Population dynamics of Escherichia coli inoculated by irrigation into the phyllosphere of spinach grown under commercial production conditions

Wood, JD; Bezanson, G. S.; Gordon, Robert J.; Jamieson, Rob

doi:10.1016/j.ijfoodmicro.2010.08.022

Cited by 62 publications

(44 citation statements)

References 30 publications

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“…The concentrations of E. coli on produce following harvest can be expected to reduce with time, and as a result of environmental conditions. For example, a field trial in Nova Scotia, Canada, to determine the survival of E. coli on market-ready spinach after spray inoculation showed a reduction of 3-5 log units after 72 h [198]. The reduction of E. coli with time across domains was not shown in this study, especially during the rainy season and could suggest that post-harvest handling and practices did influence contamination levels at markets and kitchens.…”

Section: Wastewater Use and Produce Qualitycontrasting

confidence: 60%

Wastewater use in urban agriculture: an exposure and risk assessment in Accra, Ghana

Agyei

Ensink

2016

Jnl Sci Tech

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In order to minimize the health risks to agricultural workers, and consumers of wastewater irrigated produce, the World Health Organisation has developed guidelines for the safe use of wastewater in agriculture. This study sought to test the appropriateness of the current Quantitative Microbial Risk Assessment model and the multiple-barrier approach advocated by the WHO guidelines.Over a one year period, over 500 produce and ready-to-eat salad samples were collected from fields, markets, and kitchens in Accra, Ghana, and over 300 soil and irrigation water samples were collected. All samples were analysed for E. coli, human adenovirus and norovirus using standard microbiological procedures. In addition, almost 700 participants including farmers, food vendors, and consumers were interviewed and observed to assess critical exposures associated with the transmission of faecal pathogens.The results showed that irrigation water was significantly more contaminated than farm soil, though exposure to soil was found to pose the key risk to farmers due to hand-to-mouth events. Over 80% of produce samples were found contaminated with E. coli, with street food salad being the most contaminated (4.23 Log E. coli/g), and that consumption of salads did not meet health standards. Risk factors identified for produce contamination included farm soil contamination, wastewater use for irrigation, poor hygiene, and operating with a hygiene permit. Awareness of the source of irrigation water was low, but despite the high awareness of health risk, consumers did not prioritize health indicators when buying produce from vendors. Similarly, farmers' awareness of health risk did not influence their adoption of safer farm practices. The study recommends the promotion of interventions that would result in more direct benefits to producers and vendors, together with hygiene education and inspection, hygiene certification and enforcement of food safety byelaws in order to increase the uptake of the multi-barrier approach. 4PhD related documents 2014:

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Section: Wastewater Use and Produce Qualitycontrasting

confidence: 60%

Wastewater use in urban agriculture: an exposure and risk assessment in Accra, Ghana

Agyei

Ensink

2016

Jnl Sci Tech

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“…These studies indicate that some foodborne pathogens have the ability to survive in secondary habitats and have a sustained presence in the agricultural environment (9). In particular, E. coli O157:H7 has the capacity to survive the harsh conditions imparted by UV irradiation and low nutrient and water availability conditions and appears to adequately compete with epiphytes, commensals, and phytobacteria in plant phyllospheres and rhizospheres (64,67).…”

mentioning

confidence: 99%

Transcriptional Responses of Escherichia coli K-12 and O157:H7 Associated with Lettuce Leaves

Fink

Black

Hou

et al. 2012

Appl Environ Microbiol

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An increasing number of outbreaks of gastroenteritis recently caused by Escherichia coli O157:H7 have been linked to the consumption of leafy green vegetables. Although it is known that E. coli survives and grows in the phyllosphere of lettuce plants, the molecular mechanisms by which this bacterium associates with plants are largely unknown. The goal of this study was to identify E. coli genes relevant to its interaction, survival, or attachment to lettuce leaf surfaces, comparing E. coli K-12, a model system, and E. coli O157:H7, a pathogen associated with a large number of outbreaks. Using microarrays, we found that upon interaction with intact leaves, 10.1% and 8.7% of the 3,798 shared genes were differentially expressed in K-12 and O157:H7, respectively, whereas 3.1% changed transcript levels in both. The largest group of genes downregulated consisted of those involved in energy metabolism, including tnaA (33-fold change), encoding a tryptophanase that converts tryptophan into indole. Genes involved in biofilm modulation (bhsA and ybiM) and curli production (csgA and csgB) were significantly upregulated in E. coli K-12 and O157:H7. Both csgA and bhsA (ycfR) mutants were impaired in the long-term colonization of the leaf surface, but only csgA mutants had diminished ability in short-term attachment experiments. Our data suggested that the interaction of E. coli K-12 and O157:H7 with undamaged lettuce leaves likely is initiated via attachment to the leaf surface using curli fibers, a downward shift in their metabolism, and the suppression of biofilm formation.

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“…The bacteriological analysis of the plant and fruit samples included determination of E. coli, faecal coliforms, and total heterotrophic counts (THCs). These analyses were conducted by the plate- count method on tryptone bile X-glucuronide agar, E. coli agar, and tryptone soya agar, respectively (Allen et al, 2004;Wood et al, 2010). Moreover, the tomato plant and fruit samples were also analysed for Salmonella spp.…”

Section: Water and Tomato Fruit Analysismentioning

confidence: 99%

Effects of treated agro-industrial wastewater irrigation on tomato processing quality

et al. 2015

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This study was designed to determine the qualitative and microbiological impact of two different sources of irrigation water on tomato fruit: groundwater (GW), as the control, and treated agro-industrial wastewater (SW). The mean tomato fruit quality parameters of dry matter, weight, diameter, colour index, pH, soluble solids content, titratable acidity, Ca 2+ and Na + content were not significantly affected by the different water treatments. Conversely, NO3 -contents was significantly higher with GW use, than with SW (2.21 vs 1.62 mg 100 g -1 , respectively; P≤0.05). The microbial quality of the tomato fruit was not significantly different across the GW and SW treatments, with no Salmonella spp. isolated from any of the fruit, and the faecal indicators always below 10 CFU g -1 . These data show that agro-industrial treated wastewater can be used for irrigation for industrial tomato production once the long-term effects on the agroecosystem have been defined.

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Population dynamics of Escherichia coli inoculated by irrigation into the phyllosphere of spinach grown under commercial production conditions

Cited by 62 publications

References 30 publications

Wastewater use in urban agriculture: an exposure and risk assessment in Accra, Ghana

Wastewater use in urban agriculture: an exposure and risk assessment in Accra, Ghana

Transcriptional Responses of Escherichia coli K-12 and O157:H7 Associated with Lettuce Leaves

Effects of treated agro-industrial wastewater irrigation on tomato processing quality

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