Progress 10/01/12 to 06/30/15
Outputs
Target Audience:We interacted with key stakeholders in the artisan and farmstead cheese industry in Vermont. Faculty and graduate students involved in this project also interacted with scientists at 9 national or international research conferences. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?We have had 7 graduate students (4 M.S. and 3 Ph.D.) working on this project. Six of these students have completed theor degrees and one student is scheduled to complete thier degree in 2017. We have had 4 undergradauet students work on this project, completing undergraduate research experiences. How have the results been disseminated to communities of interest?Results have been disseminated through publication in peer-reviewed literature and presentation at scientific meeitngs and conferences. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
1. In the area of food safety and microbial pathogen control we have generated results informing Listeria monocytogenes and Staphylococcus spp. control. L. monocytogenes is a serious, but rare, cause of foodborne illness. Cheeses have been associated with outbreaks of illness caused by L. monocytogenes. We explored behavior of L. monocytogenes inoculated to the surface of a soft washed rind cheese. Despite being inoculated with Listeria sp., presence of this pathogen was not identified through our molecular analysis as being among the top 15 predominant genera. Cultural methods that were used for Listeria detection on the same cheeses using selective media showed the continuous presence of Listeria in the cheese. This result shows the importance of cultural methods in the identification of pathogens as well as the use of molecular methods to identify communities. As a comparison, high level contamination by Pseudomonas was identified and in our data sets it only reached 23% average abundance of at day 21. At day 7 when starter cultures where still in high concentrations, the abundance of Pseudomonas did not exceed 1% overall abundance. Therefore the extent of diversity that can be revealed within a food sample or microbial community is directly affected by the presence of the dominant microbial population. Further work is needed to fully understand these microbial interactions. We investigated the presence of L. monocytogenes on 5 Vermont dairy farms producing milk for artisan cheese manufacture, with the overall goal of identification of the areas where this pathogen most likely survives, and management practices which accomplish mitigation of sources of contamination. Results from this study continue to support the fact that contaminated silage can serve as a reservoir of L. monocytogenes in a dairy farm setting. From our data and field observations, we identified that sources of drinking water for animals serve as niches of L. monocytogenes contamination, and should be targeted as sites of intervention to reduce pathogen incidence. Due to the fact that most Listeria spp. isolates were found in areas that are continually wet, use of water should be kept to a minimum. Protocols that immediately dry these areas (through the use of radiant heating) or disinfection of the areas, should be adhered to and used to control stagnant pools of water in bulk room floors. More importantly, this study has shown the importance of continuous monitoring of environmental sites for the presence of L. monocytogenes. Although monitoring of either the raw milk or the finished products (cheese) is still essential, most raw milk that is destined for artisan cheese making is of high microbiological quality. Similar monitoring should occur for feed samples, especially if silage is used, along with manure, which is destined to be used as a fertilizer in pastures or on fields where edible crops are grown. Such recommendations are consistent with emerging provisions of the Food Safety and Modernization Act. The conclusions from this study can be used by small scale producers on their farms and milking facilities to generate safety protocols that will add a barrier to control this important pathogen. Staphylococcus aureus remains an important mastitis pathogen of dairy cattle and may contaminate dairy products intended for human consumption. Little is known about the epidemiology of S. aureus on dairy farms that produce farmstead cheese. We described the genetic diversity of staphylococci from different sources on 5 Vermont dairy farms producing milk for artisan cheese manufacture. S. aureus intramammary infections were found in 1.4 % of quarters. No S. aureus isolates were obtained from environmental swab samples. Eight different strain types were identified, with different strains isolated from human nares and hands compared to those isolated from quarter milk, bulk tank milk or teat end skin. The farms in this study had a low prevalence of S. aureus bovine intramammary infections. This may be a result of active mastitis control programs and appears to be associated with limited environmental contamination. Strain types were associated with epidemiologic sources (e.g. cattle- and milk-associated strains vs. human associated strains). Beta-lactam resistance was associated with only 2 strain types. Coagulase negative staphylococci (CNS) are increasingly recognized as mastitis pathogens, especially on farms that have controlled S. aureus mastitis. Twenty one species were identified. Common CNS species included: S. auricularis, S. chromogenes, S. equorum, and S. haemolyticus. The 5 farms differed in species diversity and prevalence. On all farms, S. auricularis, S. chromogenes, S. haemolyticus were more likely to be obtained from milk or mammary skin, while S. equorum was more likely to be isolated from environmental sources. Antimicrobial susceptibility profiles varied among the CNS species. Resistance to beta-lactams and lincosamides was commonly identified. Management practices and bacterial species fitness advantages may influence species diversity and prevalence on these farms. Extending these studies to additional farms is required to better understand the diversity of CNS and mastitis risk on small-scale farms that have controlled S. aureus mastitis. 2. In the exploration of consumer beliefs, attitudes, and practices regarding unpasteurized milk products we have generated information describing the motivations and information that guide consumers' decisions regarding raw milk and quantified the extent of raw milk consumption in Vermont. In 2009, legislation in the state of Vermont allowed for on-farm sales of raw milk. Despite this recent change, little is known about the prevalence of raw milk sales in the state or the motivations and information that guide consumers' decisions regarding raw milk. Semi-structured interviews revealed that consumers of raw milk often prioritize personal experiences and local networks over scientific expertise when it comes to raw milk consumption. The process of conducting their own research about raw milk has also helped created a community of more conscious consumers. This Vermont case study can be helpful for examining decision-making in other communities. Results of a general population telephone survey indicate that 11.6% of those surveyed reported consuming raw milk and are on average educated, middle-aged, and middle-income earners in small households. Compared to US Census data, there are no demographic differences between raw milk consumers and the average Vermonter. Motivations for consumption include preference for raw milk's flavor, believed health benefits, and knowing or being a farmer. The primary sources of information are dairy farmers, friends, family, and co-workers. The primary channel through which information is obtained is person-to-person discussions. In a study describing the factors influencing Vermont consumer perceptions of raw milk safety, an association was established between the motivations for raw milk consumption and sustainable agriculture support. Vermonter's appear to be continuing the trend of consuming raw milk at an increasing rate despite continued declarations from local and national public health officials that raw milk is too microbiologically dangerous to justify its consumption. A conceptual model was developed to establish potential factors driving consumer perceptions of raw milk safety and related questions were incorporated into the 2014 Vermonter Poll. Resulting data were analyzed using a Probit regression analysis. We conclude that observable factors have the greatest influence on perceptions of raw milk safety. Specifically, perceived health benefits, presence of children in the household, and taste all influence perceptions of raw milk safety.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Nyarko, E. B. and C.W. Donnelly. 2015. Listeria monocytogenes: strain heterogeneity, methods and challenges of subtyping.J. Food Sci. 80:M2868-M2878.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Nyarko, E. and C. Donnelly. 2014. Differentiation of mixed Listeria strains and also acid-injured, heat-injured, and repaired cells of Listeria monocytogenes using Fourier Transform Infrared spectroscopy. J. Food Prot. 78:540-548.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Nyarko, E., K. Puzey and C. W. Donnelly. 2014. Rapid Differentiation of Listeria monocytogenes Epidemic Clones III and IV and Their Intact Compared with Heat-Killed Populations Using Fourier Transform Infrared Spectroscopy and Chemometrics. J. Food Sci.79:M1189-1196.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
DAmico, D.J., M. J. Druart and C. W. Donnelly. 2014. Comparing the Behavior of Multi-Drug Resistant and Pansusceptible Salmonella During the Production and Aging of a Gouda Cheese Manufactured from Raw Milk. J. Food Prot. 77:903-913.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Nyarko, E., D. DAmico, P. Mach, W. Xia, and C. Donnelly. 2014. Delivery of selective agents via time-delayed release tablets improves recovery of Listeria monocytogenes injured by acid and nitrite. J. Food Prot. 77:772-780.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2015
Citation:
Ph.D. Animal, Nutrition and Food Science. Panos Lekkas. The microbial ecology of Listeria monocytogenes as impacted by three environments: a cheese microbial community, a farm environment, and a soil microbial community. Completed October 2015.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2014
Citation:
M.S. Nutrition and Food Science. Katherine Coale. The fate of Listeria monocytogenes when challenged against the microbial communities found on the surface of soft-ripened, raw milk cheese. Completed May 2014
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2014
Citation:
Ph.D. Animal, Nutrition and Food Science. Esmond Nyarko. Improving detection of Listeria in foods through novel enrichment strategies and FTIR analysis. Completed October 2014.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Lekkas, P. and C.W. Donnelly. 2016. Farm sources of Listeria monocytogenes and impact on the microbial safety of milk destined for artisan cheese production. P2-141 IAFP Annual Meeting, St. Louis, MO. August 2.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Limoges, M. and C. Donnelly. 2016. FDAs compliance program guideline criteria for non-toxigenic Escherichia coli: Impacts on domestic and imported cheese. P2-142 IAFP Annual Meeting, St. Louis, MO. August 2.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Gavell, J. and C. Donnelly. 2016. Validating the efficacy of cleaning procedures used to reduce microbial loads on wooden boards used for cheese aging. P2-143 IAFP Annual Meeting, St. Louis, MO. August 2.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Donnelly,C. and P. Lekkas. 2016. Identification of farm sources of Listeria monocytogenes and incidence in milk destined for artisan cheese production. Problems of Listeriosis ISOPOL XIX, June 14-17, Institut Pasteur, Paris, France
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
DAmico, D.J. and C.W. Donnelly. 2014. Microbiological assessment and intervention to mitigate environmental contamination and Listeria monocytogenes risk in artisan cheese facilities. Abstr. Annual Meeting of the IAFP, Indianapolis, IN.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Nyarko, E., C. Donnelly, P. Mach, W. Xia and D. DAmico. 2013. Delivery of selective agents via time-delayed release tablet improves recovery of Listeria monocytogenes injured by acid and nitrite. Abstr. ISOPOL XVIII, Goa, India, p. 68
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Suozzo, A., & Heiss, S. N. (2013). Going rogue for raw milk: consumer decisions as reflecting,
responding to, or ignoring official knowledge systems. Paper presented at the Pre-Conference on Food and Communication at the annual meeting of the National Communication Association in Washington D. C.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Leamy, R., Heiss, S. N., & Roche, E. (2014). The impact of consumer motivations and sources
of information on unpasteurized milk consumption in Vermont, 2013. Presented at the joint-annual meeting of the Association for the Study of Food and Society (ASFS) and the Agriculture, Food and Human Values Society (AFHVS) in Burlington, Vermont.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2015
Citation:
Alex Helling. MS Thesis, 2015. Sustainable Agriculture in Vermont : Economics of Climate Change Best Management Practices and the Complexity of Consumer Perceptions of Raw Milk
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Mugabi, R. and Barlow, J.W. 2016. Biofilm formation is clonally specific among
Staphylococcus aureus isolated from selected Vermont dairy farms. 116th General Meeting of the American Society for Microbiology, Boston, Massachusetts.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Mugabi, R., Ochoa, A., DAmico, S., Barlow, J. 2015. Epidemiology of coagulase-negative
staphylococci on dairy farms producing farmstead cheese. 115th General Meeting of the
American Society for Microbiology, New Orleans, Louisiana.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Mugabi, R., Hart, S.F., Ochoa, A., and Barlow, J.W. 2015. Genotypes and phenotypes of
Staphylococcus aureus from bulk tank milk on organic dairy farms in Vermont. National
Mastitis Council 54th Annual Meeting, Memphis, TN.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Mugabi, R., Ochoa, A., Hart, S., Barlow, J. 2014. Staphylococcus aureus strain types are
associated with epidemiologic sources on farmstead cheese producing dairy farms in
Vermont. 114th General Meeting of the American Society for Microbiology, Boston Massachusetts.
|
Progress 10/01/14 to 06/30/15
Outputs
Target Audience:We interacted with key stakeholders in the artisan and farmstead cheese industry in Vermont. Faculty and graduate students involved in this project also interacted with scientists at 9 national or international research conferences. Changes/Problems:Two faculty associated with this project have left the University. The extension faculty, Dr. Nwadike, will no longer contribute to this project, and Drs. Barlow and Donnelly will administer the outreach activities. The Engineering faculty, Dr. Hill, has moved to another university. Dr. Barlow plans to maintain collaborations with Dr. Hill and Dr. Hill will continue to contribute to the project under objective 1. What opportunities for training and professional development has the project provided?We have had 7 graduate students (4 M.S. and 3 Ph.D.) working on this project. Six of these students have completed theor degrees and one student is scheduled to complete thier degree in 2017. We have had 4 undergradauet students work on this project, completing undergraduate research experiences. How have the results been disseminated to communities of interest?Results have been disseminated through publication in peer-reviewed literature and presentation at scientific meeitngs and conferences. What do you plan to do during the next reporting period to accomplish the goals?We will continue work on submiting publications and communicating results to stakeholders.
Impacts
What was accomplished under these goals?
1. In the area of food safety and microbial pathogen control we have generated results informing Listeria monocytogenes and Staphylococcus spp. control. L. monocytogenes is a serious, but rare, cause of foodborne illness. Cheeses have been associated with outbreaks of illness caused by L. monocytogenes. We explored behavior of L. monocytogenes inoculated to the surface of a soft washed rind cheese. Despite being inoculated with Listeria sp., presence of this pathogen was not identified through our molecular analysis as being among the top 15 predominant genera. Cultural methods that were used for Listeria detection on the same cheeses using selective media showed the continuous presence of Listeria in the cheese. This result shows the importance of cultural methods in the identification of pathogens as well as the use of molecular methods to identify communities. As a comparison, high level contamination by Pseudomonas was identified and in our data sets it only reached 23% average abundance of at day 21. At day 7 when starter cultures where still in high concentrations, the abundance of Pseudomonas did not exceed 1% overall abundance. Therefore the extent of diversity that can be revealed within a food sample or microbial community is directly affected by the presence of the dominant microbial population. Further work is needed to fully understand these microbial interactions. We investigated the presence of L. monocytogenes on 5 Vermont dairy farms producing milk for artisan cheese manufacture, with the overall goal of identification of the areas where this pathogen most likely survives, and management practices which accomplish mitigation of sources of contamination. Results from this study continue to support the fact that contaminated silage can serve as a reservoir of L. monocytogenes in a dairy farm setting. From our data and field observations, we identified that sources of drinking water for animals serve as niches of L. monocytogenes contamination, and should be targeted as sites of intervention to reduce pathogen incidence. Due to the fact that most Listeria spp. isolates were found in areas that are continually wet, use of water should be kept to a minimum. Protocols that immediately dry these areas (through the use of radiant heating) or disinfection of the areas, should be adhered to and used to control stagnant pools of water in bulk room floors. More importantly, this study has shown the importance of continuous monitoring of environmental sites for the presence of L. monocytogenes. Although monitoring of either the raw milk or the finished products (cheese) is still essential, most raw milk that is destined for artisan cheese making is of high microbiological quality. Similar monitoring should occur for feed samples, especially if silage is used, along with manure, which is destined to be used as a fertilizer in pastures or on fields where edible crops are grown. Such recommendations are consistent with emerging provisions of the Food Safety and Modernization Act. The conclusions from this study can be used by small scale producers on their farms and milking facilities to generate safety protocols that will add a barrier to control this important pathogen. Staphylococcus aureus remains an important mastitis pathogen of dairy cattle and may contaminate dairy products intended for human consumption. Little is known about the epidemiology of S. aureus on dairy farms that produce farmstead cheese. We described the genetic diversity of staphylococci from different sources on 5 Vermont dairy farms producing milk for artisan cheese manufacture. S. aureus intramammary infections were found in 1.4 % of quarters. No S. aureus isolates were obtained from environmental swab samples. Eight different strain types were identified, with different strains isolated from human nares and hands compared to those isolated from quarter milk, bulk tank milk or teat end skin. The farms in this study had a low prevalence of S. aureus bovine intramammary infections. This may be a result of active mastitis control programs and appears to be associated with limited environmental contamination. Strain types were associated with epidemiologic sources (e.g. cattle- and milk-associated strains vs. human associated strains). Beta-lactam resistance was associated with only 2 strain types. Coagulase negative staphylococci (CNS) are increasingly recognized as mastitis pathogens, especially on farms that have controlled S. aureus mastitis. Twenty one species were identified. Common CNS species included: S. auricularis, S. chromogenes, S. equorum, and S. haemolyticus. The 5 farms differed in species diversity and prevalence. On all farms, S. auricularis, S. chromogenes, S. haemolyticus were more likely to be obtained from milk or mammary skin, while S. equorum was more likely to be isolated from environmental sources. Antimicrobial susceptibility profiles varied among the CNS species. Resistance to beta-lactams and lincosamides was commonly identified. Management practices and bacterial species fitness advantages may influence species diversity and prevalence on these farms. Extending these studies to additional farms is required to better understand the diversity of CNS and mastitis risk on small-scale farms that have controlled S. aureus mastitis. 2. In the exploration of consumer beliefs, attitudes, and practices regarding unpasteurized milk products we have generated information describing the motivations and information that guide consumers' decisions regarding raw milk and quantified the extent of raw milk consumption in Vermont. In 2009, legislation in the state of Vermont allowed for on-farm sales of raw milk. Despite this recent change, little is known about the prevalence of raw milk sales in the state or the motivations and information that guide consumers' decisions regarding raw milk. Semi-structured interviews revealed that consumers of raw milk often prioritize personal experiences and local networks over scientific expertise when it comes to raw milk consumption. The process of conducting their own research about raw milk has also helped created a community of more conscious consumers. This Vermont case study can be helpful for examining decision-making in other communities. Results of a general population telephone survey indicate that 11.6% of those surveyed reported consuming raw milk and are on average educated, middle-aged, and middle-income earners in small households. Compared to US Census data, there are no demographic differences between raw milk consumers and the average Vermonter. Motivations for consumption include preference for raw milk's flavor, believed health benefits, and knowing or being a farmer. The primary sources of information are dairy farmers, friends, family, and co-workers. The primary channel through which information is obtained is person-to-person discussions. In a study describing the factors influencing Vermont consumer perceptions of raw milk safety, an association was established between the motivations for raw milk consumption and sustainable agriculture support. Vermonter's appear to be continuing the trend of consuming raw milk at an increasing rate despite continued declarations from local and national public health officials that raw milk is too microbiologically dangerous to justify its consumption. A conceptual model was developed to establish potential factors driving consumer perceptions of raw milk safety and related questions were incorporated into the 2014 Vermonter Poll. Resulting data were analyzed using a Probit regression analysis. We conclude that observable factors have the greatest influence on perceptions of raw milk safety. Specifically, perceived health benefits, presence of children in the household, and taste all influence perceptions of raw milk safety.
Publications
|