Progress 01/01/17 to 12/31/17
Outputs
Target Audience:The data from this study will be useful to retail grocery food safety experts, state and federal food safety experts, and future risk assessments. Changes/Problems:The initial sampling of >10,000 environmental samples cost more than was previously expected- mostly due to the enormous amount of enrichment media necessary for pathogen detection. As a result, I have sacrificed my salary line for the second year of the project in order to continue towards our goal of WGS based subtyping. What opportunities for training and professional development has the project provided?Two graduate students have joined my lab to assist on this project; one who is focusing more on the logistics, sampling and subtyping portions and another who is focusing more on the survey and statistical correlation aspect. Though they are assigned separate focuses, this initial data gathering period is a joint effort and has allowed overlap in discussion and strategy which is beneficial for both of the graduate students. Both graduate students have submitted an abstract based on the data currently available to the 2017 IAFP Annual Meeting- this will develop their skills in scientific communication. One of the students was able to attend the annual 2016 IAFP meeting as a graduate mentor for an undergraduate trip. This experience not only allowed the student networking and professional interfacing, but allowed him to attend several presentations. Most of talks he attended were in relation to Whole Genome Sequencing analysis and applications in the food industry, which provided invaluable insight and opinions regarding the eventual sequencing and sequence analysis of the obtained isolates. Additionally, four undergraduate students have obtained lab experience by helping on this project. One of these students was a paid summer employee, while the other three have been working in the lab for credit. Their duties and knowledge gained has depended largely on their own motivation. All students have learned the basics of working in a lab, and some have spent extra hours and learned additional skills. One student has begun his senior thesis based on the APC of several of the collected samples. This undergraduate was also able to submit and abstract for the IAFP 2017 Annual Meeting based on data collected from this study. How have the results been disseminated to communities of interest?Two papers will besubmitted a; SNP-based whole genome subtyping of L. monocytogenessamples is currently taking place which will allow re-submission of the publications. Three poster presentations were used to disseminate the information at the IAFP 2017 Conference. What do you plan to do during the next reporting period to accomplish the goals?We will complete the subtyping ofL. monocytogenesisolates. Data from Objective III has just begun to be analyzed. Further analysis will take place which will allow us to draw conclusions with a statistical backing.
Impacts
What was accomplished under these goals?
The accomplishments surrounding Objectives I and II have been reported in previous reporting periods and have not changed significantly since. For the purpose of brevity, we will present our new accomplishments. This is true with one exception. A second comprehensive survey was sent out to the stores participating in the interventions described below. This would fall under Objective II; the data is currently being collected. OBJECTIVE III Based on the results of the sampling in Objective I, nine stores which presented the largest challenge for control of L. monocytogenes were enrolled in the intervention phase of this study. These stores made up nine of the ten stores with the high prevalence of L. monocytogenes. Additionally, a store which had only 2/159 positive samples for L. monocytogenes was chosen to continue sampling without any interventions to serve as a control. The nine stores can be divided based on either retailer or independent regional management within a retailer; four groups in four different states. We partnered with the chemical supply company for three of those groups to reduce costs and increase intervention and monitoring feasibility. Regardless of group, the goal was for each individual store to undergo a deep clean performed by the department's employees with supervision and support from their managers and the researchers. The deep cleans were performed in concert with an explanation of the study's data to the employees which included an introduction to L. monocytogenes and the importance of ensuring that the pathogen can't re-establish itself. Predetermined SSOP changes were also explained. Employee participation varied largely by store and group. Foam squeegees were discarded and replaced with rubber squeegees. Following the deep cleans a two-month wash-in period for SSOP changes was allowed prior to sampling. Each store was audited bi-weekly by either corporate food safety or regional representatives of our partner chemical supplier. Many sites which were sampled during the initial sampling were eliminated from follow-up sampling. Due to the very high amount of L. monocytogenes positive samples relating to the floor, an additional five sampling sites were added to tease out potential harborage sites; cart wheels, underside of stability mats, interior of dustpan, surface of produce storage pallets, and the nozzle of the spray hose. Finally, after each month, reactionary steps were taken to address any positive samples. Samples were collected by regional food safety employees under direction from our research group and shipped overnight, on ice, for processing at Purdue University. The Roka Bioscience Atlas platform's LmG2 assay was used to detect positive samples, which were subsequently confirmed by secondary enrichment and plating. Up to four colonies from each site were stored in 20% glycerol at-80O Celsius for future analysis. The sites with the most positive samples were similar to those in the initial sampling period. Standing water, once again, had the highest prevalence of L. monocytogenes with 41.7% (10/24) samples positive. This was followed by the drain (38.1%; 8/21) and floor (37.5%; 3/8) of the cold room. The drain of the produce preparation area had 34.5% (10/29) of its samples positive. Interestingly, one of the added sites, interior of the dustpans, had 32.1% (9/28) positive; larger than the squeegee which had 27.6% (8/29) positives. When looking at individual store improvement we compared only the sites which were sampled in both the initial and follow up sampling. Group 1, which contains only store 14, showed the most promising results. The prevalence of L. monocytogenes decreased from 53.3% (16/30) to 5.6% (1/18). The results of Group 2 were also encouraging. Store 27 decreased from 63.3% (19/30) to 26.7% (4/15); store 5 decreased from 60.0% (18/30) to 33.3% (5/15); and store 22 from 20.0% (6/30) to 13.3% (2/15). The stores in Group 3 both had a moderate increase in prevalence on these sites; store 8 increased from 20.0% (6/30) to 33.3% (5/15) and store 21 from 16.7% (5/30) to 40.0% (6/15). It should be noted that there appeared to be decrease in positive samples each month with both Group 2 and Group 3. That will be analyzed for statistical significance. Group 4 contained store 28, the store with the highest overall prevalence in the initial sampling, and store 17. Neither store performed well; store 28 decreased insignificantly from 93.3% (28/30) to 86.7% (13/15). Store 17 experience no change staying flat at 40.0% (12/30; 6/15).
Publications
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2018
Citation:
John Burnett, Deklin Veenhuizen, Tongyu Wu, Susan R. Hammons, Manpreet Singha, and Haley F. Oliver. Submitted.
Listeria monocytogenes is Prevalent in Retail Produce Environments but Salmonella enterica is Rare. Appl. Environ.
Micrbiol.
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2018
Citation:
Tongyu Wu, John Burnett, Jingjin Wang, Susan R. Hammons, Deklin R. Veenhuizen, and Haley F. Oliver. Submitted.
Infrastructure, sanitation, and management practices impact Listeria monocytogenes prevalence in retail grocery produce
environments. J Food Prot.
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Progress 01/01/16 to 12/31/16
Outputs
Target Audience:Retail food safety experts, USDA risk assessment, academics, and others interested in produce food safety. Changes/Problems:Primarily, we were not able to bring in a student to focus solely on this project until the beginning of June, which pushed back the start date for sampling to June. We have found that retail produce envronemnts are likely not a significant source of produce contamination by S. enterica because the organism does not seem to establish niches in the environment. For that reason, we will not be testing for its presence in the second longitudinal sampling phase and will focus our resources on sequencing isolates. What opportunities for training and professional development has the project provided?Two graduate students have joined my lab to assist on this project; one who is focusing more on the logistics, sampling and subtyping portions and another who is focusing more on the survey and statistical correlation aspect. Though they are assigned separate focuses, this initial data gathering period is a joint effort and has allowed overlap in discussion and strategy which is beneficial for both of the graduate students. Both graduate students have submitted an abstract based on the data currently available to the 2017 IAFP Annual Meeting- this will develop their skills in scientific communication. One of the students was able to attend the annual 2016 IAFP meeting as a graduate mentor for an undergraduate trip. This experience not only allowed the student networking and professional interfacing, but allowed him to attend several presentations. Most of talks he attended were in relation to Whole Genome Sequencing analysis and applications in the food industry, which provided invaluable insight and opinions regarding the eventual sequencing and sequence analysis of the obtained isolates. Additionally, four undergraduate students have obtained lab experience by helping on this project. One of these students was a paid summer employee, while the other three have been working in the lab for credit. Their duties and knowledge gained has depended largely on their own motivation. All students have learned the basics of working in a lab, and some have spent extra hours and learned additional skills. One student has begun his senior thesis based on the APC of several of the collected samples. This undergraduate was also able to submit and abstract for the IAFP 2017 Annual Meeting based on data collected from this study. How have the results been disseminated to communities of interest?Publications have been sumbitted for publication. What do you plan to do during the next reporting period to accomplish the goals?Complete Objective 3 and sequenceL. monocytogenesisolates
Impacts
What was accomplished under these goals?
Thirty environmental samples were collected monthly for six months in duplicate in 30 retail produce departments in seven states during daily operation. Samples included 17 food contact surfaces and 13 non-food contact surfaces. Each sample was tested for L. monocytogenes and S. enterica using ROKA Atlas LmG2 and SEN assays, respectively. Positive L. monocytogenes enrichments were confirmed by secondary enrichment in Fraser broth and plating; positive S. enterica enrichments were confirmed using the standard FDA BAM protocol. A total of 4.4% (226/5112) of environmental samples tested positive for L. monocytogenes; L. monocytogenes was present on 8.1% (178/2205) non-food contact surfaces (NFCS) and 1.6% (48/2907) of food contact surfaces (FCS) tested. S. enterica was found during one sampling event in a single store; <0.1% (4/5112) of samples were positive overall. Defining high prevalence as >10%, low prevalence as <1% and moderate prevalence as between 10% and 1% (Simmons et al., 2014), 7 of 30 stores showed low overall L. monocytogenes prevalence across all sites, including five stores with no positive samples. Four of 30 stores had high overall prevalence at levels of 24.4% (43/176), 14.5% (25/172), 13.4% (23/172) and 10.5% (17/162). Of the remaining 19 stores only six showed a prevalence of >5%, ranging from 5.6% to 9.6%. Nine of 20 stores showed high L. monocytogenes prevalence on NFCS, ranging from 41.9% (31/74) to 10% (7/70). Seven stores had low prevalence on NFCS, all of which didn't have any positive samples. Of the 14 stores with moderate prevalence on NFCS only three had a prevalence of >5%. Conversely, only one store displayed high prevalence on FCS with 11.8% (12/102) samples positive. This store, number 28, also displayed the highest NFCS prevalence and overall prevalence. For low prevalence, 14 stores tested positive for less than 1% of samples, including 11 with no positive samples. Of the remaining 15 stores, only one displayed a prevalence of >3.4% with 7.4% (7/94) of its samples positive. Seven stores exhibit possible evidence of L. monocytogenes environmental persistence, with at least three consecutive months positive on the sample sampling site. Susceptible sites for L. monocytogenes harborage include the cold room drain, with 36.0% (27/75) samples testing positive. The cold room floor, which was sampled in the absence of a drain had 13.2% (14/106) positives. Standing water exhibited the second highest prevalence at 27.7% (46/166), 12 of which were located in corners of a room, in damaged or recessed floor areas, or on utility covers. 13 were in the cold room, and only three were under/near sinks. The drain of the general produce area had 20.2% (33/163) of samples positive while the floor, in the absence of a drain, returned no positives with 17 samples taken. The squeegee or other floor cleaners revealed themselves as a high prevalence site with 18.3% (33/180) samples positive. In the absence of a squeegee, other sites were sampled. Three of the 33 positives were samples taken from brooms, the remaining 30 were all taken from foam squeegees. All in all, 21.7% (30/138) of squeegees tested positive for L. monocytogenes and 16.2% of brooms (3/22). Finally, a temporal analysis of this longitudinal study showed that in the sampling events in August and early September had a statistically significant increase in the number of positive samples. However, it can be fairly argued that this uptick was the result of a spike in only a few stores, with the other stores continuing their previous patterns. The above data indicates that L. monocytogenes is a critical pathogen associated with retail produce environments, largely present and able to establish persistence in NFCS such as drains, floor, standing water and squeegee. To achieve Objective II, we have proposed and distributed a survey on facility designs, management strategies, and cleaning and sanitizing practices in retail produce environment. The intended participants are produce managers. A pilot study was performed in mid-September in 5 stores that are not sampled. The revised survey consists of 110 multiple choice and short answer questions, which takes thirty minutes to one hour to complete. The survey was then distributed among the 30 stores that are currently being sampled via Qualtrics. All surveys have been completed and linear regression analysis was being performed to see the statistical significance of: 1) facility designs, 2) management strategies, 3) cleaning and sanitation practices, correlating with L. monocytogenes prevalence pattern obtained from Object I. Specifically, Pearson correlation was used for analyzing continuous and ordinal variables; one-way ANOVA and Tukey pair-wise comparison for categorical variables (α=0.05). To further visualize the correlation between L. monocytogenes prevalence and statistically significant categorical variables, cross tabulation was performed, with prevalence level categorized into "low" (<1%), "moderate" (1-10%) and "high" (>10%) (Simmons et al., 2014; Wang, 2014; Burnett et al., unpublished). Proc Power procedure was performed to assess the adequacy of sample size of this study (α=0.05). Nine factors were significantly associated with L. monocytogenes prevalence. Linear model fit statistics yielded r2=0.5816 and MSE=19.043 with untransformed prevalence data. Linear regression showed that these 9 variables, in synergy, correlating significantly with prevalence (p=0.0171). Yet, no individual factor was consequential. Power analysis showed an over 0.999 power (α=0.05), indicating high confidence in our finding. The survey study has yielded insights and approaches to derive strategies in L. monocytogenes control in retail produce environments. By tackling upon aspects of management strategy, personal hygiene, preventing cross-contamination, cleaning and sanitation frequencies, our study yields feasible suggestions to retail produce managers to prevent L. monocytogenes transmission in retail system. Specifically, disposing gloves (alternatively, handwashing) after handling each type of produce and after touching NFCS is strongly recommended; selecting lateral role model colleagues among employees can potentially positively cultivating food safety behaviors among the team; accessible and comprehensible SSOPs and their implementation are key to prevent adverse L. monocytogenes spread during cleaning; minimizing inter-departmental traffic; making sure the clean-ability of the produce environment and eliminating pooled and standing water. The intervention is now under implementation in the 30 participating stores. We have the preliminary commitment of the nine stores with the highest prevalence of L. monocytogenes to participate in a second longitudinal sampling to determine the efficacy of any changes to facilities or protocols in controlling L. monocytogenes. We also intend to enroll a tenth store which was absent of any pathogens in our initial sampling period. This store will make no protocol changes and serve as a control.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2017
Citation:
John Burnett, Deklin Veenhuizen, Tongyu Wu, Susan R. Hammons, Manpreet Singha, and Haley F. Oliver. Submitted. Listeria monocytogenes is Prevalent in Retail Produce Environments but Salmonella enterica is Rare. Appl. Environ. Micrbiol.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2017
Citation:
Tongyu Wu, John Burnett, Jingjin Wang, Susan R. Hammons, Deklin R. Veenhuizen, and Haley F. Oliver. Submitted. Infrastructure, sanitation, and management practices impact Listeria monocytogenes prevalence in retail grocery produce environments. J Food Prot.
|