Early Recovery of Salmonella from Food Using a 6-Hour Non-selective Pre-enrichment and Reformulation of Tetrathionate Broth

• Published in: Frontiers in microbiology Vol. 7; p. 2103
• Main Authors: Daquigan, Ninalynn, Grim, Christopher J, White, James R, Hanes, Darcy E, Jarvis, Karen G
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 27.12.2016; Frontiers Media S.A
• Subjects: 16S rRNA; BASIC BIOLOGICAL SCIENCES; FDA BAM; metagenomics; Microbiology; Salmonella; selective enrichment; tetrathionate broth; FDA BAM; tetrathionate broth; 16S rRNA; Salmonella; selective enrichment; metagenomics
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2016.02103

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. detection in food relies on a series of culture steps in broth formulations optimized to resuscitate and reduce the abundance of competitive bacteria. Examples of non-selective pre-enrichment broths used to isolate from 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 for and 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 that recovery was possible one day earlier than standard food culture methods. We tested the shortened culture method in different non-selective enrichment broths, enumerated in the non-selective enrichments, and used 16S rRNA gene sequencing to determine the proportional abundances of in 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 of 1 day earlier than standard culture enrichment methods.