Progress 11/04/16 to 09/30/21
Outputs
Target Audience:Managers in the food industry and research colleagues have been the traget audience for this research. Labor costs and finding skilled workers are arguably the two of the greatest expense experienced across the food industry. Our research over the past 5 years has illustrated novel and more efficient methods of training employees. We have worked cooperatively with our counterparts in the food industry to help identify their pain points and find solutions. This reserch has covered the gammit from university and college classes ro publications on improved handwashing, use of wearable computers in training to novel methods for enumerating the number of viable but non culturable Listeria that are present in samples of food. Changes/Problems:During working on this project we found out how very difficult it is to change engraned human behavior in something as simple as washing your hands properly. Everyone know how to wash their hands and they have been doing it from an early age. Howeverr, our research and teh vast perpondance of literatuer is that only about 1/3 of the time do employees wash their hand properly. We studied several approaches to increase hand hygine compliance. What opportunities for training and professional development has the project provided?One of the major accomplishments under these goals was the training of six graduate students. A Walton Fellow PhD student worked on training preven training in reducing foodborne disease and is now a Professor at the University of Houston and teaches classes including retail food safety. A second graduate student worked on cues to improve hand hygine and was able to publish his results in an on-line version of Nature. He is not completing his PhD. Three full time em,ployees in the food industry have worked on this project while working full time. A MS student has completed atraing manuscript on minimizing foreigh materials in food while working as the manager in supplier compliance and auditing suppliers. Another graduate student is working on his PhD while working full time as a microbiolotists. He just got published an imvited paper in the prestegious Microorganisms journal on methods to identify Viable But Non-Culturable Listeria. Another MS student is writing his consumer safety comparisions while working as a fulltime product category manager. A second Walton Fellow published > 10 refereed articles and currently works with a major laboratory equipment companyl How have the results been disseminated to communities of interest?Results have been widely distributed to the research community through our publications in a wide-variety of journals. One of the publications on Listeria detection methods has been viewedmore than 200 times. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
American companies spend millions of dollars and countless hours of managers' time training their employees. Most of this is still done in the archaic fashion of having the employees sit in a classroom setting and listen or watch a video of the prescribed training. Why do companies persist in doing this--even when they likely know that this style of training produces abysmal results and almost no change in the employees' long-term behavior. Most of this training is because employers feel they "have to" either as directed by upper level management or one of the supplier audit requirements like the Global Food Safety Initiative. All of the audit compliance packages have specific, often overlapping, training and documentation requirements. During the past 5 years this research project as sought to improve this situation. Examples are: Developed knife training videos for new employees beginning working in poultry cut-up plants. This was a joint training project with a major poultry processor, Global Campus and the US Poultry Foundation Studied the root cause analysis of why employees refuse to wash their hands. Much of the root cause is a perceived lack of time. They felt they needed to complete the next task rather than spend 45 seconds washing their hands. To improve long-term compliance with proper hand hygiene we published several manuscripts that sought to understand the barriers to proper hand hygiene and provide solutions. In addition we investigated the use of computer assisted training through the use of Google Glasses which are wearable computers and we developed a video game to encourage hand washing. Finally, we documented the increased in the rate and retention of employees learning using training that was recorded from the employees' personal perspective. We started by programing a wearable computer that permits the employee to see the training materials in the first person perspective, allows the trainer to "see what the employee sees" as they are taking the training and enables two-way communication between the trainer and the employee all during the training. American companies spend millions of dollars and countless hours of managers' time training their employees. Most of this is still done in the archaic fashion of having the employees sit in a classroom setting and listen or watch a video of the prescribed training. Why do companies persist in doing this--even when they likely know that this style of training produces abysmal results and almost no change in the employees' long-term behavior. Most of this training is because employers feel they "have to" either as directed by upper level management or one of the supplier audit requirements like the Global Food Safety Initiative. All of the audit compliance packages have specific, often overlapping, training and documentation requirements. During the past 5 years this research project as sought to improve this situation. Examples are: Developed knife training videos for new employees beginning working in poultry cut-up plants. This was a joint training project with a major poultry processor, Global Campus and the US Poultry Foundation Studied the root cause analysis of why employees refuse to wash their hands. Much of the root cause is a perceived lack of time. They felt they needed to complete the next task rather than spend 45 seconds washing their hands. To improve long-term compliance with proper hand hygiene we published several manuscripts that sought to understand the barriers to proper hand hygiene and provide solutions. In addition we investigated the use of computer assisted training through the use of Google Glasses which are wearable computers and we developed a video game to encourage hand washing. Finally, we documented the increased in the rate and retention of employees learning using training that was recorded from the employees' personal perspective. We started by programing a wearable computer that permits the employee to see the training materials in the first person perspective, allows the trainer to "see what the employee sees" as they are taking the training and enables two-way communication between the trainer and the employee all during the training.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Nathan E. Wideman, James D. Oliver, Philip Glen Crandall*, and Nathan A. Jarvis. 2021. Detection and Potential Virulence of Viable but Non-Culturable (VBNC) Listeria monocytogenes: A Review. Microorganisms 2021, 9, 194. https://doi.org/10.3390/ microorganisms 9010194.
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Progress 10/01/19 to 09/30/20
Outputs
Target Audience:Target audiences are managers and professional trainers in the food and allied industries who we reached with our presentations, published papers and phone conversationsl Changes/Problems:COVID 19 has severely hampered research is this area What opportunities for training and professional development has the project provided?Our 2016 publication, has been cited 16 times in the past 3 years as an indication of the interest in this area in our research findings. How have the results been disseminated to communities of interest?Publications, emails and phone conversations in addition to Face 2 Face meetings before the pandemic What do you plan to do during the next reporting period to accomplish the goals? What do you plan to do during the next reporting period to accomplish the goals? research-related goals for 2021 will include the following activities: Serve as primary author on three refereed research publications. Serve as principal investigator or co-PI on two competitive research/development funded grants. These proposals will focus on building training capacity with our research team in Haiti. As opportunities become available, present findings at international, national, and/or regional research conferences. We have been invited to write a review on VBNC for a special edition of Microbiology on Listeria. We will be expanding this research with a PhD student to put together the methods for examining "persister" Listeria cells in meat processing plants. We are hopeful that we can get back to near normal for our colleagues in the meat industry so we can start our data collection, but much of the timing is not within our control. We were able to build an in-country research team in Haiti during the pandemic! For 2021 we will publish one or two refereed publications on this initial round of research and are extending this research with a 2021 Rice Board proposal. We will continue working with colleagues from Ag Economics and Arkansas rice exporting companies as we plan next years' research projects.
Impacts
What was accomplished under these goals?
Continuously training current and replacement employees is a job responsibility that most managers do not relish. With todays' volatile work environment, turn-over, replacement and new skill trainings are a fact-of life for most managers. It is estimated that American industry spends more than $150 billion dollars on all aspects of employee training.Employing advanced training methods like those described below could save hundreds of millions of dollars in training expenses. Research using Smart Glasses documented a 25% savings in parts assembly training. For small and medium size businesses this is one of their major recurring expenses. I) What if employee training could be made more automated, be available to the employee in a "just-in-time" format when they need the information and be delivered in a first person perspective, typically how the employee actually views the task they are trying to learn. We have just completed a series of research projects designed to make employee training more efficient and effective. We started by programing a wearable computer that permits the employee to see the training materials in the first person perspective, allows the trainer to "see what the employee sees" as they are taking the training and enables two-way communication between the trainer and the employee all during the training. Additional information on these wearable computers is available at: https://www.newegg.com/p/34U-002J-00001?item=9SIAC4X5651006&source=region&nm_mc=knc-googlemkp-pc&cm_mmc=knc-googlemkp-pc-_-pla-digioptix-_-action+cameras-_-9SIAC4X5651006&gclid=CjwKCAiAq8f-BRBtEiwAGr3DgffutnxbvFFmXTtXS77ysldMu1xpAcDH4QRwYvwmklFeRIeSY9h2RhoCoBYQAvD_BwE&gclsrc=aw.ds The employee is able to view the training information in the small screen to the left of the nose piece and it is like looking at a 27" television from 10 feet away--so it feels quite normal. We found a strong preference for learning using the first-person perspective seeing the task as the trainee. Participants were able to master the training sequence much more rapidly and perform the tasks with fewer mistakes. The wearable computers cost a little more than $100 which is a minimal expense for most employee training programs. All employees can receive identical training or have training tailored to their learning styles. Training materials are easily updated and can be transmitted long-distance to remote training sites. II). A second study assessed students' perceptions of a newly developed video game to determine the likelihood to promote increased handwashing. The game was designed to be played while simultaneously washing hands and involved pressing a foot pedal that caused a character to jump over pipes to progress through various levels. Students were shown a video of the game components and how to play it then given a survey based on a variant of the Technology Acceptance Model. Based on a 7- point Likert scale from "1 = Strongly disagree" to "7 = Strongly agree", mean values for preference, perceived ease of use, perceived enjoyment, and perceived usefulness were, respectively, 4.73 ± 1.55, 5.26 ± 1.31, 4.98 ± 1.33, and 4.64 ± 1.56. Students ( n = 100) expressed a positive response towards video game. One third of respondents had an average preference of "Agree" or higher for using the video game in foodservice.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
1. Books, book chapters.
Park, SH, Byungjick, MS, Kim, AE, Ricke, SC, Crandall, PG, Lee, SI, Lee, SO. 2019.Chapter 15 Pectin as an Alternative Feed Additive and Effects on Microbiota. In Safety and Practice for Organic Food. Biswas, D. and Micallef, S. Eds. Pages 305-319.
https://www.elsevier.com/books/safety-and-practice-for-organic-food/biswas/978-0-12-812060-6
2. Peer-reviewed journal articles.
Mauromostakos, A, Crandall, PG, Thompson, KC and OBryan, CA. 2020. Further predictive statistical analysis of a GFSI survey of international food processors. J. of Basic and Applied Research International. 26(2): 39-52. ISSN: 2395-3438 (P), ISSN: 2395-3446
Clark J, Renolds, J and Crandall, PD. 2020. Perceptions of a video game to promote handwashing habits in foodservice. Food Control Vol 107 106772
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Progress 10/01/18 to 09/30/19
Outputs
Target Audience:Target Audience Trainers and educators in the food industry, foodservice industry and Universities. Changes/Problems:Gaps: Most of the aforementioned studies, however, are concerned with what might now be called traditional, computer-assisted training methods. A new type of instructional media involves the use of wearable devices that deliver step-by-step instruction while the trainee performs the action they are seeking to learn. Wearable computers are increasingly being used in the manufacturing and food industries. A wearable computer can be defined as a fully functional, self-powered, self-contained computer that is worn on the body that provides access to information wearable computers may take the form of smart glasses or virtual reality headsets. This technology carries a unique set of educational features. Wearable computers such as smart glasses can provide hands free training that could affect how efficiently training is viewed and executed, potentially reduce training expenses for companies. A new paradigm is emerging that suggests greater organizational outcomes can be achieved by educating employees in the food industry through computer-based training and augmenting worker performance with theassistance of smart glasses. These plausible benefits must be weighed against some of the potential drawbacks associated with wearable computers as an educational tool. To date, little is known of the impact of wearable computers on the food industry or its functionality in a training situation. Understanding the functionality and limitations of using wearable computers for training purposes can help food industry stakeholders make better informed decisions about whether to supplant existing instructional delivery methods with new technology. The objective of this Hatch Project was to understand properties of wearable computer-based foodservice training in comparison with a more traditional, strictly video-based training platform. This study looked at the properties of efficiency, hands-free access to information, and freed-up space in the work environment. Efficiency was evaluated, while hands-free access to information and freed-up space in the work environment were addressed. What opportunities for training and professional development has the project provided?The food industry has new information on which to judge the merits of computer based trainings.Because of the newly enacted (15 Sept 2016) Federal FSMA food safety regulations require that managers of FDA inspected food processing operations and their supply chains ensure all their employees are trained and qualified to perform their assigned duties. Managers must have written training plans to ensure their employees have the necessary combination of education, training, and/or experience that meet the requirements necessary to manufacture, process, pack, or hold clean and safe food. Individuals must receive training in the principles of food hygiene and food safety, including the importance of employee health and personal hygiene. Employee training also plays a critical role in USDA inspected facilities Hazard Analysis and Critical Control Points (HACCP), Good Manufacturing Practices and Sanitation Standard Operating Procedure (SSOP) programs. Recently the National Institute of Food and Agriculture surveyed several establishments and determined that 65% of them characterized training as very important, with highest interest in the areas of HACCP regulatory updates, cleaning and sanitation, detection and control of pathogens and Escherichia coli regulations. Reasons given for not having a training program included lack of time, lack of funds and lack of access to appropriate training resources. How have the results been disseminated to communities of interest?Through our publications in peer reviewed journals Publications in internationally recognized, peer reviewed journals and conservations with our colleagues have helped get the results of this research widely disseminated. Clark, J. and Crandall, P.G. 2019. Educational Affordances of Google Glass as a New Instructional Platform for Foodservice Training," Journal of Foodservice Management and Education. Vol 13(1) 28-32. Published jointly by the Foodservice Systems Management Educational Council and the National Association of College & University Food Service http://fsmec.org/journal/ Clark, J.A., Crandall. P.G., Pellegrino, R. and Shabatura, J.C.. 2019. Assessing Smart Glasses-Based Foodservice Training: An Embodied Learning Theory Approach. Évaluation d'une formation en service alimentaire basée sur des lunettes intelligentes. Canadian Journal of Learning & Technology 45 (2). DOI: https://doi.org/10.21432/cjlt27838 Clark, J. A., Crandall, P.G., and Reynolds, J. (2019). Exploring the influence of food safety climate indicators on handwashing practices of restaurant food handlers. International Journal of Hospitality Management, 77, 187-194. What do you plan to do during the next reporting period to accomplish the goals?We will continue to get research that has been completed published.
Impacts
What was accomplished under these goals?
EyeSucceed, a Washington, DC based training firm has made national press releases on the results of our research and has undertaken a nation-wide validation study to collect supporting data that investing in wearable computer training technology is cost effective. I.Training: Documenting food safety training, especially for new employees is mandatory under FSMA and HACCP. The food industry in general and the poultry industry in this particular must make adaptions to accommodate the needs of a more diverse group of new employees including older workers who may have been displaced from their previous employment. There are additional serious implications for younger workers, especially women, who will have increasing responsibilities to care for aging parents. This may be especially true here in Arkansas where the poverty rates are among the highest in the nation. For single Hispanic and African American women over the age of 65, the poverty rate is 40.8% and 30.7% respectively. Paid caregivers are not a possibility for these older women so their care falls back on family members, typically women, or the State. One study found more than half, 52%, of women making below $35,000 spent more than 20 hours per week providing care to an elderly person--often a relative. https://www.caregiver.org/women-and-caregiving-facts-and-figures. Many of these workers have traditionally worked in the food and food service industries.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Clark, J. and Crandall, P.G. 2019. Educational Affordances of Google Glass as a New Instructional Platform for Foodservice Training," Journal of Foodservice Management and Education. Vol 13(1) 28-32. Published jointly by the Foodservice Systems Management Educational Council and the National Association of College & University Food Service http://fsmec.org/journal/
Clark, J.A., Crandall. P.G., Pellegrino, R. and Shabatura, J.C.. 2019. Assessing Smart Glasses-Based Foodservice Training: An Embodied Learning Theory Approach. �valuation dune formation en service alimentaire bas�e sur des lunettes intelligentes. Canadian Journal of Learning & Technology 45 (2). DOI: https://doi.org/10.21432/cjlt27838
Clark, J. A., Crandall, P.G., and Reynolds, J. (2019). Exploring the influence of food safety climate indicators on handwashing practices of restaurant food handlers. International Journal of Hospitality Management, 77, 187-194.
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Progress 10/01/17 to 09/30/18
Outputs
Target Audience:Food processors in Arkansas, nationally and internationally Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?There are 3 PhD students and 3 MS student working on various aspects of this research How have the results been disseminated to communities of interest?Results have been presented at national meetings and published in the peer-reviewed literature. What do you plan to do during the next reporting period to accomplish the goals?I am continuing to work with the campus-wide group. We will be meeting next week to plan our next round of funding. I've talked with several managers from our stakeholders about the "graying" of the food manufacturing and food service work force. I plan to lead a University charge to play a leadership role in proposing accommodations and adaptations needed by older workers. In addition to this exploratory research, I am very involved in each of my graduate students' research programs.
Impacts
What was accomplished under these goals?
If we understand this is an enormous problem in the nations' public health what are we doing about it? In a nutshell, "people make people sick". It is as plain as that. We may have been researching the easy topic--we have focused almost all of these research dollars on finding out more about the basic mechanisms. Granting agencies continue to pour money into basic research on infection when the attribution data clearly shows that more than half (61%) of the food borne illness outbakes can be traced back to poor employees' personal hygiene and improper food handling by employees in the foodservice industry. And while conventional training and preventive actions continue to be carried out, they appear to be less and less effective when correlated with decreases in the reported food outbreaks over the same period. We need to leverage the enormous amount of knowledge in adult learning theories and adapt those theories to make improvements in our food handlers' long-term behavior. First, we have conducted research on new technologies, such as augmented reality headsets or head-mounted action cameras, that could transform the way food safety training is conducted. Training conducted with wearable technology presents visual content in the first person or actor's perspective, as opposed to the traditional third-person or observer perspective. This visual hands-on first-person perspective may provide a more effective way of conveying information and encouraging behavior execution because it uses the mirror neuron system. There is little published literature about the impact of perspective on food safety training outcomes, such as motivation. This study included a repeated-measures design to determine how first- and third-person camera angles affected hand washing training reactions among 108 currently employed restaurant food handlers. Participants were assessed on their post training compliance intentions, compliance self-efficacy, perceived utility of the training, overall satisfaction with the training, and video perspective preference. A significant proportion of food handlers (64%) preferred the first-person video perspective and a significant correlation was found between compliance intentions and compliance self-efficacy for the first-person video. Second, Recent adult learning models have conceptualized food safety climate as the shared values and perceptions of employees. The present study sought to understand how food safety climate indicators including commitment, role overload, and contingent rewards affect handwashing frequency of restaurant food handlers. In a separate study with more than 100 restaurant employees, the commitment of the manager was the only variable significantly positively correlated with handwashing frequency. A multiple regression model showed managerial commitment was a significant predictor of handwashing frequency. The employees' role overload moderated the relationship between goal level and handwashing frequency, but only when role overload was low, suggesting the presence of competing subcultures. Managers should prioritize a food safety culture and structure jobs in such a way that promotes proper food safety behavior execution. Finally, proper handwashing is a simple, cost effective means for reducing the risk of foodborne disease transmission. Low compliance rates are often observed among food handlers, and a wide range of interventions have attempted to increase compliance, often with little success. Promoting lasting behavior change is difficult, and theoretical models like the Intervention Ladder developed by the Nuffield Council on Bioethics function as useful paradigms to help guide and promote behavior change. While the Intervention Ladder was developed to address issues like infectious disease, obesity, and drug use, it is applicable to the food industry with regards to promoting food safety practices like handwashing. The aim of this review was to expand on the Intervention Ladder and describe its application in the food industry. We believe the Intervention Ladder can serve as a model to benefit food industry stakeholders through providing strategies to promote handwashing compliance. We have modified the original model to include various levels of employee freedom that might impact which strategy is most appropriate depending on the circumstances. Limitations for each strategy are also considered as aredirections for future research. Who has been impacted? Arkansas' of 3 million persons is roughly 1% of the US population of 326 million. The current impact of food borne illness means that every year, a man, a woman and a child dies needlessly because of something they ate. Even though there are numerous contributing factor--proper employee hygiene, executed as a habit could help save the lives of 1 or 2 Arkansas' each year. That would certainly be a life saving impact from our research.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Clark J, Crandall PG*, OBryan CA. 2018. Climbing the intervention ladder to handwashing compliance: a review and directions for future research. Food Control. 84:544-551. DOI: 10.1016/j.foodcont.2017.09.009 Published on line Feb. 2018. Five year Impact Factor 3.891.
Clark J, Crandall PG* and Shabatura JC. 2018. Wearable Technology Effects on Training Outcomes of Restaurant Food Handlers. Journal of Food Protection, Vol. 81, No. 8, 2018, Pages 12201226. doi:10.4315/0362-028X.JFP-18-033. 2017 Impact Factor 1.510.
Clark J, Crandall PG, and Reynolds J. 2018. Exploring the influence of food safety climate indicators on handwashing practices of restaurant food handlers. International Journal of Hospitality Management. Pub. On-line 14 July 18. https://doi.org/10.1016/j.ijhm.2018.06.029
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Progress 11/04/16 to 09/30/17
Outputs
Target Audience:Food processors in Arkansas, nationally and Internationally Changes/Problems:This is early in this project so there are no major changes What opportunities for training and professional development has the project provided?Three PhD students and 5 MS students are working under my direction on various aspects of these projects How have the results been disseminated to communities of interest?These results have been published in peer reviewed jouirnals What do you plan to do during the next reporting period to accomplish the goals?This has been covered extensively in my 2018 Plan of Work
Impacts
What was accomplished under these goals?
Food safety continues to be a major concern with consumers, retailers, food manufacturers and regulators. The estimates vary but human error, largely because of inadequate training is the single most important factor causing food borne illness outbreaks. Objective 1: Survey food processors world-wide to determine how effecting the Global Food Safety Initiative has been in improving employee training and reducing the burden of food borne illness. The Global Food Safety Initiative (GFSI) was developed in the year 2000 following several high-profile foodborne illness outbreaks which caused consumer confidence in our food supply to drop to an all-time low. Since then, 15,000 international food and beverage manufacturing companies have become compliant with one of the GFSI benchmarked standards for food safety. The daily management of GFSI is under the direction of The Consumer Goods Forum (CGF), a global network of nearly 400 of the world's largest consumer goods retailers and their manufacturers from 150 countries. We were asked by the management of GFSI to initiate a research study at the global, CGF level, to determine how successful GFSI has been in meeting the rising food safety expectations around the globe. This multinational assessment determined companies' food safety policies and costs/benefits before and after certification under GFSI. The goal of was to present the most conclusive findings from perhaps the largest international survey that resulted in more than 165,000 responses from more than 800 food manufacturers as to their costs and benefits of becoming compliant with one of the benchmarked GFSI schemes. Overall 87% of these certified suppliers perceived GFSI as being beneficial or very beneficial to addressing their food safety concerns. Nearly three-quarters (72%) of these food manufacturers would choose to go through the certification process again even if certification were not required by one of their current retail customers. Important drivers for becoming GFSI certified included continuing to do business with an existing customer, starting to do business with new customer, reducing the number of third party food safety audits and continued improvement of their food safety program. A majority of manufacturers agreed that GFSI had enhanced their ability to produce safe food and 52% of the respondents saw increases in their sales and revenues in the year following certification. A majority of respondents (81%) agreed that there was a substantial investment in staff time since certification and 50% agreed there was a significant capital investment. We believe this is the largest and best representative survey of global food manufacturers conducted to date. Objective 2. With the passage of the Food Safety Modernization Act (FSMA) food manufacturers are now required by law to have a modern, up-to-date product recall plan in place. A food safety recall can be life threatening to consumers and is a major expense for the food processor involved. Product recalls in particular can be a costly part of managing a food safety event. A report by a major insurance company, the Swiss Reinsurance Company, estimated that in more than half their recalls, the cost was cost upwards of $10 million. Costs of recalls involving products that are already in national distribution can reach as much as $100 million. Overall cost of recalls can be much larger in the long-term because consumers may continue to avoid a product that has been associated with foodborne illness long after the recall has ended. This leads to a potentially significant drop in future profits for the manufacturer, in addition to the excessive costs associated with the recall alone. Our review of the literature resulted in a publication that became the cover story in the May June Food Protection Trends. We described that food manufacturers want to avoid required or voluntary market recalls of their products. Recalls are costly and time consuming and can destroy a company's image or force it into liquidation. Despite an initial expense, the installation of a robust market withdrawal system could significantly reduce the overall costs of a recall. A withdrawal system that is routinely tested allows the manufacturer to quickly identify the implicated products' location in the marketing chain and permits immediate quarantine of the suspect product from the market before it reaches retail distribution. Thus, a well-rehearsed market withdrawal would reduce the major costs of damage to manufactures' reputations and reimbursements to consumers. Objective 3. Could it be that the Gold Standard, plate counting, for enumerating pathogenic bacteria from food could be under reporting viable pathogens? Listeria monocytogenes (LM) is a foodborne pathogen which is found in rural environments and frequently in raw products used in food production. The compromised immune systems of infants, the elderly and pregnant women make them especially vulnerable to infection by LM. In the food production environment, LM is frequently isolated from niches such as floor drains, cart wheels, shoes, and many other areas. Other locations may not support the growth of the pathogen but might still protect viable LM cells. If these cells survive under these low nutrient or starvation conditions, they may later be dislodged and contaminate food products or be deposited where nutrients are more plentiful. When many species of bacteria that are normally easily grown are starved for long periods of time, the culturable cell count declines while the total cell count as measured by microscopy or turbidity may remain constant, leading to a large number of non-culturable cells. Culture based methods presume that these cells are dead. However, some researchers have advanced a theory which hypothesizes that the non-culturable cells are in a "viable but non-culturable" (VBNC) state in which they remain viable but cannot be cultured. There is sharp disagreement between proponents and critics of the VBNC hypothesis. Nevertheless, various approaches for assessing the cells' viability have been used, usually involving labelling methods for direct querying of the cells to indicate viability but not whether or not the cell is capable of growing or dividing. Demonstrating viability usually attempts to measure gene expression, protein synthesis, energy production, maintenance of membrane integrity, and/or enlargement of the cell. Some experimenters have attempted to induce the presumably VBNC cells to recover and begin division again, but these experiments can be confounded if even a few culturable cells are mixed into a population of presumptive VBNC cells; these few cells will multiply and give the appearance of regrowth of VBNC cells. LM strains EGD-e, Scott A, F2365, and HCC23 were starved individually in sterile water. Colony counts declined over 4 weeks, with Scott A declining the most rapidly. Transmission electron microscopy images show degradation of starving cell membranes and altered cytosols. Starving cells were subjected to the metabolic inhibitors fluoride, arsenite, 2,4-dinitrophenol (DNP), iodoacetate, and cyanide individually. Iodoacetate, which inhibits glyceraldehyde-3-phosphate dehydrogenase, completely reduced cultivable counts below the level of detection as compared to the control starving cells; DNP, which dissipates proton motive force, almost completely reduced cultivable counts. These results suggest that LM strains EGD-e, Scott A, F2365, and HCC23 are actively using part of glycolysis pathway while starving. These results suggest that starving LM retain aspects of active metabolism.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Crandall PG*, Mauromoustakos A, O'Bryan CA, Thompson KC, Yiannas F, Bridges K, Francois C. 2017. Impact of the Global Food Safety Initiative on Food Safety World-Wide: Results of a Survey of International Food Processors. J Food Prot. 2017 Oct;80(10):1613-1622. doi: 10.4315/0362-028X.JFP-16-481.
Jarvis NA, O'Bryan CA, Martin EM, Ricke SC, Johnson MG, Crandall PG*. 2017. Further Evidence of How Unbuffered Starvation at 4�C Influences Listeria monocytogenes EGD-e, HCC23, F2365, and Scott A. J Food Prot. 2017 Oct;80(10):1749-1759. doi: 10.4315/0362-028X.JFP-17-041.
Jarvis NA, Donaldson JR, O'Bryan CA, Ricke SC, Crandall PG*. 2017. Listeria monocytogenes infection of HD11, chicken macrophage-like cells. Poult Sci. 96(4):950-956. doi: 10.3382/ps/pew358.
Weaver TL, Crandall PG*, OBryan CA, Thomsen MR. 2017. A robust market withdrawal system can reduce your product recall costs. Food Protection Trends 37:3 Pages 154-160.
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