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P1-40 Assessment of Generic Listeria spp. and Listeria monocytogenes Occurrence in Apple and Stone Fruit Orchards

Monday, July 10, 2017
Exhibit Hall (Tampa Convention Center)
Ishani Sheth , U.S. Food and Drug Administration , College Park , MD
Darina Kantsavenka , U.S. Food and Drug Administration-CFSAN , College Park , MD
Hee jin Kwon , U.S. Food and Drug Administration , College Park , MD
Dohee Kim , U.S. Food and Drug Administration-CFSAN , College Park , MD
Jessica Palmer , U.S. Food and Drug Administration-CFSAN , College Park , MD
Abby Gao , U.S. Food and Drug Administration-CFSAN , College Park , MD
Anna Wooten , U.S. Food and Drug Administration-CFSAN , College Park , MD
Kari Peter , Department of Plant Pathology and Environmental Microbiology State Fruit Research and Extension Center , College Park , MD
Yi Chen , U.S. Food and Drug Administration , College Park , MD
Dumitru Macarisin , U.S. Food and Drug Administration , College Park , MD
Introduction:  Listeria monocytogenes (Lm) outbreaks linked stone fruits and to whole apples, used in producing caramel apples, highlights the potential for these fruits to serve as a vehicle in Lm transmission. Trace-back investigations of fresh produce-related outbreaks often implicated the growing environment as the source of contamination.

Purpose:  Examine the prevalence of generic Listeria spp. and Lm in preharvest production environments of apple and stone fruit.

Methods:  Fruits (apple and peach), leaves, soil, and surface water samples were collected from orchards in PA from July to October 2016. Samples were collected from orchards of early, mid and late season cultivars of apples and peaches. Listeria detection was conducted by selective enrichment in buffered Listeria enrichment broth, followed by streaking on MOX, ALOA, and RAPID’L.mono agars after 24 and 48 h of enrichment at 30°C. Presumptive Listeria positives were confirmed using API Listeria (bioMérieux).

Results:  Overall, 0.9% of the fruits (n=110) and 0.9% (n=207) of the preharvest environmental samples were positive for Lm. Major Listeria spp. present on fruits were Listeria grayi (0.9%) and Listeria welshimeri (1.8%). The incidence and prevalence of Listeria spp. in environmental samples was greater than that in fruits. Major Listeria spp. in environmental samples were L. grayi (1.9%), Listeria innocua (0.9%), L. welshmeri ( 0.9%), Listeria seeligeri (0.48%) and Listeria ivanovii (0.48%). Lm was not detected in the orchard pond.

Significance:  The potential exists for Lm contamination to enter packing houses on fruit or leaves at a low prevalence rate or through crates that were in contact with soil. Obtaining the baseline surveillance data on the occurrence of Listeria spp. and Lm in pome and stone fruit orchards will facilitate the development of preventive control strategies to reduce future recalls/outbreaks associated with these commodities.

Back to: Poster Session 1 – Viruses and Parasites, Beverages and Acid/Acidified Foods, Preharvest Food Safety, General Microbiology, Food Defense, Food Law and Regulation, Food Safety Systems, Food Processing Technologies, Modeling and Risk Assessment, Sanitation and Hygiene, and Antimicrobials
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