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

J AOAC Int. 2020 Jan 1;103(1):156-160. doi: 10.5740/jaoacint.18-0238.

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.