Fate of Escherichia coli O145 present naturally in bovine slurry applied to vegetables before harvest, after washing and simulated wholesale and retail distribution

Hutchison, M.L., Harrison, D., Heath, J.F. and Monaghan, J.M. (2017) Fate of Escherichia coli O145 present naturally in bovine slurry applied to vegetables before harvest, after washing and simulated wholesale and retail distribution. Journal of Applied Microbiology, 123 (6). pp. 1597-1606.

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Abstract

Aims: To determine the fate of E. coli on vegetables that were processed through commercial wash treatments and stored under simulated retail conditions at 4oC or wholesale at fluctuating ambient temperatures (0-25oC, dependent on season). Methods and Results: Bovine slurry that was naturally contaminated with Escherichia coli O145 was applied without dilution or diluted 1/10 using borehole water to growing potatoes, leeks or carrots. Manure was applied one week prior to harvest to simulate a near-harvest contamination event by manure deposition or an application of contaminated water to simulate a flooding event or irrigation from a contaminated water source. At harvest, crops were contaminated at up to two log cfu/g. Washing transferred E. coli into the water of a flotation tank used for potato washing and did not completely remove all traces of contamination from the crop. Manure contaminated potatoes were observed to contain 0.72 cfu E. coli O145/g after processing and retail storage. Manure-contaminated leeks harboured 0.73 – 1.55 cfu E. coli O145/g after washing and storage. There was no cross contamination when leeks were spray-washed. Washing in an abrasive drum resulted in less than perfect decontamination for manure-contaminated carrots. There were five post-distribution isolations from carrots irrigated with contaminated water 24h prior to harvest. Conclusions: Standard commercial washing and distribution conditions may be insufficient to reliably control human pathogenic E. coli on fresh produce. Significance and Impact: Previous speculation that the cause of a UK foodborne disease outbreak was soil from imperfectly cleaned vegetables is plausible.

Item Type: Article
Keywords: E. coli, fresh produce, irrigation water, livestock manure, zoonotic agent
Divisions: Crop and Environment Sciences (to 31.07.20)
Depositing User: Ms Kath Osborn
Date Deposited: 23 Nov 2017 16:46
Last Modified: 12 Jan 2018 10:56
URI: https://hau.repository.guildhe.ac.uk/id/eprint/17211

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