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Liao C, Wang L, Quon G. Microbiome-based classification models for fresh produce safety and quality evaluation. Microbiol Spectr 2024; 12:e0344823. [PMID: 38445872 PMCID: PMC10986475 DOI: 10.1128/spectrum.03448-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 02/17/2024] [Indexed: 03/07/2024] Open
Abstract
Small sample sizes and loss of sequencing reads during the microbiome data preprocessing can limit the statistical power of differentiating fresh produce phenotypes and prevent the detection of important bacterial species associated with produce contamination or quality reduction. Here, we explored a machine learning-based k-mer hash analysis strategy to identify DNA signatures predictive of produce safety (PS) and produce quality (PQ) and compared it against the amplicon sequence variant (ASV) strategy that uses a typical denoising step and ASV-based taxonomy strategy. Random forest-based classifiers for PS and PQ using 7-mer hash data sets had significantly higher classification accuracy than those using the ASV data sets. We also demonstrated that the proposed combination of integrating multiple data sets and leveraging a 7-mer hash strategy leads to better classification performance for PS and PQ compared to the ASV method but presents lower PS classification accuracy compared to the feature-selected ASV-based taxonomy strategy. Due to the current limitation of generating taxonomy using the 7-mer hash strategy, the ASV-based taxonomy strategy with remarkably less computing time and memory usage is more efficient for PS and PQ classification and applicable for important taxa identification. Results generated from this study lay the foundation for future studies that wish and need to incorporate and/or compare different microbiome sequencing data sets for the application of machine learning in the area of microbial safety and quality of food. IMPORTANCE Identification of generalizable indicators for produce safety (PS) and produce quality (PQ) improves the detection of produce contamination and quality decline. However, effective sequencing read loss during microbiome data preprocessing and the limited sample size of individual studies restrain statistical power to identify important features contributing to differentiating PS and PQ phenotypes. We applied machine learning-based models using individual and integrated k-mer hash and amplicon sequence variant (ASV) data sets for PS and PQ classification and evaluated their classification performance and found that random forest (RF)-based models using integrated 7-mer hash data sets achieved significantly higher PS and PQ classification accuracy. Due to the limitation of taxonomic analysis for the 7-mer hash, we also developed RF-based models using feature-selected ASV-based taxonomic data sets, which performed better PS classification than those using the integrated 7-mer hash data set. The RF feature selection method identified 480 PS indicators and 263 PQ indicators with a positive contribution to the PS and PQ classification.
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Affiliation(s)
- Chao Liao
- Department of Food Science and Technology, University of California Davis, Davis, California, USA
| | - Luxin Wang
- Department of Food Science and Technology, University of California Davis, Davis, California, USA
| | - Gerald Quon
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California, USA
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Weller DL, Murphy CM, Love TMT, Danyluk MD, Strawn LK. Methodological differences between studies confound one-size-fits-all approaches to managing surface waterways for food and water safety. Appl Environ Microbiol 2024; 90:e0183523. [PMID: 38214516 PMCID: PMC10880618 DOI: 10.1128/aem.01835-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 11/14/2023] [Indexed: 01/13/2024] Open
Abstract
Even though differences in methodology (e.g., sample volume and detection method) have been shown to affect observed microbial water quality, multiple sampling and laboratory protocols continue to be used for water quality monitoring. Research is needed to determine how these differences impact the comparability of findings to generate best management practices and the ability to perform meta-analyses. This study addresses this knowledge gap by compiling and analyzing a data set representing 2,429,990 unique data points on at least one microbial water quality target (e.g., Salmonella presence and Escherichia coli concentration). Variance partitioning analysis was used to quantify the variance in likelihood of detecting each pathogenic target that was uniquely and jointly attributable to non-methodological versus methodological factors. The strength of the association between microbial water quality and select methodological and non-methodological factors was quantified using conditional forest and regression analysis. Fecal indicator bacteria concentrations were more strongly associated with non-methodological factors than methodological factors based on conditional forest analysis. Variance partitioning analysis could not disentangle non-methodological and methodological signals for pathogenic Escherichia coli, Salmonella, and Listeria. This suggests our current perceptions of foodborne pathogen ecology in water systems are confounded by methodological differences between studies. For example, 31% of total variance in likelihood of Salmonella detection was explained by methodological and/or non-methodological factors, 18% was jointly attributable to both methodological and non-methodological factors. Only 13% of total variance was uniquely attributable to non-methodological factors for Salmonella, highlighting the need for standardization of methods for microbiological water quality testing for comparison across studies.IMPORTANCEThe microbial ecology of water is already complex, without the added complications of methodological differences between studies. This study highlights the difficulty in comparing water quality data from projects that used different sampling or laboratory methods. These findings have direct implications for end users as there is no clear way to generalize findings in order to characterize broad-scale ecological phenomenon and develop science-based guidance. To best support development of risk assessments and guidance for monitoring and managing waters, data collection and methods need to be standardized across studies. A minimum set of data attributes that all studies should collect and report in a standardized way is needed. Given the diversity of methods used within applied and environmental microbiology, similar studies are needed for other microbiology subfields to ensure that guidance and policy are based on a robust interpretation of the literature.
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Affiliation(s)
- Daniel L. Weller
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, New York, USA
- Department of Food Science and Technology, Virginia Tech, Blacksburg, Virginia, USA
| | - Claire M. Murphy
- Department of Food Science and Technology, Virginia Tech, Blacksburg, Virginia, USA
| | - Tanzy M. T. Love
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, New York, USA
| | - Michelle D. Danyluk
- Department of Food Science and Human Nutrition, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, USA
| | - Laura K. Strawn
- Department of Food Science and Technology, Virginia Tech, Blacksburg, Virginia, USA
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Bodea IM, Cătunescu GM, Palop Gómez A, Fernández Escámez PS, Garre Perez A. Training in tools to develop quantitative microbial risk assessment of ready-to-eat food with a comparison between the Romanian and Spanish food supply chains. EFSA J 2023; 21:e211006. [PMID: 38047124 PMCID: PMC10687766 DOI: 10.2903/j.efsa.2023.e211006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2023] Open
Abstract
The prevention and control of bacterial contamination on ready-to-eat (RTE) fresh produce is an essential task to ensure food safety. Therefore, the development of novel and effective decontamination technologies to ensure microbiological safety of fruits and vegetables has gained considerable attention and new sanitisation methods are needed. The antimicrobial activity of essential oils (EOs) is well documented, but their application in fresh produce remains a challenge due to their hydrophobic nature. Thus, nanoemulsions efficiently contribute to support the use of EOs in foods by enhancing their dispersibility, their contact area and facilitating the introduction into bacterial cells. The combination of these factors ultimately increases their antimicrobial activity. Quantitative microbial risk assessment (QMRA) is gaining more attention as an effective tool to assess and prevent potential risks associated with food-borne pathogens. In this context, the current project aims to study the effectiveness of different washing methods based on nanoemulsified EOs, comparing them against traditional methods, using a QMRA model for Escherichia coli O157:H7 on cherry tomatoes. Different simulations within a stochastic risk assessment model were implemented using the biorisk package for R, aiming to describe microbial behaviour and biological risk along the Romanian and Spanish food supply chains of RTE fresh produce. Nanoemulsions were prepared using oregano and rosemary EOs, each from Romania and Spain. The four nanoemulsions were evaluated as decontamination treatments to control the growth of E. coli O157:H7 on artificially contaminated cherry tomatoes. The decontamination treatments showed encouraging results, comparable to commonly used chlorine solutions. Therefore, oregano and rosemary nanoemulsions are promising and could be a feasible alternative for chlorine solutions in the reduction of microbiological contaminants.
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Affiliation(s)
- Ioana M Bodea
- Department of Technical and Soil Sciences, Faculty of AgricultureUniversity of Agricultural Science and Veterinary Medicine Cluj‐Napoca400372Cluj‐NapocaRomania
| | - Giorgiana M Cătunescu
- Department of Technical and Soil Sciences, Faculty of AgricultureUniversity of Agricultural Science and Veterinary Medicine Cluj‐Napoca400372Cluj‐NapocaRomania
| | - Alfredo Palop Gómez
- Departamento de Ingeniería AgronómicaETSIA‐Universidad Politécnica de CartagenaPaseo Alfonso XIII, 4830203CartagenaSpain
| | - Pablo S Fernández Escámez
- Departamento de Ingeniería AgronómicaETSIA‐Universidad Politécnica de CartagenaPaseo Alfonso XIII, 4830203CartagenaSpain
| | - Alberto Garre Perez
- Departamento de Ingeniería AgronómicaETSIA‐Universidad Politécnica de CartagenaPaseo Alfonso XIII, 4830203CartagenaSpain
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Pizzo JS, Pelvine RA, da Silva ALBR, Mikcha JMG, Visentainer JV, Rodrigues C. Use of Essential Oil Emulsions to Control Escherichia coli O157:H7 in the Postharvest Washing of Lettuce. Foods 2023; 12:2571. [PMID: 37444307 DOI: 10.3390/foods12132571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/22/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023] Open
Abstract
Essential oils (EOs) have strong antibacterial properties and can be potential sanitizers to reduce pathogen load and prevent cross-contamination during postharvest washing. The objective of this study was to investigate the efficacy of emulsions containing oregano (OR; Origanum vulgare) and winter savory (WS; Satureja montana) EOs at different concentrations (0.94 and 1.88 µL/mL) and storage times (0 h, 24 h, and 7 days), in reducing Escherichia coli O157:H7 on the surface of three types of lettuce (romaine, crisphead, and butterhead). The EO emulsions were compared with one no-rinse treatment and three rinse treatments using water, 200 ppm chlorine, and 80 ppm peroxyacetic acid (PAA), respectively, in a simulated washing system. The results showed that while the EO emulsions significantly reduced E. coli O157:H7 on crisphead lettuce over time, not all treatments were effective for romaine and butterhead lettuce. The mixture of OR and WS at concentrations of 0.94 and 1.88 µL/mL was found to be the most effective in reducing E. coli O157:H7 on inoculated lettuce, resulting in reductions of 3.52 and 3.41 log CFU/g, respectively. Furthermore, the PAA and the mixture of OR and WS at 1.88 µL/mL effectively limited bacterial cross-contamination close to the detection limit for all lettuce types during all storage times. These results suggest that OR and WS EOs could serve as potential alternatives to chemical sanitizers for postharvest lettuce washing.
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Affiliation(s)
| | | | | | - Jane Martha Graton Mikcha
- Center for Agricultural Sciences, Postgraduate Program of Food Science, State University of Maringa, Maringa 87020-900, PR, Brazil
| | | | - Camila Rodrigues
- Department of Horticulture, Auburn University, Auburn, AL 36849, USA
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Guerra S, Michelotti M, Signorini S, Rossi G, Procopio T, Truschi S, Lenzi A, Marvasi M. Pre-heated blades for harvesting baby-leaves reduce the risk of Escherichia coli internalization in leaves. J Sci Food Agric 2023; 103:3621-3627. [PMID: 36377360 DOI: 10.1002/jsfa.12335] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 10/11/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Pathogenic enterobacteria can travel through the plant vascular bundles by penetrating from cuts and persisting into ready-to-eat leafy greens. Because the cutting site is the main point of entrance and uptake, we tested how different cutting strategies can reduce bacterial internalization in leaves. Horizontal cuts at the base of the leaves were performed with two different types of tools: the first with a scalpel (by pulling the blade) and the second with a scissor-action that has blades that cuts by gliding against a thicker blade. Scissor-action generally makes closer border cuts. Blades of both types of tools have worked at 25 °C and 200 °C. The present study aimed to determine how these different types of cuts and temperatures affected bacterial uptake in leaves. Experiments were repeated on different plant genotypes and at different wilting stages. RESULTS Our findings showed that cutting baby-leaves with a scissor action at 200 °C significantly reduced the bacterial uptake compared to the not heated (which simulates a mechanized lettuce harvester). The most effective cutting treatments for reducing bacterial uptake were in the order: scissor 200 °C > scissor 25 °C > scalpel 200 °C > scalpel 25 °C. The scissor heated at 200 °C also prevented bacterial uptake on wilted baby-leaves. CONCLUSION The findings of the present study could provide a further contribution in terms of safety during harvest and suggest that a pre-heated blade supports safety during harvest of leafy greens. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Simona Guerra
- Department of Biology, University of Florence, Florence, Italy
| | | | - Sofia Signorini
- Department of Biology, University of Florence, Florence, Italy
| | - Giuseppe Rossi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Tiziana Procopio
- Division Food Safety and Quality Control, Azienda Agricola Cammelli, Florence, Italy
| | - Stefania Truschi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Anna Lenzi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
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Murphy CM, Weller DL, Strawn LK. Salmonella Prevalence Is Strongly Associated with Spatial Factors while Listeria monocytogenes Prevalence Is Strongly Associated with Temporal Factors on Virginia Produce Farms. Appl Environ Microbiol 2023; 89:e0152922. [PMID: 36728439 DOI: 10.1128/aem.01529-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The heterogeneity of produce production environments complicates the development of universal strategies for managing preharvest produce safety risks. Understanding pathogen ecology in different produce-growing regions is important for developing targeted mitigation strategies. This study aimed to identify environmental and spatiotemporal factors associated with isolating Salmonella and Listeria from environmental samples collected from 10 Virginia produce farms. Soil (n = 400), drag swab (n = 400), and irrigation water (n = 120) samples were tested for Salmonella and Listeria, and results were confirmed by PCR. Salmonella serovar and Listeria species were identified by the Kauffmann-White-Le Minor scheme and partial sigB sequencing, respectively. Conditional forest analysis and Bayesian mixed models were used to characterize associations between environmental factors and the likelihood of isolating Salmonella, Listeria monocytogenes (LM), and other targets (e.g., Listeria spp. and Salmonella enterica serovar Newport). Surrogate trees were used to visualize hierarchical associations identified by the forest analyses. Salmonella and LM prevalence was 5.3% (49/920) and 2.3% (21/920), respectively. The likelihood of isolating Salmonella was highest in water samples collected from the Eastern Shore of Virginia with a dew point of >9.4°C. The likelihood of isolating LM was highest in water samples collected in winter from sites where <36% of the land use within 122 m was forest wetland cover. Conditional forest results were consistent with the mixed models, which also found that the likelihood of detecting Salmonella and LM differed between sample type, region, and season. These findings identified factors that increased the likelihood of isolating Salmonella- and LM-positive samples in produce production environments and support preharvest mitigation strategies on a regional scale. IMPORTANCE This study sought to examine different growing regions across the state of Virginia and to determine how factors associated with pathogen prevalence may differ between regions. Spatial and temporal data were modeled to identify factors associated with an increased pathogen likelihood in various on-farm sources. The findings of the study show that prevalence of Salmonella and L. monocytogenes is low overall in the produce preharvest environment but does vary by space (e.g., region in Virginia) and time (e.g., season), and the likelihood of pathogen-positive samples is influenced by different spatial and temporal factors. Therefore, the results support regional or scale-dependent food safety standards and guidance documents for controlling hazards to minimize risk. This study also suggests that water source assessments are important tools for developing monitoring programs and mitigation measures, as spatiotemporal factors differ on a regional scale.
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White E, Kumar GD, da Silva ALBR, Kerr WL, Cimowsky S, Widmer JA, Dunn LL. Postharvest Reduction of Salmonella enterica on Tomatoes Using a Pelargonic Acid Emulsion. Foods 2021; 10:foods10010178. [PMID: 33477287 PMCID: PMC7830531 DOI: 10.3390/foods10010178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 11/16/2022] Open
Abstract
A novel produce wash consisting of pelargonic acid (PEL) emulsions was tested on tomatoes contaminated with a five-serovar Salmonella enterica cocktail. Ability to reduce contamination on the inoculated tomato surface, as well as mitigation of subsequent cross-contamination to uninoculated tomatoes washed in re-used/spent wash water were examined. Sanitizer efficacy was also examined over 1 and 7 d storage time (8 °C, recommended for red ripe tomatoes) and in the presence of 0.5% (w/v) organic load. PEL performed statistically the same (p ≤ 0.05) at both 30 mM and 50 mM concentrations and resulted in greater than 1, 5 and 6 log CFU/g Salmonella reductions at 0 h, 1 d and 7 d, respectively, when compared to a water-only or no rinse (NR) treatment. This was also a significantly greater reduction than was observed due to chlorine (sodium hypochlorite) and peroxyacetic acid (PAA) at all time points (p ≤ 0.01). Organic load had no impact on sanitizer efficacy for all examined treatments. Finally, PEL had a deleterious impact on tomato texture. At 1 d, ca. 5 N and 7 N were required to achieve tomato skin penetration and compression, respectively, compared to >9 N and 15 N required by all other treatments (p ≤ 0.05). While PEL sanitizers effectively reduced inoculated Salmonella and subsequent transfer to uninoculated tomatoes, reformulation may be necessary to prevent deleterious quality impacts on produce.
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Affiliation(s)
- Elizabeth White
- Department of Food Science & Technology, University of Georgia, 100 Cedar St., Athens, GA 30602, USA; (E.W.); (W.L.K.); (S.C.); (J.A.W.)
| | - Govindaraj Dev Kumar
- Center for Food Safety, University of Georgia, 1109 Experiment St, Griffin, GA 30223, USA
- Correspondence: (G.D.K.); (L.L.D.); Tel.: +1-770-467-6094 (G.D.K.); +1-706-542-0993 (L.L.D.)
| | | | - William L. Kerr
- Department of Food Science & Technology, University of Georgia, 100 Cedar St., Athens, GA 30602, USA; (E.W.); (W.L.K.); (S.C.); (J.A.W.)
| | - Samuel Cimowsky
- Department of Food Science & Technology, University of Georgia, 100 Cedar St., Athens, GA 30602, USA; (E.W.); (W.L.K.); (S.C.); (J.A.W.)
| | - J. Andrew Widmer
- Department of Food Science & Technology, University of Georgia, 100 Cedar St., Athens, GA 30602, USA; (E.W.); (W.L.K.); (S.C.); (J.A.W.)
| | - Laurel L. Dunn
- Department of Food Science & Technology, University of Georgia, 100 Cedar St., Athens, GA 30602, USA; (E.W.); (W.L.K.); (S.C.); (J.A.W.)
- Correspondence: (G.D.K.); (L.L.D.); Tel.: +1-770-467-6094 (G.D.K.); +1-706-542-0993 (L.L.D.)
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Bottichio L, Keaton A, Thomas D, Fulton T, Tiffany A, Frick A, Mattioli M, Kahler A, Murphy J, Otto M, Tesfai A, Fields A, Kline K, Fiddner J, Higa J, Barnes A, Arroyo F, Salvatierra A, Holland A, Taylor W, Nash J, Morawski BM, Correll S, Hinnenkamp R, Havens J, Patel K, Schroeder MN, Gladney L, Martin H, Whitlock L, Dowell N, Newhart C, Watkins LF, Hill V, Lance S, Harris S, Wise M, Williams I, Basler C, Gieraltowski L. Shiga Toxin-Producing Escherichia coli Infections Associated With Romaine Lettuce-United States, 2018. Clin Infect Dis 2020; 71:e323-e330. [PMID: 31814028 PMCID: PMC10982825 DOI: 10.1093/cid/ciz1182] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 12/06/2019] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Produce-associated outbreaks of Shiga toxin-producing Escherichia coli (STEC) were first identified in 1991. In April 2018, New Jersey and Pennsylvania officials reported a cluster of STEC O157 infections associated with multiple locations of a restaurant chain. The Centers for Disease Control and Prevention (CDC) queried PulseNet, the national laboratory network for foodborne disease surveillance, for additional cases and began a national investigation. METHODS A case was defined as an infection between 13 March and 22 August 2018 with 1 of the 22 identified outbreak-associated E. coli O157:H7 or E. coli O61 pulsed-field gel electrophoresis pattern combinations, or with a strain STEC O157 that was closely related to the main outbreak strain by whole-genome sequencing. We conducted epidemiologic and traceback investigations to identify illness subclusters and common sources. A US Food and Drug Administration-led environmental assessment, which tested water, soil, manure, compost, and scat samples, was conducted to evaluate potential sources of STEC contamination. RESULTS We identified 240 case-patients from 37 states; 104 were hospitalized, 28 developed hemolytic uremic syndrome, and 5 died. Of 179 people who were interviewed, 152 (85%) reported consuming romaine lettuce in the week before illness onset. Twenty subclusters were identified. Product traceback from subcluster restaurants identified numerous romaine lettuce distributors and growers; all lettuce originated from the Yuma growing region. Water samples collected from an irrigation canal in the region yielded the outbreak strain of STEC O157. CONCLUSIONS We report on the largest multistate leafy greens-linked STEC O157 outbreak in several decades. The investigation highlights the complexities associated with investigating outbreaks involving widespread environmental contamination.
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Affiliation(s)
- Lyndsay Bottichio
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
- CAITTA, Inc., Herndon, Virginia, USA
| | - Amelia Keaton
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Deepam Thomas
- New Jersey Department of Health, Trenton, New Jersey, USA
| | - Tara Fulton
- New Jersey Department of Health, Trenton, New Jersey, USA
| | - Amanda Tiffany
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
- Alaska Division of Public Health, Anchorage, Alaska, USA
| | - Anna Frick
- Alaska Division of Public Health, Anchorage, Alaska, USA
| | - Mia Mattioli
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Amy Kahler
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jennifer Murphy
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Mark Otto
- US Food and Drug Administration, College Park, Maryland, USA
| | - Adiam Tesfai
- US Food and Drug Administration, College Park, Maryland, USA
| | - Angela Fields
- US Food and Drug Administration, College Park, Maryland, USA
| | - Kelly Kline
- Pennsylvania Department of Health, Harrisburg, Pennsylvania, USA
| | - Jennifer Fiddner
- Allegheny County Health Department, Pittsburgh, Pennsylvania, USA
| | - Jeffrey Higa
- California Department of Public Health, Sacramento, California, USA
| | - Amber Barnes
- California Department of Public Health, Sacramento, California, USA
| | - Francine Arroyo
- California Department of Public Health, Sacramento, California, USA
| | | | - April Holland
- County of Placer Health and Human Services, Placer, California, USA
| | - Wendy Taylor
- County of Placer Health and Human Services, Placer, California, USA
| | - June Nash
- Sacramento County Public Health, Sacramento, California, USA
| | - Bozena M Morawski
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
- Idaho Department of Health and Welfare, Boise, Idaho, USA
| | - Sarah Correll
- Central District Health Department, Boise, Idaho, USA
| | - Rachel Hinnenkamp
- Montana Department of Public Health and Human Services, Helena, Montana, USA
| | - Jeffrey Havens
- Montana Department of Public Health and Human Services, Helena, Montana, USA
| | - Kane Patel
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | | | - Lori Gladney
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Haley Martin
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Laura Whitlock
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Natasha Dowell
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
- Eagle Medical Services, LLC, San Antonio, Texas, USA
| | - Corinne Newhart
- US Food and Drug Administration, College Park, Maryland, USA
| | | | - Vincent Hill
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Susan Lance
- US Food and Drug Administration, College Park, Maryland, USA
| | - Stic Harris
- US Food and Drug Administration, College Park, Maryland, USA
| | - Matthew Wise
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Ian Williams
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Colin Basler
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Weller DL, Saylor L, Turkon P. 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; 6:42. [PMID: 34336990 DOI: 10.3390/horticulturae6030042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Chung T, Weller DL, Kovac J. The Composition of Microbial Communities in Six Streams, and Its Association With Environmental Conditions, and Foodborne Pathogen Isolation. Front Microbiol 2020; 11:1757. [PMID: 32849385 PMCID: PMC7403445 DOI: 10.3389/fmicb.2020.01757] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/06/2020] [Indexed: 12/16/2022] Open
Abstract
Surface water used for produce production is a potential source of pre-harvest contamination with foodborne pathogens. Decisions on how to mitigate food safety risks associated with pre-harvest water use currently rely on generic Escherichia coli-based water quality tests, although multiple studies have suggested that E. coli levels are not a suitable indicator of the food safety risks under all relevant environmental conditions. Hence, improved understanding of spatiotemporal variability in surface water microbiota composition is needed to facilitate identification of alternative or supplementary indicators that co-occur with pathogens. To this end, we aimed to characterize the composition of bacterial and fungal communities in the sediment and water fractions of 68 agricultural water samples collected from six New York streams. We investigated potential associations between the composition of microbial communities, environmental factors and Salmonella and/or Listeria monocytogenes isolation. We found significantly different composition of fungal and bacterial communities among sampled streams and among water fractions of collected samples. This indicates that geography and the amount of sediment in a collected water sample may affect its microbial composition, which was further supported by identified associations between the flow rate, turbidity, pH and conductivity, and microbial community composition. Lastly, we identified specific microbial families that were weakly associated with the presence of Salmonella or Listeria monocytogenes, however, further studies on samples from additional streams are needed to assess whether identified families may be used as indicators of pathogen presence.
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Affiliation(s)
- Taejung Chung
- Department of Food Science, The Pennsylvania State University, University Park, PA, United States
- Microbiome Center, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, United States
| | - Daniel L. Weller
- Department of Food Science, Cornell University, Ithaca, NY, United States
| | - Jasna Kovac
- Department of Food Science, The Pennsylvania State University, University Park, PA, United States
- Microbiome Center, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, United States
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11
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Matthews AN, Rogus S, Jha G, Ulery A, Delgado E, Lombard K, Hunter B, Francis B. Heavy metal content of produce grown in San Juan County (New Mexico, USA). J Environ Sci Health B 2020; 55:889-897. [PMID: 32666867 DOI: 10.1080/03601234.2020.1794220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The Animas River Watershed has long received discharges of naturally occurring acid rock drainage; however, on August 5, 2015, three million gallons flowed into the agricultural region of Farmington, New Mexico and the Navajo Nation. Consumers and growers in the region were fearful that produce might absorb heavy metals from contaminated irrigation water originating from these rivers. Samples were collected from the region including corn (n = 30), pumpkin (n = 10), squash (n = 10), and cucumber (n = 10) then processed and tested using inductively coupled plasma-optical emission spectrometry (ICP-OES) for concentrations of nine metals of interest. These include toxic metals: Al, As, and Pb, which were compared to the World Health Organization limits, 18.29 mg d-1, 0.192 mg d-1, and 0.05 mg kg-1, respectively and essential metals: Cr, Fe, Mn, Zn, Ca, and Cu whose levels were compared to the National Academies' dietary references for tolerable upper intake levels. Results indicate that produce grown in the region contained significantly less metal than the allowable limits, except for Pb in two corn samples. This research is the first attempt to monitor and analyze heavy metal absorption of produce in the area.
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Affiliation(s)
- Alyce N Matthews
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
| | - Stephanie Rogus
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
| | - Gaurav Jha
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
| | - April Ulery
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
| | - Efren Delgado
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
| | - Kevin Lombard
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
| | - Barbara Hunter
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
| | - Brandon Francis
- College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico, USA
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12
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Weller D, Brassill N, Rock C, Ivanek R, Mudrak E, Roof S, Ganda E, Wiedmann M. Complex Interactions Between Weather, and Microbial and Physicochemical Water Quality Impact the Likelihood of Detecting Foodborne Pathogens in Agricultural Water. Front Microbiol 2020; 11:134. [PMID: 32117154 PMCID: PMC7015975 DOI: 10.3389/fmicb.2020.00134] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 01/21/2020] [Indexed: 11/13/2022] Open
Abstract
Agricultural water is an important source of foodborne pathogens on produce farms. Managing water-associated risks does not lend itself to one-size-fits-all approaches due to the heterogeneous nature of freshwater environments. To improve our ability to develop location-specific risk management practices, a study was conducted in two produce-growing regions to (i) characterize the relationship between Escherichia coli levels and pathogen presence in agricultural water, and (ii) identify environmental factors associated with pathogen detection. Three AZ and six NY waterways were sampled longitudinally using 10-L grab samples (GS) and 24-h Moore swabs (MS). Regression showed that the likelihood of Salmonella detection (Odds Ratio [OR] = 2.18), and eaeA-stx codetection (OR = 6.49) was significantly greater for MS compared to GS, while the likelihood of detecting L. monocytogenes was not. Regression also showed that eaeA-stx codetection in AZ (OR = 50.2) and NY (OR = 18.4), and Salmonella detection in AZ (OR = 4.4) were significantly associated with E. coli levels, while Salmonella detection in NY was not. Random forest analysis indicated that interactions between environmental factors (e.g., rainfall, temperature, turbidity) (i) were associated with likelihood of pathogen detection and (ii) mediated the relationship between E. coli levels and likelihood of pathogen detection. Our findings suggest that (i) environmental heterogeneity, including interactions between factors, affects microbial water quality, and (ii) E. coli levels alone may not be a suitable indicator of food safety risks. Instead, targeted methods that utilize environmental and microbial data (e.g., models that use turbidity and E. coli levels to predict when there is a high or low risk of surface water being contaminated by pathogens) are needed to assess and mitigate the food safety risks associated with preharvest water use. By identifying environmental factors associated with an increased likelihood of detecting pathogens in agricultural water, this study provides information that (i) can be used to assess when pathogen contamination of agricultural water is likely to occur, and (ii) facilitate development of targeted interventions for individual water sources, providing an alternative to existing one-size-fits-all approaches.
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Affiliation(s)
- Daniel Weller
- Department of Food Science and Technology, Cornell University, Ithaca, NY, United States
| | - Natalie Brassill
- Department of Soil, Water and Environmental Science, University of Arizona, Maricopa, AZ, United States
| | - Channah Rock
- Department of Soil, Water and Environmental Science, University of Arizona, Maricopa, AZ, United States
| | - Renata Ivanek
- Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY, United States
| | - Erika Mudrak
- Cornell Statistical Consulting Unit, Cornell University, Ithaca, NY, United States
| | - Sherry Roof
- Department of Food Science and Technology, Cornell University, Ithaca, NY, United States
| | - Erika Ganda
- Department of Food Science and Technology, Cornell University, Ithaca, NY, United States
| | - Martin Wiedmann
- Department of Food Science and Technology, Cornell University, Ithaca, NY, United States
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13
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Adhikari A, Parraga Estrada KJ, Chhetri VS, Janes M, Fontenot K, Beaulieu JC. Evaluation of ultraviolet (UV-C) light treatment for microbial inactivation in agricultural waters with different levels of turbidity. Food Sci Nutr 2020; 8:1237-1243. [PMID: 32148829 PMCID: PMC7020289 DOI: 10.1002/fsn3.1412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/11/2019] [Accepted: 12/13/2019] [Indexed: 11/18/2022] Open
Abstract
Produce growers using surface or well water to irrigate their crops may require an appropriate water treatment system in place to meet the water quality standard imposed by FSMA Produce Safety Rule. This study evaluated the potential of using ultraviolet (UV-C) treatment in reducing the microbial population in agricultural water. Waters with turbidity levels ranging from 10.93 to 23.32 Nephelometric Turbidity Units (NTU) were prepared by mixing pond water and well water. The waters were inoculated with a cocktail of generic Escherichia coli (ATCC 23716, 25922, and 11775) and then treated with UV-C light (20-60 mJ/cm2). All tested doses of the UV-C treatment reduced the E. coli levels significantly (p < .05) in the water samples with the turbidity levels up to 23.32 NTU. The decrease in the turbidity from 23.32 to 10.93 NTU increased the level of reduction by more than 2.15 log most probable number (MPN)/100 ml). UV-C treatment effectively reduces microbial load in agriculture water; however, turbidity of water may significantly affect the disinfection efficacy. The study also demonstrated that sprinkler system resulted in a higher level of contamination of cantaloupes compared with drip irrigation. The results indicated that UV-C treatment could be a promising strategy in reducing the produce safety risks associated with irrigation water.
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Affiliation(s)
- Achyut Adhikari
- School of Nutrition and Food SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
| | | | - Vijay S. Chhetri
- School of Nutrition and Food SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
| | - Marlene Janes
- School of Nutrition and Food SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
| | - Kathryn Fontenot
- School of Plant, Environmental and Soil SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
| | - John C. Beaulieu
- United States Department of AgricultureAgricultural Research ServiceNew OrleansLAUSA
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14
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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15
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Wall GL, Clements DP, Fisk CL, Stoeckel DM, Woods KL, Bihn EA. Meeting Report: Key Outcomes from a Collaborative Summit on Agricultural Water Standards for Fresh Produce. Compr Rev Food Sci Food Saf 2019; 18:723-737. [PMID: 33336930 DOI: 10.1111/1541-4337.12434] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 12/01/2022]
Abstract
On February 27 to 28, 2018, the Produce Safety Alliance convened a national water summit in Covington, KY to discuss the requirements of the United States Food and Drug Administration's (FDA) Food Safety Modernization Act Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption (Produce Safety Rule [PSR]). The goals of the meeting were to better understand the challenges growers face in implementing the requirements in Subpart E-Agricultural Water and work collaboratively to develop practical solutions to meet fruit and vegetable production needs while protecting public health. To meet these goals, the summit engaged a diverse group of stakeholders including growers, researchers, extension educators, produce industry members, and regulatory personnel. Key outcomes included defining implementation barriers due to diversity in water sources, distribution systems, commodity types, climates, farm size, and production activities. There was an articulated need for science-based solutions, such as the use of agricultural water system assessments and sharing of federal, state, and regional water quality data, to ensure qualitative and quantitative standards reduce microbial risks. These identified challenges and needs resulted in significant debate about whether reopening the PSR-Subpart E for modification or attempting to address concerns through guidance would provide the best mechanism for alleviating concerns. In addition, training, outreach, and technical assistance were identified as vital priorities once the concerns are formally addressed by FDA. The water summit highlighted the critical need for transparency of FDA's progress on reevaluating the Subpart E requirements to help guide growers' decisions regarding the use of agricultural water.
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Affiliation(s)
- Gretchen L Wall
- Produce Safety Alliance, Dept. of Food Science, Cornell Univ., 665 W. North Street, Geneva, NY, 14456, U.S.A
| | - Donna P Clements
- Produce Safety Alliance, Dept. of Food Science, Cornell Univ., 665 W. North Street, Geneva, NY, 14456, U.S.A
| | - Connie L Fisk
- Produce Safety Alliance, Dept. of Food Science, Cornell Univ., 665 W. North Street, Geneva, NY, 14456, U.S.A
| | - Donald M Stoeckel
- Produce Safety Alliance, Dept. of Food Science, Cornell Univ., 665 W. North Street, Geneva, NY, 14456, U.S.A
| | - Kristin L Woods
- Alabama Cooperative Extension System, Auburn University, P.O. Box 40, Grove Hill, AL, 36451, U.S.A
| | - Elizabeth A Bihn
- Produce Safety Alliance, Dept. of Food Science, Cornell Univ., 665 W. North Street, Geneva, NY, 14456, U.S.A
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16
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Liu H, Whitehouse CA, Li B. Presence and Persistence of Salmonella in Water: The Impact on Microbial Quality of Water and Food Safety. Front Public Health 2018; 6:159. [PMID: 29900166 PMCID: PMC5989457 DOI: 10.3389/fpubh.2018.00159] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 05/10/2018] [Indexed: 01/23/2023] Open
Abstract
Salmonella ranks high among the pathogens causing foodborne disease outbreaks. According to the Centers for Disease Control and Prevention, Salmonella contributed to about 53.4% of all foodborne disease outbreaks from 2006 to 2017, and approximately 32.7% of these foodborne Salmonella outbreaks were associated with consumption of produce. Trace-back investigations have suggested that irrigation water may be a source of Salmonella contamination of produce and a vehicle for transmission. Presence and persistence of Salmonella have been reported in surface waters such as rivers, lakes, and ponds, while ground water in general offers better microbial quality for irrigation. To date, culture methods are still the gold standard for detection, isolation and identification of Salmonella in foods and water. In addition to culture, other methods for the detection of Salmonella in water include most probable number, immunoassay, and PCR. The U.S. Food and Drug Administration (FDA) issued the Produce Safety Rule (PSR) in January 2013 based on the Food Safety Modernization Act (FSMA), which calls for more efforts toward enhancing and improving approaches for the prevention of foodborne outbreaks. In the PSR, agricultural water is defined as water used for in a way that is intended to, or likely to, contact covered produce, such as spray, wash, or irrigation. In summary, Salmonella is frequently present in surface water, an important source of water for irrigation. An increasing evidence indicates irrigation water as a source (or a vehicle) for transmission of Salmonella. This pathogen can survive in aquatic environments by a number of mechanisms, including entry into the viable but nonculturable (VBNC) state and/or residing within free-living protozoa. As such, assurance of microbial quality of irrigation water is critical to curtail the produce-related foodborne outbreaks and thus enhance the food safety. In this review, we will discuss the presence and persistence of Salmonella in water and the mechanisms Salmonella uses to persist in the aquatic environment, particularly irrigation water, to better understand the impact on the microbial quality of water and food safety due to the presence of Salmonella in the water environment.
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Affiliation(s)
- Huanli Liu
- Branch of Microbiology, Arkansas Laboratory, Office of Regulatory Affairs, United States Food and Drug Administration, Jefferson, AR, United States
| | - Chris A. Whitehouse
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, United States Food and Drug Administration, Laurel, MD, United States
| | - Baoguang Li
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, United States Food and Drug Administration, Laurel, MD, United States
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17
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Alborzi S, Bastarrachea LJ, Ding Q, Tikekar RV. Inactivation of Escherichia Coli O157:H7 and Listeria Innocua by Benzoic Acid, Ethylenediaminetetraacetic Acid and Their Combination in Model Wash Water and Simulated Spinach Washing. J Food Sci 2018; 83:1032-1040. [PMID: 29488632 DOI: 10.1111/1750-3841.14077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 01/09/2018] [Accepted: 01/15/2018] [Indexed: 11/27/2022]
Abstract
An antimicrobial effect of benzoic acid (BA) and ethylenediaminetetraacetic acid (EDTA) was evaluated as a potential antimicrobial treatment against Escherichia coli O157:H7 and Listeria innocua. A 30 min exposure to the combination of 15 mM BA and 1 mM EDTA at 22 °C resulted in approximately 3 logarithmic reductions in stationary phase E. coli O157:H7. Logarithmic phase E. coli O157:H7 was more sensitive (P < 0.05) to the treatment and 1 mM EDTA alone caused more than 5 logarithmic reductions. L. innocua was also sensitive to a treatment with 15 mM BA alone, which induced 5 logarithmic reductions. By increasing the temperature of the solution containing 15 mM BA and 1 mM EDTA to 40 °C, more than 5 logarithmic reductions in stationary phase E. coli O157:H7 was observed after 5 min of treatment. However, the antimicrobial effect was attenuated (reaching less than 1 logarithmic reductions) at 4 °C. In addition, the combined BA and EDTA treatment retained its antimicrobial effect against E. coli O157:H7 for at least 6 cycles of treatment over 6 days at room temperature (22 °C). In a simulated spinach washing study, 15 mM BA and 1 mM EDTA together were able to prevent cross-contamination of E. coli O157:H7. The results highlight the potential use of combination of BA (15 mM) and EDTA (1 mM) to address microbial risk from E. coli O157:H7 and L. innocua in fresh produce industry. PRACTICAL APPLICATION This study demonstrates the effectiveness of benzoic acid (BA) and EDTA mixture in inactivating bacteria in the water used for produce washing and reducing the incidence of cross-contamination during washing of fresh produce. Use of BA + EDTA mixture has significant benefits such as: (a) ability to be reused, (b) effectiveness in the presence of organic matter, and (c) reduced need of monitoring wash water conditions such as pH, concentration and organic matter.
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Affiliation(s)
- Solmaz Alborzi
- Dept. of Nutrition and Food Science, Univ. of Maryland, College Park, MD 20742, U.S.A
| | - Luis J Bastarrachea
- Dept. of Nutrition, Dietetics, and Food Sciences, Utah State Univ., Logan, UT 84322, U.S.A
| | - Qiao Ding
- Dept. of Nutrition and Food Science, Univ. of Maryland, College Park, MD 20742, U.S.A
| | - Rohan V Tikekar
- Dept. of Nutrition and Food Science, Univ. of Maryland, College Park, MD 20742, U.S.A
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18
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Cox CE, Brandl MT, de Moraes MH, Gunasekera S, Teplitski M. Production of the Plant Hormone Auxin by Salmonella and Its Role in the Interactions with Plants and Animals. Front Microbiol 2018; 8:2668. [PMID: 29375530 PMCID: PMC5770404 DOI: 10.3389/fmicb.2017.02668] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/21/2017] [Indexed: 11/30/2022] Open
Abstract
The ability of human enteric pathogens to colonize plants and use them as alternate hosts is now well established. Salmonella, similarly to phytobacteria, appears to be capable of producing the plant hormone auxin via an indole-3-pyruvate decarboxylase (IpdC), a key enzyme of the IPyA pathway. A deletion of the Salmonella ipdC significantly reduced auxin synthesis in laboratory culture. The Salmonella ipdC gene was expressed on root surfaces of Medicago truncatula. M. truncatula auxin-responsive GH3::GUS reporter was activated by the wild type Salmonella, and not but the ipdC mutant, implying that the bacterially produced IAA (Indole Acetic Acid) was detected by the seedlings. Seedling infections with the wild type Salmonella caused an increase in secondary root formation, which was not observed in the ipdC mutant. The wild type Salmonella cells were detected as aggregates at the sites of lateral root emergence, whereas the ipdC mutant cells were evenly distributed in the rhizosphere. However, both strains appeared to colonize seedlings well in growth pouch experiments. The ipdC mutant was also less virulent in a murine model of infection. When mice were infected by oral gavage, the ipdC mutant was as proficient as the wild type strain in colonization of the intestine, but it was defective in the ability to cross the intestinal barrier. Fewer cells of the ipdC mutant, compared with the wild type strain, were detected in Peyer's patches, spleen and in the liver. Orthologs of ipdC are found in all Salmonella genomes and are distributed among many animal pathogens and plant-associated bacteria of the Enterobacteriaceae, suggesting a broad ecological role of the IpdC-catalyzed pathway.
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Affiliation(s)
- Clayton E Cox
- Department of Soil and Water Science, University of Florida, Gainesville, FL, United States
| | - Maria T Brandl
- Produce Safety and Microbiology Research Unit, United States Department of Agriculture, Agricultural Research Service, Albany, CA, United States
| | - Marcos H de Moraes
- Department of Soil and Water Science, University of Florida, Gainesville, FL, United States
| | | | - Max Teplitski
- Department of Soil and Water Science, University of Florida, Gainesville, FL, United States.,Smithsonian Marine Station, Ft. Pierce, FL, United States
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19
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Deering AJ, Jack DR, Pruitt RE, Mauer LJ. Movement of Salmonella serovar Typhimurium and E. coli O157:H7 to Ripe Tomato Fruit Following Various Routes of Contamination. Microorganisms 2015; 3:809-25. [PMID: 27682118 PMCID: PMC5023275 DOI: 10.3390/microorganisms3040809] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/28/2015] [Accepted: 11/02/2015] [Indexed: 11/16/2022] Open
Abstract
Salmonella serovars have been associated with the majority of foodborne illness outbreaks involving tomatoes, and E. coli O157:H7 has caused outbreaks involving other fresh produce. Contamination by both pathogens has been thought to originate from all points of the growing and distribution process. To determine if Salmonella serovar Typhimurium and E. coli O157:H7 could move to the mature tomato fruit of different tomato cultivars following contamination, three different contamination scenarios (seed, leaf, and soil) were examined. Following contamination, each cultivar appeared to respond differently to the presence of the pathogens, with most producing few fruit and having overall poor health. The Micro-Tom cultivar, however, produced relatively more fruit and E. coli O157:H7 was detected in the ripe tomatoes for both the seed- and leaf- contaminated plants, but not following soil contamination. The Roma cultivar produced fewer fruit, but was the only cultivar in which E. coli O157:H7 was detected via all three routes of contamination. Only two of the five cultivars produced tomatoes following seed-, leaf-, and soil- contamination with Salmonella Typhimurium, and no Salmonella was found in any of the tomatoes. Together these results show that different tomato cultivars respond differently to the presence of a human pathogen, and for E. coli O157:H7, in particular, tomato plants that are either contaminated as seeds or have a natural opening or a wound, that allows bacteria to enter the leaves can result in plants that have the potential to produce tomatoes that harbor internalized pathogenic bacteria.
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Affiliation(s)
- Amanda J Deering
- Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
| | - Dan R Jack
- Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
| | - Robert E Pruitt
- Department of Botany and Plant Pathology, Purdue University, 915 W. State St., West Lafayette, IN 47907, USA.
| | - Lisa J Mauer
- Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
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20
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Ruengvisesh S, Loquercio A, Castell-Perez E, Taylor TM. Inhibition of Bacterial Pathogens in Medium and on Spinach Leaf Surfaces using Plant-Derived Antimicrobials Loaded in Surfactant Micelles. J Food Sci 2015; 80:M2522-9. [PMID: 26444985 DOI: 10.1111/1750-3841.13085] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/22/2015] [Indexed: 11/28/2022]
Abstract
UNLABELLED Encapsulation of hydrophobic plant essential oil components (EOC) into surfactant micelles can assist the decontamination of fresh produce surfaces from bacterial pathogens during postharvest washing. Loading of eugenol and carvacrol into surfactant micelles of polysorbate 20 (Tween 20), Surfynol® 485W, sodium dodecyl sulfate (SDS), and CytoGuard® LA 20 (CG20) was determined by identification of the EOC/surfactant-specific maximum additive concentration (MAC). Rheological behavior of dilute EOC-containing micelles was then tested to determine micelle tolerance to shearing. Antimicrobial efficacy of EOC micelles against Escherichia coli O157:H7 and Salmonella enterica serotype Saintpaul was first evaluated by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Pathogen-inoculated spinach was treated with eugenol-containing micelles applied via spraying or immersion methods. SDS micelles produced the highest MACs for EOCs, while Tween 20 loaded the lowest amount of EOCs. Micelles demonstrated Newtonian behavior in response to shearing. SDS and CG20-derived micelles containing EOCs produced the lowest MICs and MBCs for pathogens. E. coli O157:H7 and S. Saintpaul were reduced on spinach surfaces by application of eugenol micelles, though no differences in numbers of surviving pathogens were observed when methods of antimicrobial micelle application (spraying, immersion) was compared (P ≥ 0.05). Data suggest eugenol in SDS and CG20 micelles may be useful for produce surface decontamination from bacterial pathogens during postharvest washing. PRACTICAL APPLICATION Antimicrobial essential oil component (EOC)-containing micelles assist the delivery of natural food antimicrobials to food surfaces, including fresh produce, for decontamination of microbial foodborne pathogens. Antimicrobial EOC-loaded micelles were able to inhibit the enteric pathogens Escherichia coli O157:H7 and Salmonella Saintpaul in liquid medium and on spinach surfaces. However, pathogen reduction generally was not impacted by the method of micelle application (spraying, immersion washing) on spinach surfaces.
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Affiliation(s)
- Songsirin Ruengvisesh
- Dept. of Nutrition and Food Science, Texas A&M Univ, College Station, TX, 77843-2253, U.S.A
| | - Andre Loquercio
- Dept. of Nutrition and Food Science, Texas A&M Univ, College Station, TX, 77843-2253, U.S.A
| | - Elena Castell-Perez
- Dept. of Biological and Agricultural Engineering, Texas A&M Univ, College Station, TX, 77843-2117, U.S.A
| | - T Matthew Taylor
- Dept. of Animal Science, Texas A&M Univ, College Station, TX, 77843-2471, U.S.A
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