Progress 02/15/10 to 02/14/14
Outputs
Target Audience: The target audiences reached include various stakeholders in the produce food safety, including produce growers, produce distributors, researchers and students in academic settings, and members of regulatory agencies. They were reached as part of our informal education activities delivered through presentations/lectures at the Texas Food Safety Conference (2011), the Annual Meeting of the Society for Risk Analysis (2011), the course "Microbiological Safety & Food Safety Plan Development for Fresh Produce (2011)", the Annual Meetings of the International Association for Food Protection (IAFP; 2012 and 2013), and the International Spinach Conference (2012). In particular, many producers/growers were exposed to our research findings at the Texas Food Safety Conference and International Spinach Conference. Additional formal education efforts included delivery of science-based knowledge to graduate students at Texas A&M University, Texas Tech University and Colorado State University who were trained in produce food safety, microbiology, geography, statistics, epidemiologic methods and study designs. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Multiple training and professional development opportunities were provided during the project. Dr. Ivanek (Texas A&M University) mentored Sangshin Park, PhD student, Indumathi Srinath, Research Associate, and Barbara Szonyi, postdoc. Park executed field data collection, managed the data, conducted statistical and epidemiological analyses, and a systematic review of the risk factors for produce contamination with foodborne pathogens and drafted research manuscripts. His research resulted in a PhD dissertation. Srinath extracted landscape and weather data from the National Resource Information databases for use in the statistical and epidemiological analyses. Szonyi assisted with sample collection, analyses and interpretation of results. Dr. Nightingale (Colorado State University and Texas Tech University) mentored Sarah Navratil, a Research Associate, and Alexandra Tudor, a Masters student, whom have been responsible for processing and microbiological analyses of all collected samples. In 2010, Park visited the group of Dr. Nightingale for a week-long training in the field sample collection, processing of samples and microbial detection based on plating and molecular confirmation. Dr. Anciso (Texas AgriLife Extension Service) mentored Ashley Gregory and Arin Bauer, Research Assistants. His group acted as a liaison between the enrolled spinach farms and the research team and assisted with interpretation of the results of the statistical end epidemiological modeling to make sure that the results are relevant to the produce industry. How have the results been disseminated to communities of interest? The results have been disseminated through outreach activities involving produce growers and produce distributors during the “Texas Food Safety Conference", May 10-11, 2011, Austin, TX, the course “Microbiological Safety & Food Safety Plan Development for Fresh Produce”, Dec 1, 2011, Edinburg, TX, and “2012 International Spinach Conference”, Nov 29-30, 2012, San Antonio, TX. In particular, a number of producers/growers were present at the Texas Food Safety Conference and the International Spinach Conference and they were informed about the study findings. Additionally, research results have been distributed through a press release by the Microbe's Journal Highlights of the American Society for Microbiology (http://www.asm.org/index.php/newsroom/88-news-room/journal-tipsheets/91720-researchers-determine-factors-that-influence-spinach-contamination-pre-harvest), and a lay summary spotlighted by the Applied and Environmental Microbiology journal. The press release was picked up and further distributed by a number of news media, including Food Quality News (http://www.foodqualitynews.com/Public-Concerns/Range-of-factors-influence-chance-of-E.coli-in-spinach-pre-harvest-says-study), Science Daily (http://www.sciencedaily.com/releases/2013/06/130620162842.htm ), Homeland Security News Wire (http://www.homelandsecuritynewswire.com/dr20130620-factors-influencing-spinach-e-coli-contamination-before-harvest) and Medical Daily (http://www.medicaldaily.com/e-coli-contamination-found-7-spinach-harvests-how-can-you-prevent-food-poisoning-247027). Finally, an extension publication is in writing. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impact: New and improved strategies are required to control produce contamination with foodborne pathogens at the pre-harvest level and reduce produce-related foodborne illness and outbreaks. This project involved a field study of spinach contamination with major foodborne pathogens (L. monocytogenes, Salmonella, and E. coli O157:H7) and indicator microorganisms. Farms were enrolled in Texas and Colorado as representative states of the southwestern and western US, respectively. Spinach was used as a representative of leafy greens and contamination with generic E. coli was used as an indicator of fecal contamination. The project integrated information on the spinach contamination at the pre-harvest level with information on farm management factors and environment, and the local weather and landscape factors through strategic pairing of microbiological, epidemiological, geospatial, and statistical approaches. The results indicated that the probability of spinach contamination varies by state and it decreases with implementation of hygiene practices for workers and an irrigation lapse time of >5 days. However, it increases with an increasing precipitation over the past month, the application of manure fertilizer, the proximity of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, and the production of hay before spinach planting. The concentration of generic E. coli on contaminated spinach increases with an increasing temperature over the past 9 days and an increasing precipitation over the past month. Overall, the findings support that the probability of generic E. coli contamination in produce at pre-harvest is a result of interplay of farm management, environment and weather factors. Given that a contamination event has occurred, weather conditions determine the microbial count on produce. Thus, the identified local farm management, environment, and weather factors should be considered jointly in development of new and improved good agricultural practices and measures to reduce produce contamination. These practices are expected to improve safety of produce and reduce the incidence of produce-related foodborne illnesses. Completed objectives: (1) Collect spinach samples from fields in Texas and Colorado and test them for contamination with major foodborne pathogens and indicator microorganisms. We completed a 2-year long field study including 12 spinach farms (8 in Texas and 4 in Colorado). Each farm was visited up to 7 times over the study period. We tested approx. 1,000 spinach samples for contamination with foodborne pathogens and indicator microorganisms. Additionally, we tested approx. 200 drag soil samples and 26 samples of irrigation water for pathogen contamination. At each farm visit we administered a questionnaire to obtain information on farm management and environment. For each sampling location we recorded geographic coordinates. The obtained information was organized into a database showing the distribution of the considered microorganisms in spinach and the distribution of pre-harvest management factors and environmental characteristics on enrolled spinach farms. Generic E. coli contamination was found on 7% of tested spinach samples. L. monocytogenes and E. coli O157:H7 were not detected while the prevalence of Salmonella and Listeria spp were exceptionally low. These findings support that preharvest food-borne pathogen contamination occurs at a low frequency (which prevents statistical analysis) but that approximately 1 in 20 spinach samples is contaminated with generic E. coli (an indicator of fecal contamination). (2) Conduct geospatial analysis of the spinach contamination and questionnaire survey data integrated with data obtained from the National Resource Information (NRI) Databases to develop microorganism-specific statistical models for prediction of spinach contamination based on factors describing local management practices and ecological conditions. We conducted spatial modelling of NRI Databases that included weather station records and soil, roads and hydrography maps, to obtain local weather and landscape data for spinach sampling locations. For each sampled location and date of sampling, weather information was obtained from the nearest weather station. We generated 18 variables (describing weather before sample collection on specific days and over an ever increasing period of time) for each of the minimum, maximum and average daily temperatures, precipitation, wind speed and gust. Additionally, we generated variables describing local soil properties (soil acidity, soil texture, slope, and organic matter) and distances to the nearest water body and road. Next, we conducted a series of statistical analyses, including a mixed-effect logistic regression and mixed effect zero-altered negative binomial regression (hurdle model), to predict the odds and extent (concentration) of spinach contamination with generic E. coli as affected by the farm management, environment, weather and landscape factors. We conducted cross-validation of the developed statistical models and assessed their predictive performance using the receiver operating characteristic (ROC) curve for probability of contamination and the normalized root mean squared error (NRMSE) for concentration of generic E. coli on contaminated spinach. The models demonstrated solid predictive performance with an area under the ROC curve of 81% and a preliminary NRMSE of 25%. Weather data obtained from weather stations proved to be useful for predicting the probability and extent of produce contamination. We also conducted a systematic review of existing literature on risk factors for produce contamination with L. monocytogenes, Salmonella, and E. coli O157:H7, which resulted in a comprehensive inventory of the current understanding of risk factors for produce contamination. (3) Use the developed and validated statistical models to identify novel preharvest level strategies for control of foodborne pathogens in spinach. The developed statistical models were used to identify preharvest risk and protective factors for produce contamination with generic E. coli for translation into improved control strategies. Findings indicated that the odds of spinach contamination vary by state. The odds decrease to approximately 1 in 17 with implementation of hygiene practices for farm workers but they increase to approximately 4 in 1 for every mm increase in the average amount of rain over the past 29 days. The odds also increase to 52 in 1 if manure fertilizer was applied on the field. An irrigation lapse time of >5 days reduces the odds of contamination. However the odds of contamination increase due to the proximity (within 10 miles) of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, and the production of hay before spinach planting. Preliminary results indicate that the count of generic E. coli on contaminated spinach increases by 20% for every Celsius degree increase in the average maximum daily temperature over the past 9 days and by 20% for every mm increase in the average amount of rain over the past 29 days. These findings demonstrate that the probability of a fecal contamination event (indicated by the presence of generic E coli) in produce at preharvest is jointly determined by farm management, environment and weather factors. However, once the contamination event has occurred, the microbial concentration on produce depends on weather. These findings will aid in the development of new and improved good agricultural practices and measures to reduce produce contamination based on the appreciation of local weather conditions.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Park, S., Navratil, S., Gregory, A., Bauer, A., Srinath, I., Jun, M., Szonyi, B., Nightingale, K., Anciso, J. and Ivanek, R. Generic Escherichia coli contamination of spinach at the preharvest level: The role of farm management and environmental factors. Applied & Environmental Microbiology. 07/2013, 79(14):4347-4358. Published ahead of print 10 May 2013. doi: 10.1128/AEM.00474-13.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Park, S., Navratil, S., Gregory, A., Bauer, A., Srinath, I., Szonyi, B., Nightingale, K., Anciso, J., Jun, M., Han, D., Lawhon S. and Ivanek, R. Farm management, environment and weather factors jointly affect the probability of spinach contamination with generic Escherichia coli at the preharvest level. Applied & Environmental Microbiology. Published ahead of print 7 February 2014, doi: 10.1128/AEM.03643-13
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Park, S., S. Navratil, A. Gregory, A. Bauer, I. Srinath, M. Jun, B. Szonyi, K. Nightingale, J. Anciso, R. Ivanek. Generic Escherichia coli Contamination of Spinach at the Preharvest Level as Affected by Farm Management and Environmental Factors. 2013 International Association for Food Protection (IAFP) Annual Meeting. North Carolina, U.S., Jul 28-31, 2013
- Type:
Theses/Dissertations
Status:
Awaiting Publication
Year Published:
2013
Citation:
Park, S. PhD Dissertation: Epidemiological investigation of risk factors for microbial contamination in produce at the preharvest level. 2013. Texas A&M University
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2011
Citation:
Ivanek, R. Modeling of landscape and meteorological factors influencing the probability of pathogen isolation from an environmental location: Listeria spp. in the natural environment as a model system. The annual meeting of the Society for Risk Analysis, Charleston, South Carolina. Dec 4-7, 2011
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Progress 02/15/12 to 02/14/13
Outputs
OUTPUTS: Over the past reporting cycle we completed microbial testing of the collected samples. Also, we completed coding of the questionnaire responses for statistical analysis. Based on the geographic coordinates recorded at teach sample collection location we obtained the landscape and weather data from the national resource information databases. We analyzed the questionnaire data and the microbial test results to improve understanding of the farm-environment and -management characteristics that affect the probability of spinach contamination with generic Escherichia coli. Throughout the research process, a doctoral student has been mentored. The student presented the systematic review research conducted as part of the project at the 2012 International Association for Food Protection (IAFP) Annual Meeting, July 22-25, 2012, Providence, RI. Furthermore, Dr. Ivanek presented preliminary results of the study at the 2012 International Spinach Conference, November 29-30, 2012, San Antonio, TX. PARTICIPANTS: Dr. Renata Ivanek (PD), Department of Veterinary Integrative Biosciences, Texas A&M University, has provided oversight of the conducted systematic review, spatial modeling, and statistical and epidemiological analyses. Furthermore, she is mentoring a PhD student, Sang-Shin Park, in the Department of Veterinary Integrative Biosciences. In co-authorship with other members of the project team, Sang-Shin Park published a systematic review of the risk factors for produce contamination with L. monocytogenes, Salmonella, and E. coli O157:H7. Sang-Shin Park has also been in charge of data management and statistical and epidemiological analysis. Ms. Indumathi Srinath extracted landscape and weather data from the national resource information databases to be used in the statistical and epidemiological analysis of the risk factors for produce contamination. Kendra Nightingale (co-PD), Department of Animal and Food Sciences, Texas Tech University, finished microbial testing of all collected samples (both from Texas and Colorado). Additionally, she is mentoring Sarah Navratil, a Research Associate, and Alexandra Tudor, a Masters student, in the Department of Animal and Food Sciences at Texas Tech University, whom have been responsible for processing and microbiological analyses of all collected samples. Dr. Juan Anciso (collaborator), Texas AgriLife Extension Service, Texas A&M System, has been a liaison between the enrolled spinach farmers and the research team and he has assisted with interpretation of the results of the statistical end epidemiological modeling to make sure that the results are relevant to the produce industry. He is mentoring Ashley Gregory, a Research Assistant, in the Texas AgriLife Extension Service. All of the above participants participated in writing of research publications. TARGET AUDIENCES: The results we have obtained thus far in this study have been presented internationally to audiences that include all partners in the produce food safety: researchers, government officials and produce growers and distributors. The specific venues were: the Annual Meeting of the 2012 International Association for Food Protection (IAFP), July 22-25, 2012, Providence, RI, and the International Spinach Conference, November 29-30, 2012, San Antonio, TX. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The conducted systematic review of all published studies on risk factors for produce contamination with L. monocytogenes, Salmonella, and E. coli O157:H7 is the first systematic review in the area of produce food safety which not only provided an invaluable inventory of the considered risk factors for produce contamination but also indicated the areas requiring future research, including the need for establishing reporting standards in the area of produce food safety. The main novelty of the study of the farm-environment and -management characteristics is that the pre-harvest probability of spinach contamination with generic E. coli is affected by the workers' personal hygiene (either directly or as a proxy for another unmeasured factor).
Publications
- 1.Park, S., Szonyi, B., Gautam, R., Nightingale, K., Anciso, J., Ivanek, R.: Risk factors for microbial contamination in fruits and vegetables at the pre-harvest level: A systematic review. Journal of Food Protection, 2012, 75(11):2055-2081.
- 2.Park, S.S, Szonyi, B., Gautam, R., Anciso, J., Nightingale, K., Ivanek, R. Risk factors for microbial contamination in fruits and vegetables at the pre-harvest level: A systematic review. 2012 International Association for Food Protection (IAFP) Annual Meeting, July 22-25, 2012, Providence, RI.
- 3.Park, S.S, Szonyi, B., Gautam, R., Nightingale, K., Anciso, J., Ivanek, R. Systematic review: What do we really know about risk factors for produce contamination at the preharvest level? 2012 International Spinach Conference, November 29-30, 2012, San Antonio, TX.
- 4.Park, S.S, Navratil, S., Gregory, A., Srinath, I., Jun, M., Szonyi, B., Nightingale, K., Anciso, J., Ivanek, R. Generic E. coli in spinach at the preharvest level as affected by farm management and environmental factors. 2012 International Spinach Conference, November 29-30, 2012, San Antonio, TX.
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Progress 02/15/11 to 02/14/12
Outputs
OUTPUTS: Over the past reporting cycle we completed a 2-year longitudinal sample collection where several produce farms in Texas and Colorado were enrolled and visited up to three times during the spinach growing season per year, for up to a total of 6 visits over the study period. At each farm visit, we collected approximately 20 spinach, 4 surface soil and 1 irrigation water samples, for a total of almost 1000 samples collected over the study period. The collected samples are currently being tested for contamination with Listeria monocytogenes, Salmonella, Escherichia coli O157:H7 and indicator microorganisms Listeria spp., generic E. coli, and coliforms. At each farm visit, we also administered a comprehensive questionnaire to obtain information on the farm specific food system signals, such as those related to farm management and worker hygiene practices. The questionnaire responses are now being coded for analysis. For each sampling location we also recorded geographic coordinates in order to be able to match the landscape and weather data from the national resource information databases with the sampling locations. Simultaneously to the above field studies, we conducted a systematic review of risk factors for produce contamination with L. monocytogenes, Salmonella and E. coli O157:H7. Through all of the above activities, a doctoral student has been mentored. A poster outlining progress in this research project has been presented at the annual meeting of the USDA NIFA AFRI project directors, July 2011, Milwaukee, WI. Furthermore, Dr. Ivanek presented preliminary results of the study at the Texas Food Safety Conference, May 2011, Austin, TX; at the Annual Meeting of the Society for Risk Analysis, December 2011, Charleston, SC; and at the "Microbiological Safety & Food Safety Plan Development for Fresh Produce" course, December 2011, Edinburg, TX. PARTICIPANTS: Dr. Renata Ivanek (PD), Department of Veterinary Integrative Biosciences, Texas A&M University, has provided oversight of the design and execution of the longitudinal studies in Colorado and Texas. Furthermore, she is mentoring a PhD student, Sang-Shin Park, in the Department of Veterinary Integrative Biosciences. In co-authorship with other members of the project team, Sang-Shin Park conducted a systematic review of the risk factors for produce contamination with L. monocytogenes, Salmonella, and E. coli O157:H7. Sang-Shin Park has also been in charge of data management and preliminary analysis. Dr. Kendra Nightingale (co-PD), Department of Animal and Food Sciences, Texas Tech University, executed the longitudinal collection of samples and administration of questionnaires in Colorado and microbial testing of all collected samples (both from Texas and Colorado). Additionally, she is mentoring Sarah Navratil, a Research Associate, and Alexandra Tudor, a Masters student, in the Department of Animal and Food Sciences at Texas Tech University, whom have been responsible for sample collection in Colorado, as well as for processing and microbiological analyses of all collected samples. Dr. Juan Anciso (collaborator), Texas AgriLife Extension Service, Texas A&M System, executed the longitudinal collection of samples and administration of questionnaires in Texas. He is mentoring Ashley Gregory, a Research Assistant, in the Texas AgriLife Extension Service. Sang-Shin Park and Ashley Gregory conducted farm visits and sample collection in Texas. TARGET AUDIENCES: Preliminary results of this study have been presented nationally to audiences that include all partners in the produce food safety, namely researchers, government officials and produce growers and distributors. The specific venues include: Texas Food Safety Conference, the Annual Meeting of the Society for Risk Analysis, and the "Microbiological Safety & Food Safety Plan Development for Fresh Produce" course in Edinburg, TX. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The data obtained from the field and laboratory activities outlined under report outputs are being organized into a database that will, when completed, provide information on the distribution of the considered microorganisms in spinach as well as information on the distribution of pre-harvest food system signals associated with spinach production. Systematic review of literature about risk factors for produce contamination with L. monocytogenes, Salmonella, and E. coli O157:H7 resulted in an invaluable inventory of risk factors, including those requiring more research.
Publications
- No publications reported this period
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Progress 02/15/10 to 02/14/11
Outputs
OUTPUTS: Activities were conducted that pertain to the first objective of the project (see Objectives section above), while mentoring a doctoral student. Specifically, data collection during the first year of the planned two-year long longitudinal study has been in progress: several produce farms in Texas and Colorado have been enrolled and visited approximately three times during the spinach growing season. At each farm visit, we have collected approximately 20 spinach, 4 surface soil and 1 irrigation water samples. Geographic coordinates have been recorded for each sampling location. The collected samples have been tested for contamination with Listeria monocytogenes, Salmonella, Escherichia coli O157:H7 and indicator microorganisms Listeria spp., generic E. coli, and coliforms. We designed and administered a questionnaire, prior to each farm visit and sample collection, to obtain information on farm specific food system signals, such as those related to farm management practices. Dr. Ivanek's doctoral student at Texas A&M University visited the group of Dr. Nightingale at the Colorado State University, Fort Collins, CO, for a week-long training in the field sample collection, processing of samples and microbial detection based on plating and molecular confirmation. A poster outlining the research project has been presented at the annual meeting of the USDA NIFA AFRI project directors. PARTICIPANTS: Dr. Renata Ivanek (PD), Department of Veterinary Integrative Biosciences, Texas A&M University, has provided oversight of the design and execution of the longitudinal studies in Colorado and Texas. Furthermore, she is mentoring a PhD student, Sang-Shin Park, in the Department of Veterinary Integrative Biosciences. With Sang-Shin Park, Dr. Ivanek designed the questionnaire for collecting information on the food system signals. Sang-Shin Park has also been in charge of data management. Dr. Kendra Nightingale (co-PD), Department of Animal Sciences, Colorado State University, organized the longitudinal collection of samples and administration of questionnaires in Colorado and microbial testing of all collected samples (both from Texas and Colorado). She also provided a template for development of the questionnaire. Additionally, she is mentoring Sarah Navratil, a Research Associate, and Alexandra Tudor, an Undergraduate Research Assistant, in the Department of Animal Sciences, whom have been responsible for sample collection in Colorado, as well as for processing and microbiological analyses of all collected samples. Dr. Juan Anciso (collaborator), Texas AgriLife Extension Service, Texas A&M System, organized the longitudinal collection of samples and administration of questionnaires in Texas. He also provided information on the specificities in vegetable production for development of the questionnaire. He is mentoring Ashley Gregory, a Research Assistant, in the Texas AgriLife Extension Service. Sang-Shin Park and Ashley Gregory have been conducting farm visits and collecting samples in Texas. Dr. Barbara Szonyi, a post-doctoral fellow mentored by Dr. Ivanek in the Department of Veterinary Integrative Bioscience, assisted with sample collection during a few farm visits in Texas. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The data obtained from the field and laboratory activities outlined under report outputs are being organized into a database that will, when completed, provide information on the distribution of the considered microorganisms in spinach as well as information on the distribution of pre-harvest food system signals associated with spinach production.
Publications
- No publications reported this period
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