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P3-220 Screening of Non-traditional Irrigation Water Sources for Shiga Toxin-producing Escherichia coli in the Mid-Atlantic Region of the United States: A Conserve Study

Wednesday, July 12, 2017
Exhibit Hall (Tampa Convention Center)
Joseph Haymaker , University of Maryland Eastern Shore , Princess Anne , MD
Fawzy Hashem , University of Maryland Eastern Shore , Princess Anne , MD
Salina Parveen , University of Maryland Eastern Shore , Princess Anne , MD
Eric May , University of Maryland Eastern Shore , Princess Anne , MD
Manan Sharma , USDA ARS Environmental Microbial and Food Safety Laboratory , Beltsville , MD
Chanelle White , University of Maryland Eastern Shore , Princess Anne , MD
Shirley Micallef , University of Maryland , College Park , MD
Maryam Taabodi , University of Maryland Eastern Shore , Princess Anne , MD
Amy Sapkota , Maryland Institute for Applied Environmental Health, University of Maryland, School of Public Health , College Park , MD
Introduction: Nontraditional irrigation water sources (NTIWS) have become a national priority with regard to agricultural water security. The NTIWS that are being analyzed for potential use on fresh produce are tidal and non-tidal surface water and reclaimed water. As a result of the Food Safety Modernization Act, agricultural producers must meet stricter guidelines regarding the quality of irrigation water used on fresh produce. 

Purpose: To evaluate the NTIWS for their physicochemical qualities and presence of Shiga toxin-producing Escherichia coli (STEC). 

Methods: The physicochemical qualities (temperature, dissolved O2, conductivity, pH, turbidity) were measured using an YSI EXO2 Multi-Parameter Water Quality Sonde. We developed and implemented a sampling apparatus which was used to filter the water samples through a modified cheesecloth membrane filter. Sixty samples were collected periodically in fall 2016 from six sites; 48 and 12 samples from four surface water sites (one tidal and three non-tidal) and two reclaimed water sites, respectively. Cheesecloth filters were enriched using universal pre-enrichment buffer followed by secondary enrichment in Non-O157 STEC enrichment broth.  Samples were streaked on Non-O157 STEC chromogenic plating medium and CHROMagar-O157. Presumptive STEC colonies were confirmed using an 11-plex traditional PCR for serotypes (O26, O45, O103, O111, O121, O145) and stx1, stx2, eae, ehx, and O157:H7.

Results: The sampling apparatus was successful and greatly enhanced sampling efficiency. One non-tidal site had two samples (~17%) positive for O45 and stx2 gene, while another non-tidal site had one positive sample (~8%) for stx1 gene. No samples were positive for O157:H7. No tidal or reclaimed water sites were positive for STEC. 

Significance: The sampling apparatus has the potential of greatly improving the sampling process of surface and reclaimed waters for bacterial detection. These results indicate low prevalence of STEC in NTIWS. Sampling is ongoing and will continue for an additional three years.

Back to: Poster Session 3 – Low-water Activity Foods, Packaging, Produce, Microbial Food Spoilage, Antimicrobials, Laboratory and Detection Methods, Water
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