Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail...
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Transcript of Régis POUILLOT, DVM, PhD FDA/CFSAN Draft - Interagency Listeria monocytogenes in Retail...
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 22nd, 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…
-3 -2 -1 0 1 2 3
0.98
50.
990
0.99
51.
000
log10(Lm concentration, MPN/g)
Cum
ulat
ive
Fra
ctio
n
retail slicedprepackaged
(Draughon, 2006)
???
2May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline
• Design
• Data Sources
• Implementation
• Modeling Approach
• Verification
3May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
The Retail Deli Area
FoodMeatCheeseSalad
Food workersBehavior Events
SitesSlicersCasesFood Contact SurfacesNon Food Contact SurfacesUtensils…
Listeria
NichesSlicersCases…
4May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Example Serve Customer Event
5May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Example: Serve Customer Event
Wipe Slicer
Removes some bacteria from the slicer (if any)
6May 22nd, 2013Interagency 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
7May 22nd, 2013Interagency 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
8May 22nd, 2013Interagency 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 9May 22nd, 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
10May 22nd, 2013Interagency 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
11May 22nd, 2013Interagency 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
12May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Example: Non Deli Time Event
Bacterial growth on products
13May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
14 14May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
From Retail to Risk
Dose Response ModelDose Response Model
Probability of IllnessProbability of Illness
Contamination when soldContamination when sold
Contamination when eatenContamination when eaten
Home Storage (bacterial growth)Home Storage (bacterial growth)
0 2 4 6 8 10 12
-12
-10
-8-6
-4-2
0
log10dose
log
10P
robi
llnes
s
Serving SizeServing Size
Number of Lm ingestedNumber of Lm ingested
(FAO/WHO, 2004)
15May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline
• Design
• Data Sources
• Implementation
• Modeling Approach
• Verification
16May 22nd, 2013Interagency 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): 1139-56
Transfer coefficients and Slicer– Meta analysis of literature data (In-house study) – Hoelzer K, et al. (2012) International J of Food Microbiology, 157:267-77.
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): 272-82
Food worker behavior– Observational study (FDA JIFSAN UMD collaboration)– Lubran MB, et al. (2010) J Food Protection, 73 (10):1849-57.
17May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Lubran MB, et al. (2010) J Food Protection, 73 (10):1849-57
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
Process Objects Involved
Bacteria inactivation hands
Cross contamination Case - glove
Cross contamination Case - glove
Cross contamination
PartitioningCross contamination
Chub – product sold1st slice – glove
Cross contamination Scale - glove
18May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Additional Data/Model
• Growth model– Mejholm and Dalgaard, 2009 J Food Prot, 72(10), 2132-2143.
• Temperature in deli case– Ecosure 2007 data (www.FoodRisk .org)
• Time and temperature during transport and at home– Ecosure 2007 data (www.FoodRisk .org)
• Consumption data– NHANES study, WWEIA data, 1999-2006
• Dose response model– FAO/WHO 2004
190 5 10
2
4
6
8
time (weeks)
0 5 10 15 200
2
4
6
8
10
time (days)
0
2
4
6
8
10
0 20 40 60 80 0 10 20 30 400
2
4
6
8
10
log 1
0 u
fc.m
l-1lo
g 10
ufc
.ml-1
log 1
0 u
fc.m
l-1
(e)
(g) (h)
(i)
time (days) time (days)
5.5°C 8.5°C
0 20 40 60 80-2
0
2
4
6(f)
time (weeks)
May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline
• Design
• Data Sources
• Implementation
• Modeling Approach
• Verification
20May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
R model
“Blue Meadow” cluster2,016 cores, 21 TFlops
Available through the Office of Science and Engineering Laboratories, CDRH - FDA
Parallel computing
ParametersExcel 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
Transfers: log10(T0.Baseline + 1)
To
Fro
m
Mea
tCheese
Salad
HandGlov
eFloo
rSink
Handle
Scale
CaseUtensil
Utensil
Handle
Slicer
FCSNFCSSold
Niche
RawFoodGro
wth
Mea
t
Cheese
Salad
Hand
Glove
Floor
Sink
Handle
Scale
Case
Utensil
Utensil
Handle
Slicer
FCS
NFCSSold
Wash
ed
Trash
0
2
4
6
8
10
12
14
Outputs
21May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline
• Design
• Data Sources
• Implementation
• Modeling Approach
• Verification
22May 22nd, 2013Interagency 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
23May 22nd, 2013Interagency 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
24May 22nd, 2013Interagency 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
25May 22nd, 2013Interagency 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?
26May 22nd, 2013Interagency 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
27May 22nd, 2013Interagency 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
28May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline
• Design
• Data Sources
• Implementation
• Modeling Approach
• Verification
29May 22nd, 2013Interagency 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)
30May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting