8.09 reference method for the detection of Listeria spp. on stainless steel, PVC plastic, and sealed concrete surfaces. The test method provided a positive result for 100% of 50 target microorganisms, and a negative result for 30 non-target microorganisms.

Significance: The Listeria Environmental Detection Assay can detect Listeria spp. after 24 hours of enrichment and offers a rapid, specific, and user friendly test method to monitor and limit contamination issues.