Rapid Detection of Escherichia coli O157:H7, Non-O157 STEC and Salmonella, in Contaminated Meat Using LAMP MP Molecular Test and Lateral Flow Assay

Introduction: Rapid detection of foodborne pathogens is an essential feature of any detection method used in food industry. In this study we present data for the detection of Escherichia coli O157:H7, Salmonella spp., (AOAC approved method) and non-O157 STEC (Shiga Toxigenic E. coli) using LAMP molecular detection kit and a simple lateral flow assay.

Purpose: The objective of this study is to emphasize the importance of simple, easy-to-use, cost effective and rapid immuno-assays that can help in speedy time-to-result testing of food samples.

Methods: Pure culture dilutions were tested with the kit and lateral flow assays to determine the limit-of-detection (LOD). For enrichments, ground beef/turkey, beef trim and chicken carcass samples were obtained from local stores and inoculated with 0 CFU, 2 CFU and 10 CFU/sample. Samples were enriched in SAS^TM Enrichment media and tested using SAS^TMMolecular detection kit and lateral flow assay.

Results: The LOD for the kit and lateral flow assays were determined by testing pure culture dilutions. For E. coli O157:H7 and Salmonella spp., the LOD for LAMP and lateral flow assay is 2 x 10³ CFU/ml and 1 x 10⁶ CFU/ml, respectively. For non-O157 STEC, the LOD for the kit and lateral flow assay is 1 x 10¹-10³ CFU/ml and 1 x 10³-10⁵CFU/ml, respectively (depending on the strain).

In 6 hours enriched samples, the kit assay can detect E. coli O157:H7 and Salmonella spp., to as low as 1 CFU/sample inoculation and non-O157 STEC to as low as 2 CFU/sample inoculation. The lateral flow assays for E. coli O157:H7 detect as low as 2 CFU/sample inoculation, non-O157 STEC can detect as low as 2 CFU/sample inoculation. Lateral flow assay for Salmonella spp., was able to detect as low as 10 CFU/ml in 16-20 hour enrichment samples.

Significance: The data presented here shows that a simple and rapid lateral flow assay can be used for rapid and easy detection of bacteria in contaminated meat without the need for any costly equipment thus aiding in faster time-to-results.