Summer meeting 2007 the problems with fresh produce: an overview

Abstract

Summary In Fall 2006, four separate outbreaks of foodborne illness associated with the consumption of fresh produce occurred in the United States. In follow‐up investigations, spinach, lettuce, and tomatoes were identified as the vehicles of illness. Epidemiologic investigations subsequently focused on finding the specific growing regions using traceback records. While the areas most likely involved in the outbreaks have been identified, the specific mode of contamination remains unconfirmed. Suspected risk factors in these cases include: proximity of irrigation wells and surface waterways exposed to faeces from cattle and wildlife; exposure in fields to wild animals and their waste materials; and improperly composted animal manure used as fertilizer. Difficulty in deciphering these and other on‐farm routes of contamination is due to the sporadic nature of these events. Hence, evidence to support these contamination modes is based largely on experimental studies in the laboratory and field. Still at issue is the relevance of internalization of pathogens, whether this occurs through the roots and plant vascular tissues of vegetables and fruits or through plant surfaces into cracks and crevices. Potential for these events, conditions under which the events occur, and pathogen survival following these events, are questions that still need to be answered. Answers to these questions will ultimately affect the type of interventions needed for application postharvest. Currently, many chemical and biological interventions can reduce surface pathogens and minimize cross‐contamination, however, they are largely ineffective on internalized pathogens. In the event internalization is a significant route of contamination in the field, physical interventions (irradiation and high pressure) may be needed to minimize risk. Ultimately, risk assessment studies will be useful tools in developing risk management strategies for the produce industry.

Comanaging fresh produce for nature conservation and food safety

“…Fresh produce is now the leading cause of foodborne illnesses (46%) and hospitalizations (38%) in the United States (1), up from <1% of outbreaks in the 1970s (2). As a result, system-wide reforms have swept through produce supply chains (3,4).…”

“…Two groups of pathogens, enterohemorrhagic E. coli (EHEC) and Salmonella enterica, are largely responsible for the perceived conflict between food safety and nature conservation, as well as for the majority of bacterial outbreaks in fresh produce (2). Both pathogens are carried by domestic animals (e.g., cattle) and wildlife; however, whereas S. enterica is readily isolated from many wildlife hosts (10,11), EHEC is generally more prevalent in cattle than in wildlife.…”

Escherichia coli Common Pilus (ECP) Targets Arabinosyl Residues in Plant Cell Walls to Mediate Adhesion to Fresh Produce Plants

“…Several bacterial pathogens have been involved in different foodborne outbreaks, including pathogenic Escherichia coli and Salmonella enterica (5)(6)(7)(8)(9)(10).…”

Investigation of the hygienic safety of aromatic plants cultivated in soil contaminated with Listeria monocytogenes

“…The transfer of this food-borne pathogen on the surface of vegetable leaves may occur in several ways and the contact with soil may play a defining role in this process, since L. monocytogenes is generally found in soil (Welshimer & Donker-Voet, 1971). Many food-borne pathogens are transmitted from soil to fresh vegetables during the pre-harvest period, especially when the cultivation soil had been amended with manure-containing fertilizers, sewage sludge or the irrigation occurred with contaminated water (alGhazali & al-Azawi, 1990;Beuchat, 1996;Doyle & Erickson, 2008). The recent events concerning the contamination of different vegetable products by E. coli O124, that caused the death of several persons of different ages in Northern Europe (Moulson, 2011), have highlighted the importance of the safety characteristics of vegetables to be eaten raw, especially when cultivated under organic regimes which commonly employ manures as fertilizers.…”