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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #337559

Research Project: Characterization and Mitigation of Bacterial Pathogens in the Fresh Produce Production and Processing Continuum

Location: Environmental Microbial & Food Safety Laboratory

Title: Evaluation of Listeria monocytogenes survival and infectivity in non-traditional agricultural waters

Author
item Gartley, Samantha - University Of Delaware
item Vanore, Adam - University Of Delaware
item Craighead, Shani - University Of Delaware
item Sharma, Manan
item Kniel, Kalmia - University Of Delaware

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Introduction: Listeria monocytogenes (Lm) is an enteric bacterium that can be found in environmental reservoirs. Restricted water availability for agriculture has increased interest in surface and reuse water sources which could potentially transmit Lm. Purpose: Persistence and infectivity of Lm recovered from brackish tidal water (TW) and vegetable wash water (VW) were compared. Methods: Water was collected from the Mid-Atlantic region at two sites in Fall 2016. Lm (environmental isolate from 2011 outbreak associated with cantaloupes) was inoculated into collected volumes at 8.62 log CFU/ml, all in triplicate, which were held for ten days at 16°C to mimic irrigation water temperatures during harvest. Lm was recovered on Brilliance Listeria Agar (BLA) on days 0, 3, 5, 7, and 10. Cell culture infectivity was performed with recovered Lm from day 10 was inoculated onto human ileocecal monolayers (HCT-8) for 30 min, washed with HBSS, treated with 10µg/mL gentamicin sulfate for 30 min, and incubated at 37°C for one hour after which infective Lm cells were recovered and enumerated on BLA. Statistical analysis was performed by one-way ANOVA and t-test. Results: Initial populations of Lm were 8.62±0.32 log CFU/ml on day 0 across water samples. By day 7, Lm populations had significantly (p < 0.,05) declined by 2.46±0.41 log CFU/ml in VW compared to those in TW. Lm populations in TW remained at 8.33 ±0.16 at day 7. Infectivity assay data from Lm showed that Lm recovered from BPW on day? infected HCT-8 cells at 5.06±0.32 log CFU followed by Lm recovered from VW on day ? at 3.97±0.36log CFU, slightly greater than Lm recovered from TW on day ? at 3.36±0.95 log CFU. Significance: Lm inoculated into surface and vegetable wash waters showed decreased viability and decreased infectivity as demonstrated in a cell culture assays.