Risk Factors for Microbial Contamination in Fruits and Vegetables at the Preharvest Level: A Systematic Review

Abstract

The objective of this study was to perform a systematic review of risk factors for contamination of fruits and vegetables with Listeria monocytogenes, Salmonella, and Escherichia coli O157:H7 at the preharvest level. Relevant studies were identified by searching six electronic databases: MEDLINE, EMBASE, CAB Abstracts, AGRIS, AGRICOLA, and FSTA, using the following thesaurus terms: L. monocytogenes, Salmonella, E. coli O157 AND fruit, vegetable. All search terms were exploded to find all related subheadings. To be eligible, studies had to be prospective controlled trials or observational studies at the preharvest level and had to show clear and sufficient information on the process in which the produce was contaminated. Of the 3,463 citations identified, 68 studies fulfilled the eligibility criteria. Most of these studies were on leafy greens and tomatoes. Six studies assessed produce contamination with respect to animal host-related risk factors, and 20 studies assessed contamination with respect to pathogen characteristics. Sixty-two studies assessed the association between produce contamination and factors related to produce, water, and soil, as well as local ecological conditions of the production location. While evaluations of many risk factors for preharvest-level produce contamination have been reported, the quality assessment of the reviewed studies confirmed the existence of solid evidence for only some of them, including growing produce on clay-type soil, the application of contaminated or non-pH-stabilized manure, and the use of spray irrigation with contaminated water, with a particular risk of contamination on the lower leaf surface. In conclusion, synthesis of the reviewed studies suggests that reducing microbial contamination of irrigation water and soil are the most effective targets for the prevention and control of produce contamination. Furthermore, this review provides an inventory of the evaluated risk factors, including those requiring more research.

Microbiological Quality of Organic and Conventional Leafy Vegetables

“…The control of this source of contamination has been indicated as one of the most promising targets to reduce microbial contamination [34]. During this study, technical visits were made to both production areas (conventional and organic cultivation).…”

Microbiological safety of organic and conventional foods

“…Use of organic fertilizers according to good agricultural practice (GAP) does not increase the rate of contamination of fresh produce by enteric pathogens (Alsanius, 2014) or Escherichia coli (literature data summarized by Smith-Spangler et al, 2012). As learned from outbreaks and field studies, the main risk factors are use of irrigation water that had been contaminated by human or livestock excreta (Park et al, 2012), and handling of produce by carriers of pathogens, but not the farming system (Marine et al, 2015). Some outbreaks have been reported in which leafy vegetables were shown or suspected to be involved (CDC, 2016).…”

Occurrence of Escherichia coli harbouring stx genes in popiah, a Malaysian street food

“…The water used could be a source of contamination of E. coli, if it is poorly treated. In addition, raw vegetables such as bean sprouts may represent an important source of risk for human health because they can become carriers of pathogenic micro-organisms (Harris et al, 2003;Park et al, 2012). Indeed, their complex surface and porosity, unfortunately facilitate the pathogen attachment which leads to their survival SHORT COMMUNICATION eISSN: 2550-2166 (Report of the Scientific Committee on Food, 2002;Said, 2012).…”

“…It is mostly made with a filling of shredded raw vegetables, and various studies has shown that raw vegetables represent an important source of risk for human health because they are carriers of pathogenic micro-organisms (Harris et al, 2003;Park et al, 2012). The Enteroaggregative E. coli (EAEC), Enteropathogenic E. coli (EPEC), Enterotoxigenic E. coli (ETEC), Enteroinvasive E. coli (EIEC) and non-O157 Shiga toxin-producing E. coli are the important causative agents of diarrhea in developed countries (Nataro and Kaper, 1998;Nataro, 2004;Estrada-Garcia et al, 2005).…”