Variable agronomic practices, cultivar, strain source and initial contamination dose differentially affect survival of Escherichia coli on spinach

Gutiérrez-Rodríguez, Eduardo; Gundersen, A.; Sbodio, Adrian; Suslow, Trevor

doi:10.1111/j.1365-2672.2011.05184.x

Cited by 53 publications

(38 citation statements)

References 32 publications

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“…However, this variable dropped during multivariable modeling where we also considered weather (precipitation over the past month before sampling). This is in agreement with the study by Gutiérrez-Rodríguez et al (45), which reported water availability as the dominant factor in survival of E. coli in a field trial; water availability depends on irrigation, which in turn depends on the local weather (precipitation) providing the rationale for the link between spinach contamination probability and weather. Overall, these results suggest that the time since planting of spinach is a useful predictor of the probability of spinach contamination, albeit its predictive ability compared to those of other considered risk factors (e.g., precipitation) seems lower.…”

Section: Discussionsupporting

confidence: 82%

Multifactorial Effects of Ambient Temperature, Precipitation, Farm Management, and Environmental Factors Determine the Level of Generic Escherichia coli Contamination on Preharvested Spinach

Park

Navratil

Gregory³

et al. 2015

Appl Environ Microbiol

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A repeated cross-sectional study was conducted to identify farm management, environment, weather, and landscape factors that predict the count of generic Escherichia coli on spinach at the preharvest level. E. coli was enumerated for 955 spinach samples collected on 12 farms in Texas and Colorado between 2010 and 2012. Farm management and environmental characteristics were surveyed using a questionnaire. Weather and landscape data were obtained from National Resources Information databases. A two-part mixed-effect negative binomial hurdle model, consisting of a logistic and zero-truncated negative binomial part with farm and date as random effects, was used to identify factors affecting E. coli counts on spinach. Results indicated that the odds of a contamination event (non-zero versus zero counts) vary by state (odds ratio [OR] ‫؍‬ 108.1). Odds of contamination decreased with implementation of hygiene practices (OR ‫؍‬ 0.06) and increased with an increasing average precipitation amount (mm) in the past 29 days (OR ‫؍‬ 3.5) and the application of manure (OR ‫؍‬ 52.2). On contaminated spinach, E. coli counts increased with the average precipitation amount over the past 29 days. The relationship between E. coli count and the average maximum daily temperature over the 9 days prior to sampling followed a quadratic function with the highest bacterial count at around 24°C. These findings indicate that the odds of a contamination event in spinach are determined by farm management, environment, and weather factors. However, once the contamination event has occurred, the count of E. coli on spinach is determined by weather only. Foodborne disease outbreaks associated with produce impose a considerable public health burden (1). Among different produce commodities, leafy green vegetables have been identified as a group of high concern from a microbiological safety perspective due to their being implicated in multiple outbreaks of foodborne disease with high numbers of illnesses worldwide (2). Indeed, leafy green vegetables are commonly grown in open farm fields, where they may be exposed to microbial contamination from soil, manure fertilizer, irrigation water, and intrusions of wild or domestic animals, and they are likely to be consumed fresh or minimally processed. Enteric foodborne pathogens, such as Salmonella and Escherichia coli O157:H7, have been the main causative agents responsible for foodborne outbreaks associated with leafy green vegetables in the United States (3). These pathogens are spread in the environment through feces of infected animals and humans (4). While contamination of leafy greens with these foodborne pathogens has major consequences (2), fortunately it occurs at a low frequency (5, 6). The low frequency and heterogeneous distribution of these pathogens in the produce field make their detection difficult, costly, and time-consuming. Instead indicator organisms are routinely used by the industry, environmental agencies, and public health organizations to verify effective implementation of good ag...

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Section: Discussionsupporting

confidence: 82%

Multifactorial Effects of Ambient Temperature, Precipitation, Farm Management, and Environmental Factors Determine the Level of Generic Escherichia coli Contamination on Preharvested Spinach

Park

Navratil

Gregory³

et al. 2015

Appl Environ Microbiol

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“…Season-to-season variability in the susceptibility of crops to colonization by Salmonella and enterohemorrhagic E. coli pre-and post-harvest have been previously reported (Gutierrez-Rodriguez et al, 2012;. Salmonella proliferation was the highest in fruits harvested in Spring 2011 and Fall 2012 (harvests A and D, Fig.…”

Section: Seasonal Variability and Susceptibility Of Tomatoes To Infecmentioning

confidence: 86%

Effects of nitrogen and potassium fertilization on the susceptibility of tomatoes to post-harvest proliferation of Salmonella enterica

Marvasi¹,

George²,

Giurcanu³

et al. 2014

Food Microbiology

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a b s t r a c tFresh fruits and vegetables are increasingly recognized as vehicles of salmonellosis. Pre-and post-harvest environmental conditions, and physiological, and genetic factors are thought to contribute to the ability of human pathogens to persist in the production environment, attach to, colonize and proliferate in and on raw produce. How field production conditions affect the post-harvest food safety outcomes is not entirely understood. This study tested how varying nitrogen and potassium fertilization levels affected the "susceptibility" of tomatoes to Salmonella infections following the harvest of fruits. Two tomato varieties grown over three seasons under high, medium, and low levels of nitrogen and potassium fertilization in two locations were inoculated with seven strains of Salmonella. Even though the main effects of nitrogen and potassium fertilization on the susceptibility of tomatoes to infections with Salmonella enterica were not statistically significant overall, differences in nitrogen concentrations in plant tissues correlated with the susceptibility of partially ripe tomatoes (cv. Solar Fire) to Salmonella. Tomato maturity and the season in which tomatoes were produced had the strongest effect on the ability of Salmonella to multiply in tomatoes. Tomato phenolics, accumulation of which is known to correlate with rates of the N fertilization, did not inhibit growth of Salmonella in vitro.

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“…While the occurrence of the pathogen in leafy greens on that same sample date was relatively low, subsequent dissemination of high levels of E. coli O157:H7 from the feedlot surface to the plots may have increased the contamination of leafy greens that were sampled on the later dates. Numerous studies have evaluated the risks associated with preharvest contamination of leafy vegetables and have found that E. coli O157:H7 can persist on spinach and lettuce for days up to weeks (31)(32)(33)(34)(35)(36)(37)(38). Both growth chamber and field studies indicate that after inoculation onto leafy greens to mimic a contamination event, populations of E. coli O157:H7 initially decrease rapidly, followed by a more gradual rate of decline of remaining cells.…”

Section: Resultsmentioning

confidence: 99%

Effect of Proximity to a Cattle Feedlot on Escherichia coli O157:H7 Contamination of Leafy Greens and Evaluation of the Potential for Airborne Transmission

Berry

Wells

Bono

et al. 2015

Appl Environ Microbiol

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cThe impact of proximity to a beef cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens was examined. In each of 2 years, leafy greens were planted in nine plots located 60, 120, and 180 m from a cattle feedlot (3 plots at each distance). Leafy greens (270) and feedlot manure samples (100) were collected six different times from June to September in each year. Both E. coli O157:H7 and total E. coli bacteria were recovered from leafy greens at all plot distances. E. coli O157:H7 was recovered from 3.5% of leafy green samples per plot at 60 m, which was higher (P < 0.05) than the 1.8% of positive samples per plot at 180 m, indicating a decrease in contamination as distance from the feedlot was increased. Although E. coli O157:H7 was not recovered from air samples at any distance, total E. coli was recovered from air samples at the feedlot edge and all plot distances, indicating that airborne transport of the pathogen can occur. Results suggest that risk for airborne transport of E. coli O157:H7 from cattle production is increased when cattle pen surfaces are very dry and when this situation is combined with cattle management or cattle behaviors that generate airborne dust. Current leafy green field distance guidelines of 120 m (400 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations. Additional research is needed to determine safe set-back distances between cattle feedlots and crop production that will reduce fresh produce contamination.T he consumption of fresh produce increasingly has been linked to human food-borne disease (1-4). In particular, leafy vegetables, such as spinach and lettuce, have become significant vehicles for the transmission of food-borne pathogens. Produce-associated outbreak surveillance data from the Centers for Disease Control and Prevention (CDC) for the period from 2000 to 2009 showed that among produce commodities, leafy greens were the most frequently linked to outbreaks (5). An analysis of published reports of U.S. fresh produce-associated outbreaks with an attribution risk ranking tool categorized the combination of leafy greens and Escherichia coli O157:H7 with the highest risk ranking score, followed by Salmonella enterica in tomatoes ranking second and S. enterica in leafy greens ranking third (6). For all U.S. foodborne disease outbreaks caused by Shiga toxin-producing E. coli (STEC) in the period of 1998 to 2008, leafy vegetables were the second most common implicated commodity, following beef (2). In addition, spinach, lettuce, and cilantro were commodities most associated with the recovery of STEC in produce market basket surveys conducted within the USDA Agricultural Marketing Service Microbiological Data Program from 2002 to 2012 (7). Leafy greens typically are consumed raw, so protecting these products from microbial contamination in the preharvest environment is critical to reducing the risk for food-borne illness. Potential sources of pathogens for preharvest produ...

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Variable agronomic practices, cultivar, strain source and initial contamination dose differentially affect survival of Escherichia coli on spinach

Cited by 53 publications

References 32 publications

Multifactorial Effects of Ambient Temperature, Precipitation, Farm Management, and Environmental Factors Determine the Level of Generic Escherichia coli Contamination on Preharvested Spinach

Multifactorial Effects of Ambient Temperature, Precipitation, Farm Management, and Environmental Factors Determine the Level of Generic Escherichia coli Contamination on Preharvested Spinach

Effects of nitrogen and potassium fertilization on the susceptibility of tomatoes to post-harvest proliferation of Salmonella enterica

Effect of Proximity to a Cattle Feedlot on Escherichia coli O157:H7 Contamination of Leafy Greens and Evaluation of the Potential for Airborne Transmission

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