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ARS Home » Research » Publications at this Location » Publication #112393
Title: A STUDY OF U.S. ORCHARDS TO IDENTIFY POTENTIAL SOURCES OF ESCHERICHIA COLI 0157:H7

Author
item Riordan, Denise
item Sapers, Gerald
item HANKINSON, T - EPL TECHNOLOGIST
item MAGEE, M - EPL TECHNOLOGIST
item Burke, Angela - Mattrazzo
item Annous, Bassam

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2001
Publication Date: 3/6/2001
Citation: N/A

Interpretive Summary: The association of unpasteurized apple cider with Escherichia coli 0157:H7 has led to interest in determining potential sources of this pathogen in the orchard. Fourteen U.S. orchards were surveyed in autumn 1999 to determine the incidence and prevalence of E. coli 0157:H7, and other microflora, including generic E. coli bacteria. Fruit samples, soil, water rand fecal samples were collected. Fruit was also tested for internalization of microflora. No E. coli 0157:H7 was found. Generic E. coli was detected in soil and water, and in 6% of fruit samples, all collected from areas previously designated as high-risk. Microflora counts were higher in dropped and damaged fruit (<0.05) and in orchards associated with fecal contamination or proximity to pastures (P<0.05). Generic E. coli was not found to be internalized. Findings suggest that dropped and/ or damaged fruit should not be included in fruit designated for the production of unpasteurized juice. Further research is ongoing to evaluat the risks associated with close proximity of orchards to pastures.

Technical Abstract: The association of unpasteurized apple cider with Escherichia coli 0157:H7 foodborne illness has led to increased interest in potential reservoirs of this pathogen in the orchard. Fourteen U.S. orchards were surveyed in Autumn 1999 to determine the incidence and prevalence of E. coli 0157:H7, generic E. coli, total aerobic microflora, and yeasts and molds. Fruit samples (n=63) (8 apple and 2 pear varieties), soil, water and fecal samples were collected. Samples were plated on (a) Tryptic Soy Agar for total aerobic count (b) E. coli/coliform Petrifilm for total coliforms and generic E. coli, and (c) Yeast and Mold Petrifilm. Samples positive for coliforms and generic E. coli were enriched and tested for E. coli 0157:H7. Fruit was also tested for internalization of microflora by aseptically removing the core, stem and calyx areas and individually assessing for the categories of microflora listed above. No E. coli 0157:H7 was found. Generic E. coli was detected in soil and water, and in 6% of fruit samples (1 apple and 3 pear samples), all collected from areas previously designated as high-risk in this study. Coliforms were found in 74% of fruit samples, and were internalized in the cores of 40% of fruit tested. Yeasts and molds were internalized in 96.7% of samples and aerobic bacteria in 89.6%. Generic E. coli was not found to be internalized. Total aerobic counts and total coliforms were higher in dropped and damaged fruit (P<0.05) and in orchards associated with fecal contamination or proximity to pastures (P<0.05). Findings suggest that dropped and/or damaged fruit should not be included in fruit designated for the production of unpasteurized juice. Further research is necessary to evaluate the risks associated with proximity to pasture land over an entire growing season.