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Risk Mapping and Listeria monocytogenes Transfer in Retail Delis
Karin Hoelzer, PhD
FDA / Cornell University
Interagency Risk Assessment - L. monocytogenes in Retail Delicatessens Public Meeting
Washington, DC - May 22nd, 2013
Goal: Leverage knowledge to prevent cross - contamination
Today’s presentation addresses 4 questions:
1.Which environmental sites are the biggest concern?
2.Likelihood of transfer to food (direct / indirect)?
3.Proportion of bacteria transferred?
4.Efficacy of cleaning / sanitization in removing contamination?
Objective: prevent / minimize environmental cross-contamination
2 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline: Risk mapping & L. monocytogenes transfers
1. Introduction
2. Establishing a risk map of L. monocytogenes in retail delis:
1. Selection of environmental sites & contamination events
2. Expert elicitation of L. monocytogenes transfer dynamics
3. Creating a risk map of L. monocytogenes in retail delis
3. Estimating L. monocytogenes transfer coefficients
4. Estimating the efficacy of cleaning & sanitization
5. Summary & conclusions
3 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Introduction: Listeriosis is a very serious clinical disease
The clinical symptoms:
- Gastroenteritis
- Septicemia
- Meningitis / encephalitis
- Stillbirth / fetal loss
- Other (e.g., joints, skin)
(source: Hoelzer et al., 2012. Vet. Res. 43:18)
4 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Introduction: Cross-contamination at retail is a concern
FSIS risk assessment of L. monocytogenes in deli meats:
Highest risk for retail-sliced deli meats:
- Much greater risk than if pre-packaged
- Growth at retail contributes to risk
- Retail – sliced deli meats account for
~ 70 % of deli-meat associated deaths
(source: Endrikat et al., 2010. JFP 73 (4): 612 - 619)
5 / 25
Introduction: Listeria is common in the retail environment
(source: Hoelzer et al., 2010. JFP 74 (7): 1083 - 1095)
Cross-sectional survey of L. monocytogenes in NY retail delis
L. monocytogenes contamination:
- Extremely common
- Highly variable across establishments
- Most common in non-food contact sites
- Variable across food-contact sites
- Store characteristics some impact
6 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Introduction: Risk maps analyze risks & can guide actionsL
ikel
iho
od
of
occ
urr
ence
Expected impact
High riskImmediate action
Medium riskDetect & monitor
Medium/low riskMonitor
Low riskLow control
Risk = Likelihood of occurrence * expected impact
7 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Introduction: A risk map is useful to focus interventionsP
reva
len
ce o
f co
nta
min
atio
n
Probability of transfer to food
High riskImmediate action
Medium riskDetect & monitor
Medium/low riskMonitor
Low riskLow control
8 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline: Risk mapping & L. monocytogenes transfers
1. Introduction
2. Establishing a risk map of L. monocytogenes in retail delis:
1. Selection of environmental sites & contamination events
2. Expert elicitation of L. monocytogenes transfer dynamics
3. Creating a risk map of L. monocytogenes in retail delis
3. Estimating L. monocytogenes transfer coefficients
4. Estimating the efficacy of cleaning & sanitization
5. Summary & conclusions
9 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Risk mapping: Site selection requires stakeholder input
Source: Hoelzer et al. 2012; Risk Analysis 32 (7): 1139 - 1156
Sites & transfer events included in risk map:
Selection based on:
•Literature review
•Industry experts
•Academic experts
•Regulatory experts (federal, states)
Events: transfer to food / hands / food contact surface
Sites: 31 environmental sites, hands & product
10 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Expert elicitation: Responses differed, but not by employer
Source: Hoelzer et al. 2012; Risk Analysis 32 (7): 1139 - 1156
Study design:
• ‘Delphi’ method
• 45 experts enrolled:
- 20 from retail industry
- 25 from the states
• 2 questionnaires
• telephone conference
11 / 25
Expert elicitation: Hands as cross-contamination vehicles
Source: Hoelzer et al. 2012; Risk Analysis 32 (7): 1139 - 115612 / 25
May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Expert elicitation: Transfer from FCS to product most likely
Source: Hoelzer et al. 2012; Risk Analysis 32 (7): 1139 - 1156
13 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Expert elicitation: Transfer from hand-touch surfaces likely
Source: Hoelzer et al. 2012; Risk Analysis 32 (7): 1139 - 1156
14 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Risk mapping: Risk maps analyze risks & can guide actionsL
ikel
iho
od
of
occ
urr
ence
Expected impact
High riskImmediate action
Medium riskDetect & monitor
Medium/low riskMonitor
Low riskLow control
Risk = Likelihood of occurrence * expected impact15 / 25
May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Risk mapping: FCS’s are the sites of greatest concern
Milk crates
Floor / floor drain
Walk-in cooler
Sink
Produce prep. area
Cart wheelsProduct
Deli case
Utensils
Slicer (1st slice)Slicer (10th slice)
Analyzing the retail deli risk map:
• Based on 2 factors:
- Pathogen prevalence
- Transfer probability
• Considers evidence:
- Amount of data (i.e. bubble size)
- Consent among experts (i.e., legend font size)
16 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline: Risk mapping & L. monocytogenes transfers
1. Introduction
2. Establishing a risk map of L. monocytogenes in retail delis:
1. Selection of environmental sites & contamination events
2. Expert elicitation of L. monocytogenes transfer dynamics
3. Creating a risk map of L. monocytogenes in retail delis
3. Estimating L. monocytogenes transfer coefficients
4. Estimating the efficacy of cleaning & sanitization
5. Summary & conclusions
17 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Transfer coefficients: Transfer efficacy is highly variable
Source: Hoelzer et al. 2012; IJFM 157: 267 - 277
Transfer coefficient findings:
• Some transfers highly efficient
• Some transfers very inefficient
• Transfer efficacy varies by:
- source / recipient sites
- materials
- experimental conditions
- transfer characteristics
- individual replicates
• Widespread contamination with low levels possible
• Need to consider variability
18 / 25 May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Transfers during slicing: Contamination can be widespread
Source: Hoelzer et al. 2012; IJFM 157: 267 - 277
19 / 25
Outline: Risk mapping & L. monocytogenes transfers
1. Introduction
2. Establishing a risk map of L. monocytogenes in retail delis:
1. Selection of environmental sites & contamination events
2. Expert elicitation of L. monocytogenes transfer dynamics
3. Creating a risk map of L. monocytogenes in retail delis
3. Estimating L. monocytogenes transfer coefficients
4. Estimating the efficacy of cleaning & sanitization
5. Summary & conclusions
20 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Cleaning & sanitization: Soiled surfaces are a problem
Modified from: Hoelzer et al. 2012; IJFM 157: 267 - 277
Cleaning and sanitization:
• Sanitizers differ in efficacy
• Ineffective on soiled surfaces
• Efficacy impacted by:
- exposure time
- sanitizer concentration
- inoculum concentration
- individual study
• Efficient removal possible
• Rel. low efficiency possible
• Need to consider variability
21 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Outline: Risk mapping & L. monocytogenes transfers
1. Introduction
2. Establishing a risk map of L. monocytogenes in retail delis:
1. Selection of environmental sites & contamination events
2. Expert elicitation of L. monocytogenes transfer dynamics
3. Creating a risk map of L. monocytogenes in retail delis
3. Estimating L. monocytogenes transfer coefficients
4. Estimating the efficacy of cleaning & sanitization
5. Summary & conclusions
22 / 25
Conclusions: Listeria transfers in retail deli environments
Transfers from environmental sites to food:
• Food contact surfaces greatest concern:
- high probability of transfer if contaminated
- contamination rel. unlikely but possible
- variable amounts of bacteria transferred
- contamination can become widespread
- occasionally high – efficiency transfers
• Non-food contact surfaces some concern:
- contamination is very common
- transfer to food rel. unlikely but possible
- transfer to hands / FCS’s major concern
Efficacy of cleaning / sanitization:
• Effective on clean surfaces, but:
- sanitizer efficacy differs
- external condition important
- lower efficacy possible
• Ineffective on soiled surfaces:
- impact differs by sanitizer
- cleaning (& drying) important
- potential residual bacteria
• Net efficacy of sanitizers:
- difficult to evaluate
- levels of Listeria unclear
23 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting
Acknowledgements: Too many contributors to name
- Everyone at FDA CFSAN, in particular:• Sherri Dennis• Régis Pouillot• Retail Food & Cooperative Program Staff
- Cornell University, in particular:• Martin Wiedmann• Haley Oliver (now at Perdue University)• Martin Wells• Yrjo Grohn• Food Safety Laboratory
- USDA FSIS & FSIS contractors, in particular:• Janell Kause• Meryl Silverman • Dan Gallagher (FSIS Contractor/VA Tech)
- Everyone else who contributed to the research, including:
• Food Marketing Institute - in particular Jill Hollingsworth & Larry Kohl for their support of the expert elicitation study
• Everyone at the enrolled ‘state’ departments that contributed to the expert elicitation study
• New York State Department of Agriculture & Markets – in particular Stephen Stich and Daniel Rice, for their support of the cross-sectional study of L. monocytogenes in NY retail establishments
• Everyone else who contributed!
This work was supported by the USDA Food Safety and Inspection Service (contact no. AG-3A94-C-09-0028).
K. Hoelzer was supported by Morris Animal Foundation Fellowship Training Grant Do8FE-403 for part of this work.
This work was supported, in part, by appointments to the Research Participation Program at the Center for Food Safety and Applied Nutrition administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US Department of Energy and the US Food and Drug Administration. 24 / 25
QUESTIONS?
NOTE: All literature citations available from presenter on request.
25 / 25May 22nd, 2013Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting