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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 #337556
Research Project: Characterization and Mitigation of Bacterial Pathogens in the Fresh Produce Production and Processing Continuum

Location: Environmental Microbial & Food Safety Laboratory

Title: Persistence and transmission of Escherichia coli and Salmonella in a watermelon field ammended with poultry itter: year two

Author
item DE MELO RAMOS, THAIS - University Of Delaware
item CRAIGHEAD, SHANI - University Of Delaware
item SPANNINGER, PATRICK - University Of Delaware
item MARIK, CLAIRE - University Of Delaware
item JOHNSON, GORDON - 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:Poultry litter (PL) is a nutrient-rich soil amendmentfor crop production; however, use of PL in soils may introduce enteric pathogens tofruits and vegetables. Purpose:This study was to evaluated the persistence of a non-pathogenic rifampicin-resistant E. coli strain (TVS 355) and the presence of naturally occurring Salmonellain soil, soil amended with PL, and on field-grown watermelons. Methods:From May-October 2016, 12 individual plots were seeded with‘Exclamation’ and ‘Liberty’ watermelons planted on plastic mulch.Plots were unamended, unamended andinoculated with E.coli, amended with PL, or amended withE. coliinoculated-PL. Soil samples were collected weekly (n=348). Watermelons (n=108)were swabbed at harvest.Samples were analyzed for E. coli populations by direct plating or MPN, and for Salmonella by MPN using RV and TT broth or byenrichment using a modified FDA BAM procedure.. Results:By day 8, E.coli levels were significantly (p<0.0001) greater in PL-amended soils (5.02 log CFU/ gdw (gram dry weight) compared to unamended soils(3.98 log CFU/gdw), and remained that way throughout the study.By day 120, E. coli populations in PL-amended soils were greater (1.15±0.66 log CFU/gdw) compared to those in unamended plots which were below (0.12±0.01 log CFU/gdw). Salmonella spp. was detected in 59% of soil samples. The meanSalmonella populations recovered from PL-amended and unamended plots were 1.90±1.10 log MPN/g and 1.85 ± 1.08log MPN/g, respectively..Salmonella spp. was detected on watermelons(28/108) grown in both amended and unamended soilscontainingE. coli populations of 1.95 to 2.81 log MPN/g.Approximately 92% of watermelons sampled were positive for E.coliwith a highest recovery of 3.32 log (MPN/g) from amended-soils. Significance:PL-amended soils provided conducive environments for E. coli persistence through growing seasonsand facilitate transfer to watermelons,but did not contain higher populations of Salmonella spp. compared to unamended soils.