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Hopper AL, Hudson CL, Klair D, Ding Q, Gao Z, Jha A, Bryan A, Tikekar RV, Coolong T, Dunn LL, Micallef SA. Rain splash-mediated dispersal of Escherichia coli from fecal deposits to field-grown lettuce in the mid- and south Atlantic U.S. regions is affected by mulch type. FRONTIERS IN PLANT SCIENCE 2024; 15:1370495. [PMID: 38567141 PMCID: PMC10985140 DOI: 10.3389/fpls.2024.1370495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 02/29/2024] [Indexed: 04/04/2024]
Abstract
Introduction Wildlife feces can contaminate vegetables when enteric bacteria are released by rain and splashed onto crops. Regulations require growers to identify and not harvest produce that is likely contaminated, but U.S. federal standards do not define dimensions for no-harvest zones. Moreover, mulching, used to retain soil moisture and maximize crop yield may impact rain-mediated bacterial dispersal from feces. Methods To assess Escherichia coli dissemination from a fecal point source to lettuce grown on various mulches, lettuce cv. 'Magenta' was transplanted into raised beds with plastic, biodegradable plastic, straw, or left uncovered at field sites in Maryland and Georgia. Eleven days post-transplant, 10 g of rabbit manure spiked with ~8 log CFU g-1 E. coli were deposited in each bed. One day following natural or simulated rain events, lettuce was sampled along 1.5 m transects on either side of fecal deposits. Lettuce-associated E. coli was semi-quantified with an MPN assay and dependence on fecal age (stale or fresh), lettuce age (baby leaf or mature head), distance from point source, mulch and post-rain days were statistically evaluated. Results Distance (p<0.001), fecal age (p<0.001) and mulch (p<0.01) were factors for E. coli transfer from point source to lettuce. The highest and lowest E. coli estimates were measured from lettuce grown on biodegradable plastic and straw, respectively, with a 2-log MPN difference (p<0.001). Mulch and distance were also significant factors in E. coli recovery 3 days post-rain (both p<0.001), where plastic mulches differed from bare ground and straw (p<0.01). For all treatments, fewer E. coli were retrieved from lettuce at 0.3 m, 3 days post-rain compared to 1 day (p<0.001). Fitting the data to a Weibull Model predicated that a 7-log reduction in E. coli from fecal levels would be achieved at 1.2-1.4 m from the point source on plastic mulches, 0.75 m on bare soil (p<0.05) and 0.43 m on straw (p<0.01). Discussion Straw and bare ground limited rain-mediated E. coli dispersal from feces to lettuce compared to plastic mulches. Fecal age was negatively associated with E. coli dispersal. These findings can inform harvesting recommendations for measures related to animal intrusion in vegetable production areas.
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Affiliation(s)
- Adam L. Hopper
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
| | - Claire L. Hudson
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
| | - Diksha Klair
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
| | - Qiao Ding
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
| | - Zhujun Gao
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, United States
| | - Aprajeeta Jha
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, United States
| | - Austin Bryan
- Department of Food Science and Technology, University of Georgia, Athens, GA, United States
| | - Rohan V. Tikekar
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, United States
| | - Timothy Coolong
- Department of Horticulture, University of Georgia, Athens, GA, United States
| | - Laurel L. Dunn
- Department of Food Science and Technology, University of Georgia, Athens, GA, United States
| | - Shirley A. Micallef
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
- Center for Food Safety and Security Systems, University of Maryland, College Park, MD, United States
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Wu J, Gathman RJ, Quintanilla Portillo J, Gaulke C, Kim M, Stasiewicz MJ. Aggregative Soil Sampling Using Boot Covers Compared to Soil Grabs From Commercial Romaine Fields Shows Similar Indicator Organism and Microbial Community Recoveries. J Food Prot 2023; 86:100177. [PMID: 37805043 DOI: 10.1016/j.jfp.2023.100177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/26/2023] [Accepted: 10/03/2023] [Indexed: 10/09/2023]
Abstract
Aggregative boot cover sampling may be a more representative, practical, and powerful method for preharvest produce soil testing than grab sampling because boot covers aggregate soil from larger areas. Our study tests if boot cover sampling results reflect quality and safety indicator organisms and community diversity of grab sampling. We collected soil samples from commercial romaine lettuce fields spanning 5060 m2 using boot covers (n = 28, m = 1.1 ± 0.4 g; wearing boot covers and walking along the path), composite grabs (n = 28, m = 231 ± 24 g; consisting of 60 grabs of 3-5 g each), and high-resolution grabs (n = 72, m = 56 ± 4 g; taking one sample per stratum). Means and standard deviations of log-transformed aerobic plate counts (APCs) were 7.0 ± 0.3, 7.1 ± 0.2, and 7.3 ± 0.2 log(CFU/g) for boot covers, composite grabs, and high-resolution grabs, respectively. APCs did not show biologically meaningful differences between sample types. Boot covers recovered on average 0.6 log(CFU/g) more total coliforms than both grabs (p < 0.001) where means and standard deviations of log-transformed counts were 3.2 ± 1.0, 2.6 ± 0.6, and 2.6 ± 1.0 log(CFU/g) for boot covers, composite grabs, and high-resolution grabs, respectively. There were no generic E. coli detected in any sample by enumeration methods with LODs of 1.3-2.1 log(CFU/g) for boot covers and 0.5 log(CFU/g) for both grabs. By 16S rRNA sequencing, community species diversity (alpha diversity) was not significantly different within collection methods. While communities differed (p < 0.001) between soil sampling methods (beta diversity), variance in microbial communities was not significantly different. Of the 28 phyla and 297 genera detected, 25 phyla (89%) and 258 genera (87%) were found by all methods. Overall, aggregative boot cover sampling is similar to both grab methods for recovering quality and safety indicator organisms and representative microbiomes. This justifies future work testing aggregative soil sampling for foodborne pathogen detection.
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Affiliation(s)
- Jiaying Wu
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Rachel J Gathman
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jorge Quintanilla Portillo
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Christopher Gaulke
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana Champaign, Urbana, IL 61802, USA; Personalized Nutrition Initiative, University of Illinois at Urbana Champaign, Urbana, IL 61802, USA; Cancer Center at Illinois, University of Illinois at Urbana Champaign, Urbana, IL 61802, USA
| | - Minho Kim
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Matthew J Stasiewicz
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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Weng X, Liu Y, Hu H, Wang M, Huang X. Changes of microbiota level in urinary tract infections: A meta-analysis. Open Med (Wars) 2023; 18:20230702. [PMID: 37251539 PMCID: PMC10224615 DOI: 10.1515/med-2023-0702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 04/02/2023] [Accepted: 04/04/2023] [Indexed: 05/31/2023] Open
Abstract
No consensus has been reached on the dysbiosis signs of microbiota in patients with urinary tract infections (UTIs). This meta-analysis aimed to verify the relationship between microbiota levels and UTIs. PubMed, Web of Science, and Embase databases were retrieved for related articles published from inception until October 20, 2021. The standardized mean difference (SMD) and its related 95% confidence intervals (CIs) of the microbiota diversity and abundance were pooled under a random-effects model. Twelve studies were included in this meta-analysis. The pooled analysis revealed that the microbiota diversity was lower in patients with UTIs than in healthy individuals (SMD = -0.655, 95% CI = -1.290, -0.021, I 2 = 81.0%, P = 0.043). The abundance of specific bacteria was higher in UTI subjects compared with healthy control individuals (SMD = 0.41, 95% CI = 0.07-0.74, P = 0.017), especially in North America patients with UTIs. Similar results were also found in studies with the total sample size being greater than 30. Importantly, Escherichia coli levels were increased in patients with UTI, whereas Lactobacillus levels decreased. E. coli and Lactobacilli have huge prospects as potential microbiota markers in the treatment of UTIs.
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Affiliation(s)
- Xia Weng
- Urology Department, Zhejiang Hospital, Hangzhou310013, Zhejiang Province, China
| | - Yajun Liu
- Neurosurgery Department, Zhejiang Provincial Hospital of Traditional Chinese Medicine, Hangzhou, Zhejiang Province, China
| | - Haiping Hu
- Urology Department, Zhejiang Hospital, Hangzhou310013, Zhejiang Province, China
| | - Meichai Wang
- Urology Department, Zhejiang Hospital, Hangzhou310013, Zhejiang Province, China
| | - Xiaoqin Huang
- Orthopedics Department, Zhejiang Hospital, No. 1229, Gudun Road, Hangzhou 310013, Zhejiang Province, China
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Pires AFA, Ramos TDM, Baron JN, Millner PD, Pagliari PH, Hutchinson M, Haghani V, Aminabadi P, Kenney A, Hashem F, Martínez-López B, Bihn EA, Clements DP, Shade JB, Sciligo AR, Jay-Russell MT. Risk factors associated with the prevalence of Shiga-toxin-producing Escherichia coli in manured soils on certified organic farms in four regions of the USA. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2023. [DOI: 10.3389/fsufs.2023.1125996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023] Open
Abstract
IntroductionBiological soil amendments of animal origin (BSAAO), including untreated amendments are often used to improve soil fertility and are particularly important in organic agriculture. However, application of untreated manure on cropland can potentially introduce foodborne pathogens into the soil and onto produce. Certified organic farms follow the USDA National Organic Program (NOP) standards that stipulate a 90- or 120-day interval between application of untreated manure and crop harvest, depending on whether the edible portion of the crop directly contacts the soil. This time-interval metric is based on environmental factors and does not consider a multitude of factors that might affect the survival of the main pathogens of concern. The objective of this study was to assess predictors for the prevalence of Shiga-toxin-producing Escherichia coli (non-O157 STEC) in soils amended with untreated manure on USDA-NOP certified farms.MethodsA longitudinal, multi-regional study was conducted on 19 farms in four USA regions for two growing seasons (2017–2018). Untreated manure (cattle, horse, and poultry), soil, and irrigation water samples were collected and enrichment cultured for non-O157 STEC. Mixed effects logistic regression models were used to analyze the predictors of non-O157 STEC in the soil up to 180 days post-manure application.Results and discussionResults show that farm management practices (previous use with livestock, presence of animal feces on the field, season of manure application) and soil characteristics (presence of generic E. coli in the soil, soil moisture, sodium) increased the odds of STEC-positive soil samples. Manure application method and snowfall decreased the odds of detecting STEC in the soil. Time-variant predictors (year and sampling day) affected the presence of STEC. This study shows that a single metric, such as the time interval between application of untreated manure and crop harvest, may not be sufficient to reduce the food safety risks from untreated manure, and additional environmental and farm-management practices should also be considered. These findings are of particular importance because they provide multi-regional baseline data relating to current NOP wait-time standards. They can therefore contribute to the development of strategies to reduce pathogen persistence that may contribute to contamination of fresh produce typically eaten raw from NOP-certified farms using untreated manure.
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A Validated Preharvest Sampling Simulation Shows that Sampling Plans with a Larger Number of Randomly Located Samples Perform Better than Typical Sampling Plans in Detecting Representative Point-Source and Widespread Hazards in Leafy Green Fields. Appl Environ Microbiol 2022; 88:e0101522. [PMID: 36377948 PMCID: PMC9746328 DOI: 10.1128/aem.01015-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Commercial leafy greens customers often require a negative preharvest pathogen test, typically by compositing 60 produce sample grabs of 150 to 375 g total mass from lots of various acreages. This study developed a preharvest sampling Monte Carlo simulation, validated it against literature and experimental trials, and used it to suggest improvements to sampling plans. The simulation was validated by outputting six simulated ranges of positive samples that contained the experimental number of positive samples (range, 2 to 139 positives) recovered from six field trials with point source, systematic, and sporadic contamination. We then evaluated the relative performance between simple random, stratified random, or systematic sampling in a 1-acre field to detect point sources of contamination present at 0.3% to 1.7% prevalence. Randomized sampling was optimal because of lower variability in probability of acceptance. Optimized sampling was applied to detect an industry-relevant point source [3 log(CFU/g) over 0.3% of the field] and widespread contamination [-1 to -4 log(CFU/g) over the whole field] by taking 60 to 1,200 sample grabs of 3 g. More samples increased the power of detecting point source contamination, as the median probability of acceptance decreased from 85% with 60 samples to 5% with 1,200 samples. Sampling plans with larger total composite sample mass increased power to detect low-level, widespread contamination, as the median probability of acceptance with -3 log(CFU/g) contamination decreased from 85% with a 150-g total mass to 30% with a 1,200-g total mass. Therefore, preharvest sampling power increases by taking more, smaller samples with randomization, up to the constraints of total grabs and mass feasible or required for a food safety objective. IMPORTANCE This study addresses a need for improved preharvest sampling plans for pathogen detection in leafy green fields by developing and validating a preharvest sampling simulation model, avoiding the expensive task of physical sampling in many fields. Validated preharvest sampling simulations were used to develop guidance for preharvest sampling protocols. Sampling simulations predicted that sampling plans with randomization are less variable in their power to detect low-prevalence point source contamination in a 1-acre field. Collecting larger total sample masses improved the power of sampling plans in detecting widespread contamination in 1-acre fields. Hence, the power of typical sampling plans that collect 150 to 375 g per composite sample can be improved by taking more, randomized smaller samples for larger total sample mass. The improved sampling plans are subject to feasibility constraints or to meet a particular food safety objective.
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Harrand AS, Strawn LK, Illas-Ortiz PM, Wiedmann M, Weller D. Listeria monocytogenes Prevalence Varies More within Fields Than between Fields or over Time on Conventionally Farmed New York Produce Fields. J Food Prot 2020; 83:1958-1966. [PMID: 32609818 PMCID: PMC7995327 DOI: 10.4315/jfp-20-120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/29/2020] [Indexed: 12/11/2022]
Abstract
ABSTRACT Past studies have shown that the on-farm distribution of Listeria monocytogenes is affected by environmental factors (e.g., weather). However, most studies were conducted at large scales (e.g., across farms), whereas few studies examined drivers of L. monocytogenes prevalence at smaller scales (e.g., within a single field). This study was performed to address this knowledge gap by (i) tracking L. monocytogenes distribution in two fields on one farm over a growing season and (ii) identifying factors associated with L. monocytogenes isolation from drag swab, soil, and agricultural water samples. Overall, L. monocytogenes was detected in 78% (21 of 27), 19% (7 of 36), and 8% (37 of 486) of water, drag swab, and soil samples, respectively. All isolates were characterized by pulsed-field gel electrophoresis. Of the 43 types identified, 14 were isolated on multiple sampling visits and/or from multiple sample types, indicating persistence in or repeated introduction into the farm environment during the study. Our findings also suggest that L. monocytogenes prevalence, even at the small spatial scale studied here, (i) was not uniform and (ii) varied more within fields than between fields or over time. This is illustrated by plot (in-field variation), field (between-field variation), and sampling visit (time), accounting for 18, 2, and 3% of variance in odds of isolating L. monocytogenes, respectively. Moreover, according to random forest analysis, water-related factors were among the top-ranked factors associated with L. monocytogenes isolation from all sample types. For example, the likelihood of isolating L. monocytogenes from drag and soil samples increased monotonically as rainfall increased. Overall, findings from this single-farm study suggests that mitigation strategies for L. monocytogenes in produce fields should focus on water-associated risk factors (e.g., rain and distance to water) and be tailored to specific high-risk in-field areas. HIGHLIGHTS
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Affiliation(s)
- A. S. Harrand
- Department of Food Science, Cornell University, 354 Stocking Hall, Ithaca, NY 14853, USA
| | - Laura. K. Strawn
- Department of Food Science, Cornell University, 354 Stocking Hall, Ithaca, NY 14853, USA,Department of Food Science and Technology, Eastern Shore Agriculture Research and Extension Center, Virginia Polytechnic Institute and State University, 33446 Research Drive, Painter, VA 23420, USA
| | | | - Martin Wiedmann
- Department of Food Science, Cornell University, 354 Stocking Hall, Ithaca, NY 14853, USA
| | - Daniel Weller
- Department of Food Science, Cornell University, 354 Stocking Hall, Ithaca, NY 14853, USA,Present affiliation: Department of Biostatistics and Computational Biology, University of Rochester, 265 Crittenden Boulevard, Rochester, NY 14642, USA,Corresponding author: Daniel Weller, /
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7
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Total Coliform and Generic E. coli Levels, and Salmonella Presence in Eight Experimental Aquaponics and Hydroponics Systems: A Brief Report Highlighting Exploratory Data. HORTICULTURAE 2020; 6. [PMID: 34336990 PMCID: PMC8323784 DOI: 10.3390/horticulturae6030042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although many studies have investigated foodborne pathogen prevalence in conventional produce production environments, relatively few have investigated prevalence in aquaponics and hydroponics systems. This study sought to address this knowledge gap by enumerating total coliform and generic E. coli levels, and testing for Salmonella presence in circulating water samples collected from five hydroponic systems and three aquaponic systems (No. of samples = 79). While total coliform levels ranged between 6.3 Most Probable Number (MPN)/100-mL and the upper limit of detection (2496 MPN/100-mL), only three samples had detectable levels of E. coli and no samples had detectable levels of Salmonella. Of the three E. coli positive samples, two samples had just one MPN of E. coli/100-mL while the third had 53.9 MPN of E. coli/100-mL. While the sample size reported here was small and site selection was not randomized, this study adds key data on the microbial quality of aquaponics and hydroponics systems to the literature. Moreover, these data suggest that contamination in these systems occurs at relatively low-levels, and that future studies are needed to more fully explore when and how microbial contamination of aquaponics and hydroponic systems is likely to occur.
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MAJDOUB N, KAAB LBB, VIEIRA AI, FALEIRO ML, EL-GUENDOUZ S, MIGUEL MG. Zn treatment effects on biological potential of fennel bulbs as affected by in vitro digestion process. FOOD SCIENCE AND TECHNOLOGY 2020. [DOI: 10.1590/fst.34918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Adhikari A, Chhetri VS, Camas A. Evaluation of Microbiological Quality of Agricultural Water and Effect of Water Source and Holding Temperature on the Stability of Indicator Organisms' Levels by Seven U.S. Environmental Protection Agency-Approved Methods. J Food Prot 2020; 83:249-255. [PMID: 31944139 DOI: 10.4315/0362-028x.jfp-19-381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/11/2019] [Indexed: 11/11/2022]
Abstract
ABSTRACT The Food Safety Modernization Act Produce Safety Rule requires covered produce growers to monitor the quality of their agricultural water on a regular basis by some U.S. Environmental Protection Agency (EPA)-approved methods recognized by the U.S. Food and Drug Administration. In this study, we evaluated the changes in the population of indicator organisms in surface water up to 6 months, and the effects of water source and holding temperature on the survival of indicator organisms by seven EPA-approved methods (five methods for Escherichia coli and two methods for Enterococcus). The levels of E. coli and Enterococcus in the surface water were variable with sampling month, ranging from 1.61 ± 0.04 to 2.68 ± 0.15 log most probable number (MPN)/100 mL and from undetectable level to 1.19 ± 0.29 log MPN/100 mL, respectively. At 25°C (holding temperature), there were significant reductions (P < 0.05) in E. coli and Enterococcus populations in surface water after 48 and 24 h, respectively, whereas at 4°C, no significant changes in the bacterial populations were observed up to 48 h. Methods 1603, 1604, 1103.1, 10029, and Colilert showed a comparable sensitivity in quantifying E. coli, whereas method 1600 and Enterolert showed a variable sensitivity with the type of water. The results indicated that regular monitoring of agricultural water is essential to examine whether the microbial quality of water is appropriate for its intended use. Water samples should be maintained at 4°C to minimize the changes in microbial populations between sampling and testing. The comparison of the sensitivity of EPA methods for quantifying indicator organisms could provide growers with useful information for choosing the method for their water quality analysis. HIGHLIGHTS
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Affiliation(s)
- Achyut Adhikari
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, Louisiana 70803, USA (ORCID: https://orcid.org/0000-0003-3778-8754 [A.A.])
| | - Vijay Singh Chhetri
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, Louisiana 70803, USA (ORCID: https://orcid.org/0000-0003-3778-8754 [A.A.])
| | - Andrea Camas
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, Louisiana 70803, USA (ORCID: https://orcid.org/0000-0003-3778-8754 [A.A.])
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Lee D, Tertuliano M, Harris C, Vellidis G, Levy K, Coolong T. Salmonella Survival in Soil and Transfer onto Produce via Splash Events. J Food Prot 2019; 82:2023-2037. [PMID: 31692392 DOI: 10.4315/0362-028x.jfp-19-066] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Nearly one-half of foodborne illnesses in the United States can be attributed to fresh produce consumption. The preharvest stage of production presents a critical opportunity to prevent produce contamination in the field from contaminating postharvest operations and exposing consumers to foodborne pathogens. One produce-contamination route that is not often explored is the transfer of pathogens in the soil to edible portions of crops via splash water. We report here on the results from multiple field and microcosm experiments examining the potential for Salmonella contamination of produce crops via splash water, and the effect of soil moisture content on Salmonella survival in soil and concentration in splash water. In field and microcosm experiments, we detected Salmonella for up to 8 to 10 days after inoculation in soil and on produce. Salmonella and suspended solids were detected in splash water at heights of up to 80 cm from the soil surface. Soil-moisture conditions before the splash event influenced the detection of Salmonella on crops after the splash events-Salmonella concentrations on produce after rainfall were significantly higher in wet plots than in dry plots (geometric mean difference = 0.43 CFU/g; P = 0.03). Similarly, concentrations of Salmonella in splash water in wet plots trended higher than concentrations from dry plots (geometric mean difference = 0.67 CFU/100 mL; P = 0.04). These results indicate that splash transfer of Salmonella from soil onto crops can occur and that antecedent soil-moisture content may mediate the efficiency of microbial transfer. Splash transfer of Salmonella may, therefore, pose a hazard to produce safety. The potential for the risk of splash should be further explored in agricultural regions in which Salmonella and other pathogens are present in soil. These results will help inform the assessment of produce safety risk and the development of management practices for the mitigation of produce contamination.
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Affiliation(s)
- Debbie Lee
- Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Road, Atlanta, Georgia 30322
| | | | | | | | - Karen Levy
- Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Road, Atlanta, Georgia 30322
| | - Timothy Coolong
- Department of Horticulture, College of Agricultural & Environmental Sciences, University of Georgia, 2360 Rainwater Road, Tifton, Georgia 31793, USA
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Jeamsripong S, Chase JA, Jay-Russell MT, Buchanan RL, Atwill ER. Experimental In-Field Transfer and Survival of Escherichia coli from Animal Feces to Romaine Lettuce in Salinas Valley, California. Microorganisms 2019; 7:microorganisms7100408. [PMID: 31569566 PMCID: PMC6843402 DOI: 10.3390/microorganisms7100408] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/23/2019] [Accepted: 09/26/2019] [Indexed: 11/20/2022] Open
Abstract
This randomized controlled trial characterized the transfer of E. coli from animal feces and/or furrow water onto adjacent heads of lettuce during foliar irrigation, and the subsequent survival of bacteria on the adaxial surface of lettuce leaves. Two experiments were conducted in Salinas Valley, California: (1) to quantify the transfer of indicator E. coli from chicken and rabbit fecal deposits placed in furrows to surrounding lettuce heads on raised beds, and (2) to quantify the survival of inoculated E. coli on Romaine lettuce over 10 days. E. coli was recovered from 97% (174/180) of lettuce heads to a maximal distance of 162.56 cm (5.33 ft) from feces. Distance from sprinklers to feces, cumulative foliar irrigation, and lettuce being located downwind of the fecal deposit were positively associated, while distance from fecal deposit to lettuce was negatively associated with E. coli transference. E. coli exhibited decimal reduction times of 2.2 and 2.5 days when applied on the adaxial surface of leaves within a chicken or rabbit fecal slurry, respectively. Foliar irrigation can transfer E. coli from feces located in a furrow onto adjacent heads of lettuce, likely due to the kinetic energy of irrigation droplets impacting the fecal surface and/or impacting furrow water contaminated with feces, with the magnitude of E. coli enumerated per head of lettuce influenced by the distance between lettuce and the fecal deposit, cumulative application of foliar irrigation, wind aspect of lettuce relative to feces, and time since final irrigation. Extending the time period between foliar irrigation and harvest, along with a 152.4 cm (5 ft) no-harvest buffer zone when animal fecal material is present, may substantially reduce the level of bacterial contamination on harvested lettuce.
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Affiliation(s)
- Saharuetai Jeamsripong
- Western Center for Food Safety, University of California, Davis, CA 95618, USA (M.T.J.-R.)
- Research Unit in Microbial Food Safety and Antimicrobial Resistance, Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Jennifer A. Chase
- Western Center for Food Safety, University of California, Davis, CA 95618, USA (M.T.J.-R.)
| | - Michele T. Jay-Russell
- Western Center for Food Safety, University of California, Davis, CA 95618, USA (M.T.J.-R.)
| | - Robert L. Buchanan
- Center of Food Safety and Security Systems, College of Agricultural and Natural Resources, University of Maryland, MD 20742, USA;
| | - Edward R. Atwill
- Research Unit in Microbial Food Safety and Antimicrobial Resistance, Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
- Correspondence:
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Weller DL, Kovac J, Kent DJ, Roof S, Tokman JI, Mudrak E, Wiedmann M. A Conceptual Framework for Developing Recommendations for No-Harvest Buffers around In-Field Feces. J Food Prot 2019; 82:1052-1060. [PMID: 31124716 DOI: 10.4315/0362-028x.jfp-18-414] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 02/06/2019] [Indexed: 11/11/2022]
Abstract
HIGHLIGHTS
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Affiliation(s)
- Daniel L Weller
- Department of Food Science, Stocking Hall, Cornell University, Ithaca, New York 14853, USA
| | - Jasna Kovac
- Department of Food Science, Stocking Hall, Cornell University, Ithaca, New York 14853, USA.,Present address: Department of Food Science, The Pennsylvania State University, State College, PA 16802, USA
| | - David J Kent
- Department of Food Science, Stocking Hall, Cornell University, Ithaca, New York 14853, USA
| | - Sherry Roof
- Department of Food Science, Stocking Hall, Cornell University, Ithaca, New York 14853, USA
| | - Jeffrey I Tokman
- Department of Food Science, Stocking Hall, Cornell University, Ithaca, New York 14853, USA
| | - Erika Mudrak
- Statistical Consulting Unit, Cornell University, Ithaca, New York 14853, USA
| | - Martin Wiedmann
- Department of Food Science, Stocking Hall, Cornell University, Ithaca, New York 14853, USA
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13
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Harrand AS, Kovac J, Carroll LM, Guariglia-Oropeza V, Kent DJ, Wiedmann M. Assembly and Characterization of a Pathogen Strain Collection for Produce Safety Applications: Pre-growth Conditions Have a Larger Effect on Peroxyacetic Acid Tolerance Than Strain Diversity. Front Microbiol 2019; 10:1223. [PMID: 31231329 PMCID: PMC6558390 DOI: 10.3389/fmicb.2019.01223] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 05/16/2019] [Indexed: 12/21/2022] Open
Abstract
Effective control of foodborne pathogens on produce requires science-based validation of interventions and control strategies, which typically involves challenge studies with a set of bacterial strains representing the target pathogens or appropriate surrogates. In order to facilitate these types of studies, a produce-relevant strain collection was assembled to represent strains from produce outbreaks or pre-harvest environments, including Listeria monocytogenes (n = 11), Salmonella enterica (n = 23), shiga-toxin producing Escherichia coli (STEC) (n = 13), and possible surrogate organisms (n = 8); all strains were characterized by whole genome sequencing (WGS). Strain diversity was assured by including the 10 most common S. enterica serotypes, L. monocytogenes lineages I-IV, and E. coli O157 as well as selected "non-O157" STEC serotypes. As it has previously been shown that strains and genetic lineages of a pathogen may differ in their ability to survive different stress conditions, a subset of representative strains for each "pathogen group" (e.g., Salmonella, STEC) was selected and assessed for survival of exposure to peroxyacetic acid (PAA) using strains pre-grown under different conditions including (i) low pH, (ii) high salt, (iii) reduced water activity, (iv) different growth phases, (v) minimal medium, and (vi) different temperatures (21°C, 37°C). The results showed that across the three pathogen groups pre-growth conditions had a larger effect on bacterial reduction after PAA exposure as compared to strain diversity. Interestingly, bacteria exposed to salt stress (4.5% NaCl) consistently showed the least reduction after exposure to PAA; however, for STEC, strains pre-grown at 21°C were as tolerant to PAA exposure as strains pre-grown under salt stress. Overall, our data suggests that challenge studies conducted with multi-strain cocktails (pre-grown under a single specific condition) may not necessarily reflect the relevant phenotypic range needed to appropriately assess different intervention strategies.
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Affiliation(s)
| | - Jasna Kovac
- Department of Food Science, Pennsylvania State University, University Park, PA, United States
| | - Laura M. Carroll
- Department of Food Science, Cornell University, Ithaca, NY, United States
| | | | - David J. Kent
- Department of Statistical Science, Cornell University, Ithaca, NY, United States
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, NY, United States
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14
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Chase JA, Partyka ML, Bond RF, Atwill ER. Environmental inactivation and irrigation-mediated regrowth of Escherichia coli O157:H7 on romaine lettuce when inoculated in a fecal slurry matrix. PeerJ 2019; 7:e6591. [PMID: 30867998 PMCID: PMC6410689 DOI: 10.7717/peerj.6591] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/09/2019] [Indexed: 11/20/2022] Open
Abstract
Field trials were conducted in July-August and October 2012 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to romaine lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, California. One-half milliliter of rabbit, chicken, or pig fecal slurry, containing an average of 4.05 × 107 CFU E. coli O157:H7 (C0), was inoculated onto the upper (adaxial) surface of a lower leaf on 288 heads of lettuce per trial immediately following a 2.5 h irrigation event. To estimate the bacterial inactivation rate as a function of time, fecal matrix, irrigation and seasonal climate effects, sets of lettuce heads (n = 28) were sampled each day over 10 days and the concentration of E. coli O157:H7 (Ct) determined. E. coli O157:H7 was detected on 100% of heads during the 10-day duration, with concentrations ranging from ≤340 MPN/head (∼5-log reduction) to >3.45 × 1012 MPN/head (∼5-log growth). Relative to C0, on day 10 (Ct = 12) we observed an overall 2.6-log and 3.2-log mean reduction of E. coli O157:H7 in July and October, respectively. However, we observed relative maximum concentrations due to bacterial growth on day 6 (maximum Ct = 8) apparently stimulated by foliar irrigation on day 5. From this maximum there was a mean 5.3-log and 5.1-log reduction by day 10 (Ct = 12) for the July and October trials, respectively. This study provides insight into the inactivation and growth kinetics of E. coli O157:H7 on romaine lettuce leaves under natural field conditions. This study provides evidence that harvesting within 24 h post irrigation has the potential to increase the concentration of E. coli O157:H7 contamination, if present on heads of romaine lettuce; foliar irrigation can temporarily stimulate substantial regrowth of E. coli O157:H7.
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Affiliation(s)
- Jennifer A. Chase
- Western Center for Food Safety, University of California, Davis, Davis, CA, USA
| | - Melissa L. Partyka
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, USA
| | - Ronald F. Bond
- Western Center for Food Safety, University of California, Davis, Davis, CA, USA
| | - Edward R. Atwill
- Western Center for Food Safety, University of California, Davis, Davis, CA, USA
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15
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Chhetri VS, Fontenot K, Strahan R, Yemmireddy VK, Cason C, Kharel K, Adhikari A. Attachment strength and on-farm die-off rate of Escherichia coli on watermelon surfaces. PLoS One 2019; 14:e0210115. [PMID: 30620744 PMCID: PMC6324798 DOI: 10.1371/journal.pone.0210115] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/17/2018] [Indexed: 01/10/2023] Open
Abstract
Pre-harvest contamination of produce has been a major food safety focus. Insight into the behavior of enteric pathogens on produce in pre-harvest conditions will aid in developing pre-harvest and post-harvest risk management strategies. In this study, the attachment strength (SR) and die-off rate of E. coli on the surface of watermelon fruits and the efficacy of aqueous chlorine treatment against strongly attached E. coli population were investigated. Watermelon seedlings were transplanted into eighteen plots. Prior to harvesting, a cocktail of generic E. coli (ATCC 23716, 25922 and 11775) was inoculated on the surface of the watermelon fruits (n = 162) and the attachment strength (SR) values and the daily die-off rates were examined up to 6 days by attachment assay. After 120 h, watermelon samples were treated with aqueous chlorine (150 ppm free chlorine for 3 min). The SR value of the E. coli cells on watermelon surfaces significantly increased (P<0.05) from 0.04 to 0.99 in the first 24 h, which was primarily due to the decrease in loosely attached population, given that the population of strongly attached cells was constant. Thereafter, there was no significant change in SR values, up to 120 h. The daily die-off rate of E. coli ranged from -0.12 to 1.3 log CFU/cm2. The chlorine treatment reduced the E. coli level by 4.2 log CFU/cm2 (initial level 5.6 log CFU/cm2) and 0.62 log CFU/cm2 (initial level 1.8 log CFU/cm2), on the watermelons that had an attachment time of 30 min and 120 h respectively. Overall, our findings revealed that the population of E. coli on watermelon surfaces declined over time in an agricultural environment. Microbial contamination during pre-harvest stages may promote the formation of strongly attached cells on the produce surfaces, which could influence the efficacy of post-harvest washing and sanitation techniques.
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Affiliation(s)
- Vijay Singh Chhetri
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States of America
| | - Kathryn Fontenot
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States of America
| | - Ronald Strahan
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States of America
| | - Veerachandra K. Yemmireddy
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States of America
| | - Cameron Cason
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States of America
| | - Karuna Kharel
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States of America
| | - Achyut Adhikari
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA, United States of America
- * E-mail:
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16
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Quantitative microbial exposure modelling as a tool to evaluate the impact of contamination level of surface irrigation water and seasonality on fecal hygiene indicator E. coli in leafy green production. Food Microbiol 2018; 75:82-89. [DOI: 10.1016/j.fm.2018.01.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 11/16/2017] [Accepted: 01/19/2018] [Indexed: 11/22/2022]
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