Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail Delicatessens Risk Assessment Part 1: Design - Data Sources – Modeling Approach Interagency Risk Assessment - L. monocytogenes in Retail Delicatessens Public Meeting Washington, DC - May 22 nd, 2013

(recall) Objectives of the Model Fact: higher prevalence and level of Listeria monocytogenes in products that are sliced at retail vs. sliced by manufacturer Hypothesis: at retail –Additional cross-contaminations? –Temperature abuses? Charge: –“What are the key processes that lead to additional Listeria monocytogenes contamination / higher levels at retail?” –“How much is the relative risk/serving reduced according to specific risk management options?” A model… (Draughon, 2006) ??? 2 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Outline Design Data Sources Implementation Modeling Approach Verification 3 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

The Retail Deli Area Food Meat Cheese Salad Food workers Behavior  Events Sites Slicers Cases Food Contact Surfaces Non Food Contact Surfaces Utensils … Listeria Niches Slicers Cases … 4 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Example Serve Customer Event 5 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Example: Serve Customer Event Wipe Slicer Removes some bacteria from the slicer (if any) 6 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Example: Serve Customer Event Wipe Slicer Wash hands & change gloves Removes some bacteria from hands (if any). No bacteria on the gloves 7 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Example: Serve Customer Event Wipe Slicer Wash hands & change gloves Potential cross contamination between gloves and case Open case, remove chub, close case 8 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Example: Serve Customer Event Wipe Slicer Wash hands & change gloves Open case, remove chub, close case Slice on gloves Potential cross contamination among gloves, slicer, chub and potential contamination of the product sold 9 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

10 Example: Serve Customer Event Wipe Slicer Wash hands & change gloves Open case, remove chub, close case Slice on gloves Touch scale Potential cross contamination between gloves and scale 10 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

11 Example: Serve Customer Event Wipe Slicer Wash hands & change gloves Open case, remove chub, close case Slice on gloves Touch scale Rewrap chub Potential cross contamination between the chub and the food contact surface 11 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

12 Example: Serve Customer Event Wipe Slicer Wash hands & change gloves Open case, remove chub, close case Slice on gloves Touch scale Rewrap chub Potential cross contamination between the gloves and the case Open case, replace chub, close case 12 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Example: Non Deli Time Event Bacterial growth on products 13 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

14 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

From Retail to Risk Dose Response Model Probability of Illness Contamination when sold Contamination when eaten Home Storage (bacterial growth) Serving Size Number of Lm ingested (FAO/WHO, 2004) 15 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Outline Design Data Sources Implementation Modeling Approach Verification 16 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Studies Undertaken to Collect Data Risk mapping –Expert opinion to validate where Lm occurs, what transfers likely (FSIS Contract) –Hoelzer K, et al. (2012) Risk analysis, 32(7): Transfer coefficients and Slicer –Meta analysis of literature data (In-house study) –Hoelzer K, et al. (2012) International J of Food Microbiology, 157: Persistent strains in deli departments –Longitudinal study, Cornell University (FSIS Contract) –Manuscript in preparation Potential transfer during specific events –Mock deli using GloGerm, Virginia Tech (FSIS Contract) –Maitland J, et al. (2013) J Food Protection, 76 (2): Food worker behavior –Observational study (FDA JIFSAN UMD collaboration) –Lubran MB, et al. (2010) J Food Protection, 73 (10): May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Lubran MB, et al. (2010) J Food Protection, 73 (10): Example #1: Which Sites? Which Events? Observational study in retail environment Action No. Action Sequence 1. 10am Wash hands 2.Put on gloves 3.Open case 4.Pick up salami 5.Close case 6.Put salami on slicer 7.Slice salami on gloves 8.Put salami on tissue 9.Touch scale 10.Give bag to customer ProcessObjects Involved Bacteria inactivationhands Cross contaminationCase - glove Cross contaminationCase - glove Cross contamination Partitioning Cross contamination Chub – product sold 1 st slice – glove Cross contaminationScale - glove 18 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Additional Data/Model Growth model –Mejholm and Dalgaard, 2009 J Food Prot, 72(10), Temperature in deli case –Ecosure 2007 data ( Time and temperature during transport and at home –Ecosure 2007 data ( Consumption data –NHANES study, WWEIA data, Dose response model –FAO/WHO May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Outline Design Data Sources Implementation Modeling Approach Verification 20 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

R model “Blue Meadow” cluster 2,016 cores, 21 TFlops Available through the Office of Science and Engineering Laboratories, CDRH - FDA Parallel computing Parameters Excel Data File A Technical Challenge… Discrete Event model + Few bacteria in the system = Slow convergence Each simulation: 100 Stores; 1,000,000 Servings Currently: 126 Scenarios Outputs 21 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Outline Design Data Sources Implementation Modeling Approach Verification 22 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Long term data gaps Sources of Listeria monocytogenes –Acquired data: frequency of contamination of NFCS –Data needs: better quantification: Relative contribution incoming food vs. environment? Transfer events –Acquired data: better qualifications of NFCS interactions (drains, sinks,…). –Data needs: better quantification Frequency of occurrence of transfers in deli settings Number of bacteria transferred per transfer. Niches –Acquired data: better quantification on the frequency of occurrence –Data needs: better quantification Frequency of transfer to FCS Number of bacteria transferred 23 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Because of the data gaps on the relative impact of environmental contamination vs. contamination from products, we evaluated a range of retail delicatessens conditions Approach –Define some baseline conditions Baseline #1: regular environmental contaminations occur in the stores Baseline #2: no environmental contamination occurs in stores … –Evaluate various scenarios within these baseline conditions Modeling Approach 24 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

#1: “Multiple Niche 100W” baseline condition Stores with regular L. monocytogenes transfer from the environment and/or niches Incoming L. monocytogenes : from incoming products and from the environment/niche #2: “No Niche” baseline condition Stores without transfer from the environment and/or niche Incoming L. monocytogenes : from incoming products #3: “Incoming Growth Chub” baseline condition Stores with highly contaminated incoming product type that supports growth #4: “Incoming Non-Growth Chub” baseline condition Stores with highly contaminated incoming product type that does not support growth #5: “Temperature Control” baseline condition Stores without transfer from the environment and/or niche and with compliant temperature control (  41°F) #6: “Niche & Temperature Control” baseline condition Stores with regular L. monocytogenes transfer from the environment and/or niches and with compliant temperature control (  41°F) Step 1: Definition of Baseline Conditions 25 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Step 2: Evaluation of the impact of various mitigation strategies in these contexts Within each of the 6 Baseline conditions –22 Scenarios Answer the question (example): –Given that there is a niche in a retail deli, what are the best mitigation strategies? and not –What is the probability that there is a niche in the store? 26 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Approach to Risk Management Questions Separate slicers / counters for growth versus non growth products? –Model more than one slicer. Select slicer to use each time customer is served based on product type. What is the impact of the use of “gloves” in the retail environment? –Set probability of wearing gloves to 100% Consider frequently touched non-food contact surfaces (e.g. case handles, scale touch pads) as food contact surfaces (i.e., required to be cleaned and sanitized every four hours)? –Change site classification to FCS  Flexibility of the Discrete Event Model 27 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

“What-If” Scenarios Sanitation Related Scenarios –Some NFCS cleaned FCS, Increase the effectiveness of cleaning, No sanitation, … Worker Behavior Related Scenarios –No glove, No contact glove-case, Preslice products in the morning, Do not slice product on gloves Growth Inhibitor Related Scenarios –All products with GI, No product with GI Cross contamination Related Scenarios –Separate slicers, No cross contamination Storage Temperature and Duration Related Scenarios –Temperature in compliance with FDA food code, Temperature set so that no growth can occur 28 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Outline Design Data Sources Implementation Modeling Approach Verification 29 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Verifications 30 General correspondence between the frequency of contamination vs. observed one (Cornell longitudinal study) Important sources of contamination considered in the model (Risk mapping, Mock Deli study) Control of the mass balance Correspondence between the simulated bacterial density distribution vs. the observed one (NAFSS, 2008) (this graph) 30 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting