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P2-182 Can Corn Oil Serve as an Additive to Help Increase the Recovery of Salmonella enterica in Oregano?

Monday, July 27, 2015
Exhibit Hall (Oregon Convention Center)
Junia Jean-Gilles Beaubrun , U.S. Food and Drug Administration , Laurel , MD
Nicole Addy , Oak Ridge Institute for Science and Technology , Oak Ridge , TN
Marie-Laure Flamer , JIFSAN , College Park , MD
Laura Ewing , U.S. Food and Drug Administration , Laurel , MD
Gopal Gopinath , U.S. Food and Drug Administration , Laurel , MD
Karen Jarvis , U.S. Food and Drug Administration , Laurel , MD
Christopher Grim , U.S. Food and Drug Administration , Laurel , MD
Darcy Hanes , U.S. Food and Drug Administration , Laurel , MD
Introduction: In recent years, spices have increasingly been associated with outbreaks of Salmonella, underscoring the need for enhanced surveillance and an improved outbreak response.  Spices, like vegetables, fruits, and medicinal herbs, are known to possess phenolic compounds that are associated with antimicrobial effects and properties. Subsequently, the presence of these antimicrobial compounds may impede the detection of Salmonella that persists in dried products.

Purpose: The goal of this study was to evaluate the effects of adding corn oil in growth media as a compound to sequester the antimicrobial compounds found in spice, while allowing Salmonella to grow during pre-enrichment culture.

Methods: Oregano samples were artificially contaminated with Salmonella enterica, pre-enriched in modified Buffered Peptone Water with and without 2% (vol/vol) corn oil and incubated overnight at 37°C. Samples were transferred to selective enrichment broth of Rappaport-Vassiliadis and tetrathionate and plated on Xylose-Lysine-Tergitol 4 Agar and various other chromogenic agars. The positives plates were examined for Salmonella colonies as described in the FDA Bacteriological Analytical Manual, and suspect colonies were confirmed using the colorimetric Gram Negative card and Vitek® 2 Compact, software Version 5.  In addition to the plating method, molecular approaches such as molecular serotyping PCR, and shot-gun metagenomics were used to assess the increase in recovery of Salmonella.

Results: From the 30 samples processed for each condition tested, an average 283 CFU/ml of Salmonella was recovered in samples artificially contaminated with Salmonella grown in mBPW with corn oil as compared to the 17 CFU/ml without the corn oil. The results demonstrated that addition of corn oil increased the recovery of Salmonella by ≥ 50% in oregano samples.

Significance: The addition of corn oil in the pre-enrichment broth may also enhance the recovery of Salmonella from other spices that contain antimicrobial compounds, a crucial step that may enhance detection using both traditional culture and molecular methods of contaminated spices.

Back to: Poster Session 2 – Laboratory and Detection Methods; Meat, Poultry and Eggs; Dairy and Beverages; Food Law and Regulation; General Microbiology; Modeling and Risk Assessment
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