Application of Sample6 DETECT™ HT/L Kit for the Detection of Listeria in Mixed Leafy Greens

Abstract

Background: Early and accurate detection of Listeria in foods is vital. Current methods require 24 h enrichment for detection. Objective: This study aimed to demonstrate enhanced early detection of Listeria in mixed leafy greens using Sample6 DETECT™ HT/L, a phage-based detection system. Methods: A method comparison between the reference method (U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 10) for the detection of Listeria spp. and the Sample6 DETECT HT/L using a new proprietary R2 Medium was performed in mixed leafy greens. Results: Using the R2 Medium enrichment with Sample6 DETECT HT/L, detection of L. innocua was possible at 12 h (with a centrifugation step), and L. monocytogenes was detected by 18 h, with equivalent performance as the 24 h enrichments using the reference method detection. The Sample6 DETECT HT/L gave an equivalent performance for L. innocua at 15 h as the reference method at 24 h. Detection was accomplished by the addition of reagents in the kit, following the package insert, and reading results in a detection chamber using a 96-well plate reader that detects a fluorescent signal. Conclusions: Results indicate the new R2 Medium and Sample6 DETECT HT/L allowed for earlier detection of Listeria spp. in mixed leafy greens. Highlights: Sample6 DETECT HT/L with the new R2 Medium allowed the early detection of Listeria spp. and may be applied in other food matrices and environmental samples.

The Application of Bacteriophage Diagnostics for Bacterial Pathogens in the Agricultural Supply Chain: From Farm-to-Fork

“…11,53 The kit was marketed at $16 for a 10 sample kit in 2016 11 ; the assay's reporting time is 6 h and therefore holds potential for production line microbial detection. The Sample 6 Detect HT/L has been recently verified for testing produce such as ice cream, 54 leafy greens, 55 and environmental stainless-steel surfaces, 56 with results comparable with culture methods commercially used and a reduced reporting time. Listeria phage detection holds the potential to improve on gold standard methods in both farm and food processing infrastructures in a variety of matrices.…”