Affiliation:
1. Division of Food Processing Science and Technology, U.S. Food and Drug Administration , 6502 South Archer Rd. , Bedford Park, IL 60501, USA
2. Institute for Food Safety and Health, Illinois Institute of Technology , 6502 South Archer Rd. , Bedford Park, IL 60501, USA
Abstract
Abstract
Background
Sprout growers in the United States are required to test spent sprout irrigation water (SSIW) or in-process sprouts for Escherichia coli O157:H7 and Salmonella species. Pathogen screening kits are commercially available; however, few have been validated for analysis of sprouts or SSIW.
Objective
This study evaluated AOAC-certified test kits (lateral flow devices [LFDs], enzyme immunoassays [EIAs], and molecular assays) in comparison with culture methods described in the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) for detection of Salmonella and E. coli O157:H7 in alfalfa SSIW.
Method
Twenty-five milliliter aliquots of alfalfa SSIW, either uninoculated or inoculated with Salmonella or E. coli O157:H7 at a low (∼0.5–0.7 CFU/25 mL) or high level (∼10–20 CFU/25 mL), were subjected to the enrichment and assay protocols recommended by each test. Pathogen presence was confirmed following FDA BAM procedures and, if applicable, test kit manufacturer protocols.
Results
Twelve of the 13 Salmonella test kits evaluated (except VIDAS UP) performed well and detected Salmonella in 100% of SSIW samples contaminated at 0.61 CFU/mL. Performance varied among E. coli O157:H7 test kits, with four (Reveal, MicroSEQ, GDS, MDA) of 12 kits designed for next-day detection, and four (Reveal, VIP Gold, MicroSEQ, GDS) of seven kits designed for same-day detection capable of detecting the pathogen in 100% samples contaminated at 0.90 CFU/mL.
Conclusions
Enrichment conditions play a key role in determining the performance of test kits and the success of confirmation.
Highlights
This study is the first to compare a wide range of commercial test kits for detection of Salmonella and E. coli O157:H7 in SSIW.
Funder
U.S. Food and Drug Administration and the Institute for Food Safety and Health
Illinois Institute of Technology. C. Chrysogelos was supported by the Oak Ridge Institute for Science and Education (ORISE) Research Participation Program
Publisher
Oxford University Press (OUP)
Subject
Pharmacology,Agronomy and Crop Science,Environmental Chemistry,Food Science,Analytical Chemistry