Rapid detection of Salmonella enterica in fresh produce by a novel microarray-based PathogenDx system

Authors: YIN, HSINBAI - US Department Of Agriculture (USDA); CHEN, CHI-HUNG - US Department Of Agriculture (USDA); BOOMER, ASHLEY - US Department Of Agriculture (USDA); NEWLAND, CORY - Collaborator; MAY, MELISSA - Collaborator; KATCHAMN, BENJAMIN - Collaborator; Patel, Jitu

Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/26/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Introduction: Consumption of fresh produce contaminated with Salmonella enterica may result in significant risk of foodborne illnesses. The diverse matrices pose great challenges for rapid Salmonella detection. Purpose: The purpose of this ongoing study is to determine and work to improve the efficacy of PathogenDx microbial detection system in rapid detection of low Salmonella contamination in fresh produce. Methods: Fresh produce (N=96) including spinach, kale, arugula, Romaine lettuce, and Iceberg lettuce were spiked with Salmonella enterica Newport at two inoculation levels of 1 and 5 CFU/25 g sample. Spiked samples were enriched and concentrated by three methods prior to the microarray analysis. Centrifugation and concentrator methods, spiked samples were enriched with 225 ml of universal pre-enrichment broth (UPB) for 3 h at 37°C. After enrichment, samples were concentrated by Innovaprep concentrator (100 ml/sample) or centrifugation (10 or 50 ml) at 10,000 rpm for 20 min. Filtration procedure, 225 ml of PBS mixed with spiked sample was filtered through 0.45 µm filter. The filter was enriched in 10 ml UPB for 3 h at 37°C. Following concentration, samples (1 ml/test) were analyzed by microarray-based PathogenDx identification system to detect the presence of Salmonella. Samples were simultaneously analyzed by the FDA-BAM Salmonella detection procedure. Results: All samples spiked with 5 CFU of Salmonella were detected by PathogenDx system following centrifugation of 10 ml volume or concentration by Innovaprep pipette; and 87.5% by membrane filtration method. At 1 CFU/sample level, the system detected up to 75% of the spiked samples when concentrated by centrifugation, Innovaprep concentrator or membrane filtration. The FDA-BAM method that requires 24-h enrichment detected all spiked samples at 100%. Significance: This novel approach may be used for rapid detection of Salmonella in fresh produce.