Pre-harvest internalization and surface survival of Salmonella and Escherichia coli O157:H7 sprayed onto different lettuce cultivars under field and growth chamber conditions

Erickson, Marilyn C.; Liao, Jye-Yin; Payton, Alison S.; Cook, Peter W.; Bakker, Henk C. den; Bautista, Jesus; Pérez, Juan Carlos Díaz

doi:10.1016/j.ijfoodmicro.2018.12.001

Cited by 21 publications

(19 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance, a study conducted by McKellar et al ( 36 ), which fit log-linear, Cerf, and Weibull regression models to E. coli O157:H7 die-off data from several different experimental trials, found that the biphasic models (i.e., Cerf and Weibull) best fit the data in most cases, with an initial period of rapid decline followed by a period of tailing. Similar patterns were also seen in several other studies ( 25 , 28 , 31 , 37 , 38 , 40 , 46 , 47 ). Brouwer et al ( 48 ), summarized possible mechanisms of this biphasic pattern, which include heterogeneity in the hardiness of the inoculum population, hardening off (i.e., differential gene expression following exposure to harsh environmental conditions), cells entering the viable but not culturable state, and the effect of cell density.…”

Section: Discussionsupporting

confidence: 90%

“…Additionally, the produce plots in 6 out of the 11 trials did not follow the same die-off pattern (i.e., some of the plots followed a segmented log-linear pattern, and some of the plots followed a log-linear die-off pattern). Previous studies have also indicated that a log-linear die-off pattern is not appropriate for foodborne pathogens, indicator organisms, and surrogates on in-field produce ( 25 – 28 , 31 , 36 – 38 , 40 , 45 , 46 ). For instance, a study conducted by McKellar et al ( 36 ), which fit log-linear, Cerf, and Weibull regression models to E. coli O157:H7 die-off data from several different experimental trials, found that the biphasic models (i.e., Cerf and Weibull) best fit the data in most cases, with an initial period of rapid decline followed by a period of tailing.…”

Section: Discussionmentioning

confidence: 99%

“…While no studies looked at the difference in die-off or survival of these two microorganisms or produce types during the initial decay period (i.e., segment 1), several have assessed the overall survival of these organisms on these produce varieties. For instance, Erikson et al ( 46 ) showed that Salmonella had better survival than E. coli O157:H7 under growth chamber and field conditions. Lopez-Velasco et al ( 35 ), also saw better survival of Salmonella than of E. coli on a variety of lettuce cultivars.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Weather on the Die-Off of Escherichia coli and Attenuated Salmonella enterica Serovar Typhimurium on Preharvest Leafy Greens following Irrigation with Contaminated Water

Belias

Sbodio

Truchado

et al. 2020

Appl Environ Microbiol

View full text Add to dashboard Cite

The Food Safety Modernization Act (FSMA) includes a time-to-harvest interval following the application of non-compliant water to pre-harvest produce to allow for microbial die-off. However, additional scientific evidence is needed to support this rule. This study aimed to determine the impact of weather on the die-off rate of E. coli and Salmonella on spinach and lettuce under field conditions. Standardized, replicated field trials were conducted in California, New York, and Spain over two years. Baby spinach and lettuce were grown and inoculated with a ∼104 CFU/mL cocktail of E. coli and attenuated Salmonella. Leaf samples were collected at 7 timepoints (0-96h) following inoculation; E. coli and Salmonella were enumerated. The associations of die-off with study design factors (location, produce type, and bacteria) and weather were assessed using log-linear and biphasic segmented log-linear regression. A segmented log-linear model best fit die-off on inoculated leaves in most cases, with a greater variation in the segment 1 die-off rate across trials [-0.46 (95% confidence interval (95% CI): -0.52, -0.41) to -6.99 (95% CI: -7.38, -6.59) log10 die-off/day] compared to the segment 2 die-off rate [0.28 (95% CI: -0.20, 0.77) to -1.00 (95% CI: -1.16, -0.85) log10 die-off/day]. A lower relative humidity was associated with a faster segment 1 die-off and an earlier breakpoint (the time when segment 1 die-off rate switches to the segment 2 rate). Relative humidity was also found to be associated with whether die-off would comply with FSMA's specified die-off rate of -0.5 log10 die-off/day. Importance The log-linear die-off rate proposed by FSMA is not always appropriate, as the die-off of foodborne bacterial pathogens and specified agricultural water quality indicator organisms appear to commonly follow a biphasic die-off pattern with an initial rapid decline followed by a period of tailing. While we observed substantial variation in the net culturable population levels of Salmonella and E. coli at each time point, die-off rate and FSMA compliance (i.e., at least a 2 log10 die-off over 4 days) appear to be impacted by produce type, bacteria, and weather; die-off on lettuce tended to be faster than that on spinach, die-off of E. coli tended to be faster than that of attenuated Salmonella, and die-off tended to become faster as relative humidity decreased. As such, the use of a single die-off rate for estimating time-to-harvest intervals across different weather conditions, produce types, and bacteria should be revised.

show abstract

Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Weather on the Die-Off of Escherichia coli and Attenuated Salmonella enterica Serovar Typhimurium on Preharvest Leafy Greens following Irrigation with Contaminated Water

Belias

Sbodio

Truchado

et al. 2020

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…In addition, leaf surfaces harbored microbiota communities that were well-adapted to the nutrient-scarce environment, and the competition of microbiota to the invading human pathogens on the leaves could affect the persistence of these pathogens (Monier and Lindow, 2004;Poza-Carrion et al, 2013). Leaf structural morphology of different cultivars of fresh produce have played an important role in the fate of enteric pathogens residing in lettuce foliage (Lopez-Velasco et al, 2015;Van der Linden et al, 2016;Erickson et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Persistence of Escherichia coli O157:H12 and Escherichia coli K12 as Non-pathogenic Surrogates for O157:H7 on Lettuce Cultivars Irrigated With Secondary-Treated Wastewater and Roof-Collected Rain Water in the Field

Yin

Gupta

Chen

et al. 2020

Front. Sustain. Food Syst.

View full text Add to dashboard Cite

Treated wastewater (TW) and roof-collected rain water (RW) that meet the required microbial quality as per Food Safety Modernization Act (FSMA) regulation may serve as alternative irrigation water sources to decrease the pressure on the current water scarcity. Alternative water sources may have different water characteristics that influence the survival and transfer of microorganisms to the irrigated produce. Further, these water sources may contain pathogenic bacteria such as Shiga-toxigenic Escherichia coli. To evaluate the risk associated with TW and RW irrigation on the fresh produce safety, the effect of TW and RW irrigation on the transfer of two non-pathogenic E. coli strains as surrogates for E. coli O157:H7 to different lettuce cultivars grown in the field was investigated. Lettuce cultivars “Annapolis,” “Celinet,” and “Coastline” were grown in the field at the Fulton farm (Chambersburg, PA). Approximately 10 days before harvest, lettuce plants were spray-irrigated with groundwater (GW), TW, or RW containing 6 log CFU ml−1 of a mixture of nalidixic acid-resistant E. coli O157:H12 and chloramphenicol-resistant E. coli K12 in fecal slurry as non-pathogenic surrogates for E. coli O157:H7. On 0, 1, 3, 7, and 10 days post-irrigation, four replicate lettuce leaf samples (30 g per sample) from each group were collected and pummeled in 120 ml of buffered peptone water for 2 min, followed by spiral plating on MacConkey agars with antibiotics. Results showed that the recovery of E. coli O157:H12 was significantly greater than the populations of E. coli K12 recovered from the irrigated lettuce regardless of the water sources and the lettuce cultivars. The TW irrigation resulted in the lowest recovery of the E. coli surrogates on the lettuce compared to the populations of these bacteria recovered from the lettuce with RW and GW irrigation on day 0. The difference in leaf characteristics of lettuce cultivars significantly influenced the recovery of these surrogates on lettuce leaves. Populations of E. coli O157:H12 recovered from the RW-irrigated “Annapolis” lettuce were significantly lower than the recovery of this bacterium from the “Celinet” and “Coastline” lettuce (P < 0.05). Overall, the recovery of specific E. coli surrogates from the RW and TW irrigated lettuce was comparable to the lettuce with the GW irrigation, where GW served as a baseline water source. E. coli O157:H12 could be a more suitable surrogate compared to E. coli K12 because it is an environmental watershed isolate. The findings of this study provide critical information in risk assessment evaluation of RW and TW irrigation on lettuce in Mid-Atlantic area.

show abstract

“…Meanwhile, although not based on a hydroponic cultivation system, Erickson et al [89] investigated the ability of Salmonella to internalize in seven cultivars of leafy greens and one cultivar of Romaine lettuce. The authors spray-inoculated the foliage of three-week old transplants with green fluorescent protein (GFP)-labeled Salmonella (Enteritidis and Newport) and evaluated internalization at 1 and 24 h post-inoculation (p.i.).…”

Section: Plant Cultivar Selectionmentioning

confidence: 99%

Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation

2019

View full text Add to dashboard Cite

Controlled environment agriculture (CEA) is a growing industry for the production of leafy vegetables and fresh produce in general. Moreover, CEA is a potentially desirable alternative production system, as well as a risk management solution for the food safety challenges within the fresh produce industry. Here, we will focus on hydroponic leafy vegetable production (including lettuce, spinach, microgreens, and herbs), which can be categorized into six types: (1) nutrient film technique (NFT), (2) deep water raft culture (DWC), (3) flood and drain, (4) continuous drip systems, (5) the wick method, and (6) aeroponics. The first five are the most commonly used in the production of leafy vegetables. Each of these systems may confer different risks and advantages in the production of leafy vegetables. This review aims to (i) address the differences in current hydroponic system designs with respect to human pathogen internalization risk, and (ii) identify the preventive control points for reducing risks related to pathogen contamination in leafy greens and related fresh produce products.

show abstract

Pre-harvest internalization and surface survival of Salmonella and Escherichia coli O157:H7 sprayed onto different lettuce cultivars under field and growth chamber conditions

Cited by 21 publications

References 35 publications

Effect of Weather on the Die-Off of Escherichia coli and Attenuated Salmonella enterica Serovar Typhimurium on Preharvest Leafy Greens following Irrigation with Contaminated Water

Effect of Weather on the Die-Off of Escherichia coli and Attenuated Salmonella enterica Serovar Typhimurium on Preharvest Leafy Greens following Irrigation with Contaminated Water

Persistence of Escherichia coli O157:H12 and Escherichia coli K12 as Non-pathogenic Surrogates for O157:H7 on Lettuce Cultivars Irrigated With Secondary-Treated Wastewater and Roof-Collected Rain Water in the Field

Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation

Contact Info

Product

Resources

About