Salmonella and produce: Survival in the plant environment and implications in food safety

Fatica, Marianne K.; Schneider, Keith R.

doi:10.4161/viru.2.6.17880

Cited by 90 publications

(64 citation statements)

References 57 publications

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“…A common mechanism of host-to-host transmission is shedding of bacteria in the feces of pathogen-bearing farm animals (7)(8)(9). Indeed, contact with animal feces is a risk factor for sporadic infection with EHEC (10).…”

mentioning

confidence: 99%

Biofilm Formation Protects Escherichia coli against Killing by Caenorhabditis elegans and Myxococcus xanthus

DePas

Syed

Sifuentes

et al. 2014

Appl Environ Microbiol

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cEnteric bacteria, such as Escherichia coli, are exposed to a variety of stresses in the nonhost environment. The development of biofilms provides E. coli with resistance to environmental insults, such as desiccation and bleach. We found that biofilm formation, specifically production of the matrix components curli and cellulose, protected E. coli against killing by the soil-dwelling nematode Caenorhabditis elegans and the predatory bacterium Myxococcus xanthus. Additionally, matrix-encased bacteria at the air-biofilm interface exhibited ϳ40-fold-increased survival after C. elegans and M. xanthus killing compared to the nonmatrix-encased cells that populate the interior of the biofilm. To determine if nonhost Enterobacteriaceae reservoirs supported biofilm formation, we grew E. coli on media composed of pig dung or commonly contaminated foods, such as beef, chicken, and spinach. Each of these medium types provided a nutritional environment that supported matrix production and biofilm formation. Altogether, we showed that common, nonhost reservoirs of E. coli supported the formation of biofilms that subsequently protected E. coli against predation.

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mentioning

confidence: 99%

Biofilm Formation Protects Escherichia coli against Killing by Caenorhabditis elegans and Myxococcus xanthus

DePas

Syed

Sifuentes

et al. 2014

Appl Environ Microbiol

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“…This approach also mimics certain aspects of the cross-contamination process in which contaminated water may be sprayed on fresh produce during vacuum cooling. Sanitation of the processing water used during cooling and washing has been a subject of significant concern in the fresh produce-processing industry (19)(20)(21). In order to determine the average load sprayed onto the leaf disks, leaf disks with surface-inoculated E. coli O157:H7 GFPlux were prepared and vortexed in 5 ml of 1ϫ PBS buffer for 10 min immediately following inoculation.…”

Section: Methodsmentioning

confidence: 99%

Influence of Vacuum Cooling on Escherichia coli O157:H7 Infiltration in Fresh Leafy Greens via a Multiphoton-Imaging Approach

Vonasek

Nitin

2016

Appl Environ Microbiol

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Microbial pathogen infiltration in fresh leafy greens is a significant food safety risk factor. In various postharvest operations, vacuum cooling is a critical process for maintaining the quality of fresh produce. The overall goal of this study was to evaluate the risk of vacuum cooling-induced infiltration of Escherichia coli O157:H7 into lettuce using multiphoton microscopy. Multiphoton imaging was chosen as the method to locate E. coli O157:H7 within an intact lettuce leaf due to its high spatial resolution, low background fluorescence, and near-infrared (NIR) excitation source compared to those of conventional confocal microscopy. The variables vacuum cooling, surface moisture, and leaf side were evaluated in a three-way factorial study with E. coli O157:H7 on lettuce. A total of 188 image stacks were collected. The images were analyzed for E. coli O157:H7 association with stomata and E. coli O157:H7 infiltration. The quantitative imaging data were statistically analyzed using analysis of variance (ANOVA). The results indicate that the low-moisture condition led to an increased risk of microbial association with stomata (P < 0.05). Additionally, the interaction between vacuum cooling levels and moisture levels led to an increased risk of infiltration (P < 0.05). This study also demonstrates the potential of multiphoton imaging for improving sensitivity and resolution of imaging-based measurements of microbial interactions with intact leaf structures, including infiltration. V acuum cooling is a postharvest-processing operation that preserves the quality of fresh produce by rapidly reducing its temperature. Cooling fresh produce to refrigerated temperatures increases shelf life and product quality by reducing cellular activity (1). The vacuum cooling process cools fresh produce by lowering pressure within a sealed chamber and inducing surface moisture evaporation (2-5). Evaporating the surface moisture reduces the enthalpy in the system by taking energy from the surrounding tissue, thereby reducing the temperature in fresh produce. The product may be sprayed with water during the vacuum cooling process in order to prevent excessive water loss from surface evaporation (4, 5).A recent study suggested that vacuum cooling may increase the risk of microbial infiltration into fresh produce, thereby increasing the risk of food-borne illness from microbial food pathogens (6). Microbial infiltration of pathogens in fresh leafy greens significantly increases the risk of food-borne illness, as the infiltrated microbes cannot be effectively removed or treated utilizing standard sanitation and washing processes (6, 7). Microbial infiltration has been reported in both preharvest and postharvest processing of leafy greens (7,8). During postharvest, microbial infiltration mechanisms are predominantly associated with stomata in intact leaf tissue and in some cases associated with damage to the leaf tissue due to the presence of nutrients from these openings in the plant tissue (6-9). Thus, the reported increase in microbial i...

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“…31,32 Enteric pathogens, including Salmonella spp, may exhibit mechanisms to survive on plants to use them as a transfer medium between the environment and their animal hosts and eventually the animal host sheds the bacterium back into the environment. 4 The bacteria may persist in the plant environment through the formation of biofilms either on or within the plants. Salmonella ser Thompson was visualized on lettuce leaves through episcopic differential interference contrast microscopy coupled with epi-fluorescence to find that the aggregated cells appeared slimy, suggesting the formation of a biofilm on the lettuce.…”

Section: Sources Of Contaminationmentioning

confidence: 99%

“…or through handling during processing, storage and marketing. 4 E. coli O157:H7 has been found in fecal samples of several hosts (horses, birds, dogs, flies) but cattle are the most significant source of contamination. [16][17][18][19] It is evident that such globalization of the fresh vegetable supply may contribute to the introduction and dissemination of hazards from producing regions into other wider geographical areas.…”

Section: Sources Of Contaminationmentioning

confidence: 99%

“…Therefore contamination with pathogens may occur in any step from farm to table. 4,5 Several strategies for controlling the pathogen E. coli O157:H7 are summarized by Chauret 6 such as chemical and heat treatment, irradiation, pulsed electric field (PEF) pasteurization and high pressure processing. These procedures have a wide range of applications for the Food and Water Industry.…”

Section: Sources Of Contaminationmentioning

confidence: 99%

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Ecological attributes of foodborne infections

Skandamis¹,

Nychas²

2011

Virulence

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Salmonella and produce: Survival in the plant environment and implications in food safety

Cited by 90 publications

References 57 publications

Biofilm Formation Protects Escherichia coli against Killing by Caenorhabditis elegans and Myxococcus xanthus

Biofilm Formation Protects Escherichia coli against Killing by Caenorhabditis elegans and Myxococcus xanthus

Influence of Vacuum Cooling on Escherichia coli O157:H7 Infiltration in Fresh Leafy Greens via a Multiphoton-Imaging Approach

Ecological attributes of foodborne infections

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