title: Early Recovery ofSalmonellafrom Food Using a 6-Hour Non-selective Pre-enrichment and Reformulation of Tetrathionate Broth.
abstract: Culture based methods are commonly employed to detect pathogens in food and environmental samples. These methods are time consuming and complex, requiring multiple non-selective and selective enrichment broths, and usually take at least 1 week to recover and identify pathogens. Improving pathogen detection in foods is a primary goal for regulatory agencies and industry.Salmonelladetection in food relies on a series of culture steps in broth formulations optimized to resuscitateSalmonellaand reduce the abundance of competitive bacteria. Examples of non-selective pre-enrichment broths used to isolateSalmonellafrom food include Lactose, Universal Pre-enrichment, BPW, and Trypticase Soy broths. Tetrathionate (TT) and Rappaport-Vassiliadis (RV) broths are employed after a 24-h non-selective enrichment to select forSalmonellaand hamper the growth of competitive bacteria. In this study, we tested a new formulation of TT broth that lacks brilliant green dye and has lower levels of TT . We employed this TT broth formulation in conjunction with a 6-h non-selective pre-enrichment period and determined thatSalmonellarecovery was possible one day earlier than standard food culture methods. We tested the shortened culture method in different non-selective enrichment broths, enumeratedSalmonellain the non-selective enrichments, and used 16S rRNA gene sequencing to determine the proportional abundances ofSalmonellain the TT and RV selective enrichments. Together these data revealed that a 6-h non-selective pre-enrichment reduces the levels of competitive bacteria inoculated into the selective TT and RV broths, enabling the recovery ofSalmonella1 day earlier than standard culture enrichment methods.
authors.affiliation: Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug AdministrationLaurel, MD, USA; Oak Ridge Institute for Science and TechnologyOak Ridge, TN, USA.
authors.forename: Ninalynn
authors.initials: N
authors.lastname: Daquigan
authors.affiliation: Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration Laurel, MD, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Grim
authors.affiliation: Resphera Biosciences Baltimore, MD, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: White
authors.affiliation: Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration Laurel, MD, USA.
authors.forename: Darcy E
authors.initials: DE
authors.lastname: Hanes
authors.affiliation: Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration Laurel, MD, USA.
authors.forename: Karen G
authors.initials: KG
authors.lastname: Jarvis
keywords: 16S rRNA; FDA BAM; Salmonella; metagenomics; selective enrichment; tetrathionate broth