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Jiang X, Wang J. Biological Control of Escherichia coli O157:H7 in Dairy Manure-Based Compost Using Competitive Exclusion Microorganisms. Pathogens 2024; 13:361. [PMID: 38787213 PMCID: PMC11124295 DOI: 10.3390/pathogens13050361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 04/22/2024] [Accepted: 04/25/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Animal manure-based compost is a valuable organic fertilizer and biological soil amendment. To ensure the microbiological safety of compost products, the effectiveness of competitive exclusion microorganisms (CE) in reducing Escherichia coli O157:H7 in dairy manure-based compost was evaluated. METHODS A cocktail of E. coli O157:H7 strains were inoculated into dairy compost along with CE strains isolated from compost, and the reduction in E. coli O157:H7 by CE was determined in compost with 20%, 30%, and 40% moisture levels at 22 °C and 30 °C under laboratory conditions, as well as in fall, winter, and summer seasons under greenhouse settings. RESULTS Under lab conditions, CE addition resulted in 1.1-3.36 log reductions in E. coli O157:H7 in compost, with enhanced pathogen reduction by higher moisture and lower temperature. In the greenhouse, >99% of the E. coli O157:H7 population in compost with ≥30% moisture due to cross-contamination can be effectively inactivated by CE within 2 days during colder seasons. However, it took ≥8 days to achieve the same level of reduction for heat-adapted E. coli O157:H7 cells. CONCLUSIONS Our results demonstrated that the competitive exclusion of microorganisms can be an effective tool for controlling foodborne pathogens in compost and reducing the potential for soil and crop contamination.
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Affiliation(s)
- Xiuping Jiang
- Department of Food, Nutrition, and Packaging Sciences, Clemson University, Clemson, SC 29634, USA
| | - Jingxue Wang
- Department of Food Science and Engineering, Ocean University of China, Qingdao 266003, China;
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2
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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] [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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3
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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: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [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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4
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Iwu CD, Okoh AI. Preharvest Transmission Routes of Fresh Produce Associated Bacterial Pathogens with Outbreak Potentials: A Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:E4407. [PMID: 31717976 PMCID: PMC6888529 DOI: 10.3390/ijerph16224407] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 11/03/2019] [Accepted: 11/06/2019] [Indexed: 02/07/2023]
Abstract
Disease outbreaks caused by the ingestion of contaminated vegetables and fruits pose a significant problem to human health. The sources of contamination of these food products at the preharvest level of agricultural production, most importantly, agricultural soil and irrigation water, serve as potential reservoirs of some clinically significant foodborne pathogenic bacteria. These clinically important bacteria include: Klebsiella spp., Salmonella spp., Citrobacter spp., Shigella spp., Enterobacter spp., Listeria monocytogenes and pathogenic E. coli (and E. coli O157:H7) all of which have the potential to cause disease outbreaks. Most of these pathogens acquire antimicrobial resistance (AR) determinants due to AR selective pressure within the agroecosystem and become resistant against most available treatment options, further aggravating risks to human and environmental health, and food safety. This review critically outlines the following issues with regards to fresh produce; the global burden of fresh produce-related foodborne diseases, contamination between the continuum of farm to table, preharvest transmission routes, AR profiles, and possible interventions to minimize the preharvest contamination of fresh produce. This review reveals that the primary production niches of the agro-ecosystem play a significant role in the transmission of fresh produce associated pathogens as well as their resistant variants, thus detrimental to food safety and public health.
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Affiliation(s)
- Chidozie Declan Iwu
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice 5700, South Africa;
- Applied and Environmental Microbiology Research Group, Department of Biochemistry and Microbiology, University of Fort Hare, Alice 5700, South Africa
| | - Anthony Ifeanyi Okoh
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice 5700, South Africa;
- Applied and Environmental Microbiology Research Group, Department of Biochemistry and Microbiology, University of Fort Hare, Alice 5700, South Africa
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5
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Bezanson G, Mader D, Fillmore S, Bach S, Delaquis P. Reaction of Surrogate Escherichia coli Serotype O157:H7 and Non-O157 Strains to Nutrient Starvation: Variation in Phenotype and Transcription of Stress Response Genes and Behavior on Lettuce Plants in the Field. J Food Prot 2019; 82:1988-2000. [PMID: 31644333 DOI: 10.4315/0362-028x.jfp-19-072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Preharvest contamination with bacteria borne by irrigation water may result in leafy vegetables serving as vehicles for transmission of Shiga toxin-producing Escherichia coli (STEC) to humans. The influence of starvation-associated stress on the behavior of non-toxin-producing strains of E. coli serotype O157:H7 and serotypes O26, O103, O111, and O145 was examined subsequent to their introduction to the phyllosphere of field-grown romaine lettuce as inocula simulating starved (96 h in sterile deionized water) and nutrient-depleted (24 h broth culture) cells. As with E. coli O157:H7, leaf populations of the non-O157 strains declined rapidly during the first 72 h postinoculation, displaying the biphasic decay curve typical of serotype O157:H7 isolates. Preinoculation treatment appeared not to influence decay rates greatly (P > 0.5), but strain-specific differences (persistence period and attachment proficiency) indicated that serotype O103:H2 strain PARC445 was a better survivor. Also assessed was the impact of preinoculation treatment on phenotypes key to leaf colonization and survival and the expression of starvation stress-associated genes. The 96-h starvation period enhanced biofilm formation in one strain but reduced motility and autoinducer 2 formation in all five study strains relative to those characteristics in stationary-phase cells. Transcription of rpoS, dps, uspA, and gapA was reduced significantly (P < 0.05) in starvation-stressed cells relative to that for exponential- and stationary-phase cultures. Strain-specific differences were observed; serotype O103:H2 PARC445 had greater downturns than did serotype O157:H7 and other non-O157 strains. Within this particular cohort, the behavior of the representative serotype O157:H7 strain, PARC443 (ATCC 700728), was not predictive of behavior of non-O157 members of this STEC group.
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Affiliation(s)
- Greg Bezanson
- Agriculture and Agri-Food Canada, Kentville Research and Development Centre, 32 Main Street, Kentville, Nova Scotia, Canada B4N 1J
| | - David Mader
- Agriculture and Agri-Food Canada, Kentville Research and Development Centre, 32 Main Street, Kentville, Nova Scotia, Canada B4N 1J
| | - Sherry Fillmore
- Agriculture and Agri-Food Canada, Kentville Research and Development Centre, 32 Main Street, Kentville, Nova Scotia, Canada B4N 1J
| | - Susan Bach
- Agriculture and Agri-Food Canada, Brandon Research and Development Centre, 2701 Grand Valley Road, Brandon, Manitoba, Canada R7A 5Y3
| | - Pascal Delaquis
- Agriculture and Agri-Food Canada, Summerland Research and Development Centre, 4200 Highway 97, Summerland, British Columbia, Canada V0H 1Z0
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6
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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] [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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7
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Shams DF, Islam S, Shi B, Khan W, Gunawardana B, Saad M, Qasim M, Javed HA, Afridi SG, Naeem M, Khan GS. Characteristics of pipe corrosion scales in untreated water distribution system and effect on water quality in Peshawar, Pakistan. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:5794-5803. [PMID: 30613893 DOI: 10.1007/s11356-018-04099-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 12/27/2018] [Indexed: 06/09/2023]
Abstract
This study investigated the characteristics of iron corrosion scales in pipes at tube well, overhead tank, and consumers' end in older untreated water distribution system in Peshawar city, Pakistan. Effect of water quality conditions on corrosion scales and that of scales on drinking water quality in such systems was also assessed by undertaking a comparison with new piped distribution systems. The scales were analyzed for chemical composition and morphology using X-ray diffraction (XRD), inductively coupled plasma (ICP), and a scanning electron microscope (SEM), while water quality was examined for physicochemical and biological characteristics. The main crystalline phases of corrosion scales were goethite, magnetite, siderite, and quartz. From tube well to consumers' end, goethite increased from 36 up to 48%, quartz declined from 22 to 15%, while magnetite fluctuated and siderite disappeared. Elemental composition of scales showed the deposition of Zn, Al, Mn, Cr, Pb, Cu, As, and Cd with Zn (13.9 g/kg) and Al (3.6 g/kg) in highest proportion. The SEM analysis illustrated the presence of microbial communities indicating the formation of biofilms in the corrosion scales. The significant difference (P < 0.05) in levels of dissolved oxygen (DO), Cl-, SiO44-, electrical conductivity (EC), SO42-, NO3-, alkalinity, hardness, and trace metals between old (DS-O) and new piped systems indicated their role in corrosion scale formation/destabilization and the effect of scale dissolution on water quality. In DS-O, EC, Cu, and Mn were significantly higher (P < 0.05), whereas turbidity, EC, DO, and SiO44- significantly increased from source to consumers' end implying a higher dissolution of scales and lowered corrosion rates in DS-O to utilize SiO44- and DO for iron oxidation.
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Affiliation(s)
- Dilawar Farhan Shams
- Department of Environmental Sciences, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan.
| | - Saeed Islam
- Department of Environmental Sciences, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Baoyou Shi
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Waliullah Khan
- Department of Chemistry, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Buddhika Gunawardana
- Department of Civil Engineering, University of Moratuwa, Moratuwa, 10400, Sri Lanka
| | - Maryam Saad
- Department of Environmental Sciences, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Muhammad Qasim
- Department of Environmental Sciences, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Haider Ali Javed
- Department of Environmental Sciences, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Sahib Gul Afridi
- Department of Biochemistry, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Muhammad Naeem
- Department of Chemistry, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Gul Shahzada Khan
- Department of Chemistry, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
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8
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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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9
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Alegbeleye OO, Singleton I, Sant'Ana AS. Sources and contamination routes of microbial pathogens to fresh produce during field cultivation: A review. Food Microbiol 2018; 73:177-208. [PMID: 29526204 PMCID: PMC7127387 DOI: 10.1016/j.fm.2018.01.003] [Citation(s) in RCA: 245] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/31/2017] [Accepted: 01/02/2018] [Indexed: 12/17/2022]
Abstract
Foodborne illness resulting from the consumption of contaminated fresh produce is a common phenomenon and has severe effects on human health together with severe economic and social impacts. The implications of foodborne diseases associated with fresh produce have urged research into the numerous ways and mechanisms through which pathogens may gain access to produce, thereby compromising microbiological safety. This review provides a background on the various sources and pathways through which pathogenic bacteria contaminate fresh produce; the survival and proliferation of pathogens on fresh produce while growing and potential methods to reduce microbial contamination before harvest. Some of the established bacterial contamination sources include contaminated manure, irrigation water, soil, livestock/ wildlife, and numerous factors influence the incidence, fate, transport, survival and proliferation of pathogens in the wide variety of sources where they are found. Once pathogenic bacteria have been introduced into the growing environment, they can colonize and persist on fresh produce using a variety of mechanisms. Overall, microbiological hazards are significant; therefore, ways to reduce sources of contamination and a deeper understanding of pathogen survival and growth on fresh produce in the field are required to reduce risk to human health and the associated economic consequences.
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Affiliation(s)
| | - Ian Singleton
- School of Applied Sciences, Sighthill Campus, Edinburgh Napier University, Edinburgh, UK
| | - Anderson S Sant'Ana
- Department of Food Science, Faculty of Food Engineering, University of Campinas, Campinas, São Paulo, Brazil.
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10
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Chhetri VS, Fontenot K, Strahan R, Yemmireddy VK, Parraga Estrada KJ, Adhikari A. Effect of surrounding vegetation on microbial survival or die‐off on watermelon surface in an agriculture setting. J Food Saf 2018. [DOI: 10.1111/jfs.12520] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vijay Singh Chhetri
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center Baton Rouge Louisiana
| | - Kathryn Fontenot
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural Center Baton Rouge Louisiana
| | - Ronald Strahan
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural Center Baton Rouge Louisiana
| | - Veerachandra K. Yemmireddy
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center Baton Rouge Louisiana
| | | | - Achyut Adhikari
- School of Nutrition and Food Sciences, Louisiana State University Agricultural Center Baton Rouge Louisiana
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11
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López-Gálvez F, Gil MI, Allende A. Impact of relative humidity, inoculum carrier and size, and native microbiota on Salmonella ser. Typhimurium survival in baby lettuce. Food Microbiol 2018; 70:155-161. [PMID: 29173622 DOI: 10.1016/j.fm.2017.09.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/22/2017] [Accepted: 09/23/2017] [Indexed: 11/26/2022]
Abstract
The effects of relative humidity (RH), fluctuating climate conditions, inoculum size and carrier on the survival of Salmonella enterica serovar Typhimurium on baby lettuce in environmental test chambers were studied. Buffered peptone water (BPW), distilled water (DW), and irrigation water (IW) were compared as inoculum carriers. Additionally, survival of Salmonella in suspensions prepared using filtered and unfiltered IW was assessed. Salmonella Typhimurium survived better on baby lettuce plants at high RH independently of the inoculum size. When lettuce plants were grown under fluctuating environmental conditions, Salmonella survival was similar under both RH conditions. Regarding the inoculum carrier, the inoculated microorganism survived better on lettuce plants when BPW was used as carrier both at high and low RH. Survival rate of Salmonella in IW was affected by the presence of native microbiota. Native microbiota present in IW did not affect survival of Salmonella or the levels of mesophilic bacteria on the baby lettuce leaves. The information obtained in the present study contributes to the knowledge on the effect of environmental conditions on pathogenic bacteria survival on growing edible plants. These results are useful when selecting the methodology to carry out experimental studies on the survival of microbial pathogens under different pre-harvest conditions.
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Affiliation(s)
- Francisco López-Gálvez
- Research Group on Quality, Safety and Bioactivity of Plant Foods, Department of Food Science and Technology, CEBAS-CSIC, Campus Universitario de Espinardo, 30100 Murcia, Spain
| | - Maria Isabel Gil
- Research Group on Quality, Safety and Bioactivity of Plant Foods, Department of Food Science and Technology, CEBAS-CSIC, Campus Universitario de Espinardo, 30100 Murcia, Spain
| | - Ana Allende
- Research Group on Quality, Safety and Bioactivity of Plant Foods, Department of Food Science and Technology, CEBAS-CSIC, Campus Universitario de Espinardo, 30100 Murcia, Spain.
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12
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Wright D, Feibert E, Reitz S, Shock C, Waite-Cusic J. Field Evidence Supporting Conventional Onion Curing Practices as a Strategy To Mitigate Escherichia coli Contamination from Irrigation Water. J Food Prot 2018; 81:369-376. [PMID: 29411999 DOI: 10.4315/0362-028x.jfp-17-231] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The Produce Safety Rule of the U.S. Food Safety Modernization Act includes restrictions on the use of agricultural water of poor microbiological quality. Mitigation options for poor water quality include the application of an irrigation-to-harvest interval of <4 days; however, dry bulb onion production includes an extended irrigation-to-harvest interval (<30 days). This study evaluated conventional curing practices for mitigating Escherichia coli contamination in a field setting. Well water inoculated with rifampin-resistant E. coli (1, 2, or 3 log CFU/mL) was applied to onion fields (randomized block design; n = 5) via drip tape on the final day of irrigation. Onions remained undisturbed for 7 days and were then lifted to the surface to cure for an additional 21 days before harvest. Water, onions, and soil were tested for presence of rifampin-resistant E. coli. One day after irrigation, 13.3% of onions (20 of 150) receiving the poorest quality water (3 log CFU/mL) tested positive for E. coli; this prevalence was reduced to 4% (6 of 150 onions) after 7 days. Regardless of inoculum level, E. coli was not detected on any onions beyond 15 days postirrigation. These results support conventional dry bulb onion curing practices as an effective strategy to mitigate microbiological concerns associated with poor quality irrigation water.
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Affiliation(s)
- Daniel Wright
- 1 Department of Food Science and Technology, 100 Wiegand Hall, Oregon State University, Corvallis, Oregon 97331
| | - Erik Feibert
- 2 Malheur Experiment Station, 595 Onion Avenue, Oregon State University, Ontario, Oregon 97914; and
| | - Stuart Reitz
- 3 Malheur County Extension, 710 S.W. 5th Avenue, Oregon State University, Ontario, Oregon 97914, USA
| | - Clint Shock
- 2 Malheur Experiment Station, 595 Onion Avenue, Oregon State University, Ontario, Oregon 97914; and
| | - Joy Waite-Cusic
- 1 Department of Food Science and Technology, 100 Wiegand Hall, Oregon State University, Corvallis, Oregon 97331
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13
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Shazer A, Stewart D, Deng K, Tortorello M. Approaches toward Identification of Surrogates To Validate Antimicrobial Washes as Preventive Controls for Fresh-Cut Leafy Greens. J Food Prot 2017; 80:1600-1604. [PMID: 28853631 DOI: 10.4315/0362-028x.jfp-17-069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In fresh-cut produce production, antimicrobials may be used during washing to control the risk of cross-contamination by microbial hazards. Surrogate microorganisms have long been used to validate processes, but none have been identified for validating the efficacy of antimicrobial washing of fresh-cut produce. The objective of this study was to develop procedures by which surrogates may be identified for use in validating the control of cross-contamination for fresh-cut lettuce operations. Four microbial characteristics, which may be important factors in cross-contamination events, were quantitatively evaluated in potential surrogate microorganisms for comparison to a reasonably foreseeable hazard, Escherichia coli O157:H7: sensitivity to chlorine in solution, sensitivity to chlorine on lettuce leaf surfaces, shedding from contaminated lettuce leaves into the water during washing, and cross-contamination from inoculated to uninoculated lettuce leaves during chorine washing. A procedure of practical quantitative experiments for comparing the characteristics reduced the original pool of 80 potential strains, which consisted of lactic acid bacteria, probiotics, and isolates obtained from lettuce enrichment cultures, to five strains: Lactobacillus plantarum, Pediococcus pentosaceus, probiotic 22C, and two lettuce enrichment isolates. These strains may be evaluated in additional studies involving comparisons to other reasonably foreseeable hazards and including other potential process variables that should be understood and controlled to prevent cross-contamination in fresh-cut lettuce operations.
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Affiliation(s)
- A Shazer
- 1 U.S. Food and Drug Administration, Division of Food Processing Science and Technology, Illinois Institute of Technology, 6502 South Archer Road, Bedford Park, Illinois 60501, USA
| | - D Stewart
- 1 U.S. Food and Drug Administration, Division of Food Processing Science and Technology, Illinois Institute of Technology, 6502 South Archer Road, Bedford Park, Illinois 60501, USA
| | - K Deng
- 2 Institute for Food Safety and Health, Illinois Institute of Technology, 6502 South Archer Road, Bedford Park, Illinois 60501, USA
| | - M Tortorello
- 1 U.S. Food and Drug Administration, Division of Food Processing Science and Technology, Illinois Institute of Technology, 6502 South Archer Road, Bedford Park, Illinois 60501, USA
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14
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High relative humidity pre-harvest reduces post-harvest proliferation of Salmonella in tomatoes. Food Microbiol 2017; 66:55-63. [DOI: 10.1016/j.fm.2017.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 04/04/2017] [Indexed: 11/21/2022]
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15
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Topalcengiz Z, Strawn LK, Danyluk MD. Microbial quality of agricultural water in Central Florida. PLoS One 2017; 12:e0174889. [PMID: 28399144 PMCID: PMC5388333 DOI: 10.1371/journal.pone.0174889] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/16/2017] [Indexed: 12/02/2022] Open
Abstract
The microbial quality of water that comes into the edible portion of produce is believed to directly relate to the safety of produce, and metrics describing indicator organisms are commonly used to ensure safety. The US FDA Produce Safety Rule (PSR) sets very specific microbiological water quality metrics for agricultural water that contacts the harvestable portion of produce. Validation of these metrics for agricultural water is essential for produce safety. Water samples (500 mL) from six agricultural ponds were collected during the 2012/2013 and 2013/2014 growing seasons (46 and 44 samples respectively, 540 from all ponds). Microbial indicator populations (total coliforms, generic Escherichia coli, and enterococci) were enumerated, environmental variables (temperature, pH, conductivity, redox potential, and turbidity) measured, and pathogen presence evaluated by PCR. Salmonella isolates were serotyped and analyzed by pulsed-field gel electrophoresis. Following rain events, coliforms increased up to 4.2 log MPN/100 mL. Populations of coliforms and enterococci ranged from 2 to 8 and 1 to 5 log MPN/100 mL, respectively. Microbial indicators did not correlate with environmental variables, except pH (P<0.0001). The invA gene (Salmonella) was detected in 26/540 (4.8%) samples, in all ponds and growing seasons, and 14 serotypes detected. Six STEC genes were detected in samples: hly (83.3%), fliC (51.8%), eaeA (17.4%), rfbE (17.4%), stx-I (32.6%), stx-II (9.4%). While all ponds met the PSR requirements, at least one virulence gene from Salmonella (invA-4.8%) or STEC (stx-I-32.6%, stx-II-9.4%) was detected in each pond. Water quality for tested agricultural ponds, below recommended standards, did not guarantee the absence of pathogens. Investigating the relationships among physicochemical attributes, environmental factors, indicator microorganisms, and pathogen presence allows researchers to have a greater understanding of contamination risks from agricultural surface waters in the field.
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Affiliation(s)
- Zeynal Topalcengiz
- Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
| | - Laura K. Strawn
- Department of Food Science and Technology, Agricultural Research and Extension Center, Virginia Tech, 33446 Research drive, Painter, Virginia, United States of America
| | - Michelle D. Danyluk
- Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
- * E-mail:
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16
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Yan R, Liu Y, Gurtler JB, Killinger K, Fan X. Sensitivity of pathogenic and attenuatedE. coliO157:H7 strains to ultraviolet-C light as assessed by conventional plating methods and ethidium monoazide-PCR. J Food Saf 2017. [DOI: 10.1111/jfs.12346] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ruixiang Yan
- USDA, ARS, Eastern Regional Research Center, 600 E. Mermaid Lane; Wyndmoor Pennsylvania 19038
- National Engineering and Technology Research Center for Preservation of Agricultural Products, Tianjin Key Laboratory of Postharvest Physiology and Storage of Agricultural Products; Tianjin 300384 China
| | - Yanhong Liu
- USDA, ARS, Eastern Regional Research Center, 600 E. Mermaid Lane; Wyndmoor Pennsylvania 19038
| | - Joshua B. Gurtler
- USDA, ARS, Eastern Regional Research Center, 600 E. Mermaid Lane; Wyndmoor Pennsylvania 19038
| | - Karen Killinger
- Food and Drug Administration; Center for Food Safety and Applied Nutrition; College Park Maryland 20740
| | - Xuetong Fan
- USDA, ARS, Eastern Regional Research Center, 600 E. Mermaid Lane; Wyndmoor Pennsylvania 19038
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17
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Abstract
This introductory article provides an overview of preharvest food safety activities and initiatives for the past 15 years. The section on traditional areas of preharvest food safety focuses on significant scientific advancements that are a culmination of collaborative efforts (both public health and agriculture) and significant research results. The highlighted advancements provide the foundation for exploring future preharvest areas and for improving and focusing on more specific intervention/control/prevention strategies. Examples include Escherichia coli and cattle, Salmonella and Campylobacter in poultry, and interventions and prevention and control programs. The section on "nontraditional" preharvest food safety areas brings attention to potential emerging food safety issues and to future food safety research directions. These include organic production, the FDA's Produce Rule (water and manure), genomic sequencing, antimicrobial resistance, and performance metrics. The concluding section emphasizes important themes such as strategic planning, coordination, epidemiology, and the need for understanding food safety production as a continuum. Food safety research, whether at the pre- or postharvest level, will continue to be a fascinating complex web of foodborne pathogens, risk factors, and scientific and policy interactions. Food safety priorities and research must continue to evolve with emerging global issues, emerging technologies, and methods but remain grounded in a multidisciplinary, collaborative, and systematic approach.
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18
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López-Gálvez F, Truchado P, Sánchez G, Aznar R, Gil M, Allende A. Occurrence of enteric viruses in reclaimed and surface irrigation water: relationship with microbiological and physicochemical indicators. J Appl Microbiol 2016; 121:1180-8. [DOI: 10.1111/jam.13224] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 06/21/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022]
Affiliation(s)
- F. López-Gálvez
- Research Group on Quality, Safety and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | - P. Truchado
- Research Group on Quality, Safety and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | - G. Sánchez
- Department of Biotechnology; IATA-CSIC; Valencia Spain
- Department of Microbiology and Ecology; University of Valencia; Valencia Spain
| | - R. Aznar
- Department of Biotechnology; IATA-CSIC; Valencia Spain
- Department of Microbiology and Ecology; University of Valencia; Valencia Spain
| | - M.I. Gil
- Research Group on Quality, Safety and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | - A. Allende
- Research Group on Quality, Safety and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
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19
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Development of an Avirulent Salmonella Surrogate for Modeling Pathogen Behavior in Pre- and Postharvest Environments. Appl Environ Microbiol 2016; 82:4100-4111. [PMID: 27129962 DOI: 10.1128/aem.00898-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 04/25/2016] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED Recurrent outbreaks of bacterial gastroenteritis linked to the consumption of fresh fruits and vegetables highlight the paucity of understanding of the ecology of Salmonella enterica under crop production and postharvest conditions. These gaps in knowledge are due, at least in part, to the lack of suitable surrogate organisms for studies for which biosafety level 2 is problematic. Therefore, we constructed and validated an avirulent strain of Salmonella enterica serovar Typhimurium. The strain lacks major Salmonella pathogenicity islands SPI-1, SPI-2, SPI-3, SPI-4, and SPI-5 as well as the virulence plasmid pSLT. Deletions and the absence of genomic rearrangements were confirmed by genomic sequencing, and the surrogate behaved like the parental wild-type strain on selective media. A loss-of-function (phoN) selective marker allowed the differentiation of this strain from wild-type strains on a medium containing a chromogenic substrate for alkaline phosphatase. Lack of virulence was confirmed by oral infection of female BALB/c mice. The strain persisted in tomatoes, cantaloupes, leafy greens, and soil with the same kinetics as the parental wild-type and selected outbreak strains, and it reached similar final population levels. The responses of this strain to heat treatment and disinfectants were similar to those of the wild type, supporting its potential as a surrogate for future studies on the ecology and survival of Salmonella in production and processing environments. IMPORTANCE There is significant interest in understanding the ecology of human pathogens in environments outside of their animal hosts, including the crop production environment. However, manipulative field experiments with virulent human pathogens are unlikely to receive regulatory approval due to the obvious risks. Therefore, we constructed an avirulent strain of S. enterica serovar Typhimurium and characterized it extensively.
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20
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Draper AD, Doores S, Gourama H, LaBorde LF. Microbial Survey of Pennsylvania Surface Water Used for Irrigating Produce Crops. J Food Prot 2016; 79:902-12. [PMID: 27296593 DOI: 10.4315/0362-028x.jfp-15-479] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recent produce-associated foodborne illness outbreaks have been attributed to contaminated irrigation water. This study examined microbial levels in Pennsylvania surface waters used for irrigation, relationships between microbial indicator organisms and water physicochemical characteristics, and the potential use of indicators for predicting the presence of human pathogens. A total of 153 samples taken from surface water sources used for irrigation in southeastern Pennsylvania were collected from 39 farms over a 2-year period. Samples were analyzed for six microbial indicator organisms (aerobic plate count, Enterobacteriaceae, coliform, fecal coliforms, Escherichia coli, and enterococci), two human pathogens (Salmonella and E. coli O157), and seven physical and environmental characteristics (pH, conductivity, turbidity, air and water temperature, and sampling day and 3-day-accumulated precipitation levels). Indicator populations were highly variable and not predicted by water and environmental characteristics. Only five samples were confirmed positive for Salmonella, and no E. coli O157 was detected in any samples. Predictive relationships between microbial indicators and the occurrence of pathogens could therefore not be determined.
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Affiliation(s)
- Audrey D Draper
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Stephanie Doores
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Hassan Gourama
- Division of Science, The Pennsylvania State University-Berks Campus, Reading, Pennsylvania 19610, USA
| | - Luke F LaBorde
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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21
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Ultrasound treatments improve the microbiological quality of water reservoirs used for the irrigation of fresh produce. Food Res Int 2015; 75:140-147. [DOI: 10.1016/j.foodres.2015.05.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/18/2015] [Accepted: 05/27/2015] [Indexed: 12/20/2022]
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22
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Factors affecting cell population density during enrichment and subsequent molecular detection of Salmonella enterica and Escherichia coli O157:H7 on lettuce contaminated during field production. Food Control 2015. [DOI: 10.1016/j.foodcont.2015.01.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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23
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Marvasi M, Noel JT, George AS, Farias MA, Jenkins KT, Hochmuth G, Xu Y, Giovanonni JJ, Teplitski M. Ethylene signalling affects susceptibility of tomatoes to Salmonella. Microb Biotechnol 2014; 7:545-55. [PMID: 24888884 PMCID: PMC4265073 DOI: 10.1111/1751-7915.12130] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/07/2014] [Accepted: 04/19/2014] [Indexed: 12/03/2022] Open
Abstract
Fresh fruits and vegetables are increasingly recognized as important reservoirs of human pathogens, and therefore, significant attention has been directed recently to understanding mechanisms of the interactions between plants and enterics, like Salmonella. A screen of tomato cultivars for their susceptibility to Salmonella revealed significant differences in the ability of this human pathogen to multiply within fruits; expression of the Salmonella genes (cysB, agfB, fadH) involved in the interactions with tomatoes depended on the tomato genotype and maturity stage. Proliferation of Salmonella was strongly reduced in the tomato mutants with defects in ethylene synthesis, perception and signal transduction. While mutation in the ripening-related ethylene receptor Nr resulted only in a modest reduction in Salmonella numbers within tomatoes, strong inhibition of the Salmonella proliferation was observed in rin and nor tomato mutants. RIN and NOR are regulators of ethylene synthesis and ripening. A commercial tomato variety heterozygous for rin was less susceptible to Salmonella under the greenhouse conditions but not when tested in the field over three production seasons.
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Affiliation(s)
- Massimiliano Marvasi
- Soil and Water Science Department, Genetics Institute, University of Florida-IFAS, Gainesville, FL, 32611, USA
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24
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Marvasi M, George AS, Giurcanu M, Hochmuth GJ, Noel JT, Gause E, Teplitski M. Effects of nitrogen and potassium fertilization on the susceptibility of tomatoes to post-harvest proliferation of Salmonella enterica. Food Microbiol 2014; 43:20-7. [PMID: 24929878 DOI: 10.1016/j.fm.2014.03.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 03/21/2014] [Accepted: 03/22/2014] [Indexed: 10/25/2022]
Abstract
Fresh fruits and vegetables are increasingly recognized as vehicles of salmonellosis. Pre- and post-harvest environmental conditions, and physiological, and genetic factors are thought to contribute to the ability of human pathogens to persist in the production environment, attach to, colonize and proliferate in and on raw produce. How field production conditions affect the post-harvest food safety outcomes is not entirely understood. This study tested how varying nitrogen and potassium fertilization levels affected the "susceptibility" of tomatoes to Salmonella infections following the harvest of fruits. Two tomato varieties grown over three seasons under high, medium, and low levels of nitrogen and potassium fertilization in two locations were inoculated with seven strains of Salmonella. Even though the main effects of nitrogen and potassium fertilization on the susceptibility of tomatoes to infections with Salmonella enterica were not statistically significant overall, differences in nitrogen concentrations in plant tissues correlated with the susceptibility of partially ripe tomatoes (cv. Solar Fire) to Salmonella. Tomato maturity and the season in which tomatoes were produced had the strongest effect on the ability of Salmonella to multiply in tomatoes. Tomato phenolics, accumulation of which is known to correlate with rates of the N fertilization, did not inhibit growth of Salmonella in vitro.
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Affiliation(s)
- Massimiliano Marvasi
- Department of Soil and Water Science, University of Florida, Gainesville, FL, USA
| | - Andrée S George
- Department of Soil and Water Science, University of Florida, Gainesville, FL, USA
| | - Mihai Giurcanu
- Statistics Department, University of Florida, Gainesville, FL, USA
| | - George J Hochmuth
- Department of Soil and Water Science, University of Florida, Gainesville, FL, USA
| | - Jason T Noel
- Department of Soil and Water Science, University of Florida, Gainesville, FL, USA
| | - Elizabeth Gause
- Department of Soil and Water Science, University of Florida, Gainesville, FL, USA
| | - Max Teplitski
- Department of Soil and Water Science, University of Florida, Gainesville, FL, USA.
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25
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Factors that affect proliferation of Salmonella in tomatoes post-harvest: the roles of seasonal effects, irrigation regime, crop and pathogen genotype. PLoS One 2013; 8:e80871. [PMID: 24324640 PMCID: PMC3851777 DOI: 10.1371/journal.pone.0080871] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 10/17/2013] [Indexed: 12/22/2022] Open
Abstract
Main Objectives Fresh fruits and vegetables become increasingly recognized as vehicles of human salmonellosis. Physiological, ecological, and environmental factors are all thought to contribute to the ability of Salmonella to colonize fruits and vegetables pre- and post-harvest. The goal of this study was to test how irrigation levels, fruit water congestion, crop and pathogen genotypes affect the ability of Salmonella to multiply in tomatoes post-harvest. Experimental Design Fruits from three tomato varieties, grown over three production seasons in two Florida locations, were infected with seven strains of Salmonella and their ability to multiply post-harvest in field-grown tomatoes was tested. The field experiments were set up as a two-factor factorial split plot experiment, with the whole-plot treatments arranged in a randomized complete-block design. The irrigation treatment (at three levels) was the whole-plot factor, and the split-plot factor was tomato variety, with three levels. The significance of the main, two-way, and three-way interaction effects was tested using the (type III) F-tests for fixed effects. Mean separation for each significant fixed effect in the model was performed using Tukey’s multiple comparison testing procedure. Most Important Discoveries and Significance The irrigation regime per se did not affect susceptibility of the crop to post-harvest proliferation of Salmonella. However, Salmonella grew significantly better in water-congested tissues of green tomatoes. Tomato maturity and genotype, Salmonella genotype, and inter-seasonal differences were the strongest factors affecting proliferation. Red ripe tomatoes were significantly and consistently more conducive to proliferation of Salmonella. Tomatoes harvested in the driest, sunniest season were the most conducive to post-harvest proliferation of the pathogen. Statistically significant interactions between production conditions affected post-harvest susceptibility of the crop to the pathogen. UV irradiation of tomatoes post-harvest promoted Salmonella growth.
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26
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Harris LJ, Berry ED, Blessington T, Erickson M, Jay-Russell M, Jiang X, Killinger K, Michel FC, Millner P, Schneider K, Sharma M, Suslow TV, Wang L, Worobo RW. A framework for developing research protocols for evaluation of microbial hazards and controls during production that pertain to the application of untreated soil amendments of animal origin on land used to grow produce that may be consumed raw. J Food Prot 2013; 76:1062-84. [PMID: 23726206 DOI: 10.4315/0362-028x.jfp-13-007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Application of manure or soil amendments of animal origin (untreated soil amendments; UTSAs) to agricultural land has been a long-standing practice to maintain or improve soil quality through addition of organic matter, nitrogen, and phosphorus. Much smaller quantities of these types of UTSAs are applied to land used for food crops than to land used for animal grain and forage. UTSAs can harbor zoonotic enteric pathogens that may survive for extended periods after application. Additional studies are needed to enhance our understanding of preharvest microbial food safety hazards and control measures pertaining to the application of UTSAs especially for land used to grow produce that may be consumed raw. This document is intended to provide an approach to study design and a framework for defining the scope and type of data required. This document also provides a tool for evaluating the strength of existing data and thus can aid the produce industry and regulatory authorities in identifying additional research needs. Ultimately, this framework provides a means by which researchers can increase consistency among and between studies and facilitates direct comparison of hazards and efficacy of controls applied to different regions, conditions, and practices.
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Affiliation(s)
- Linda J Harris
- Western Center for Food Safety, University of California, One Shields Avenue, Davis, California 95616, USA.
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