Risk Mapping and Listeria monocytogenes Transfer in Retail Delis Karin Hoelzer, PhD FDA / Cornell...

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

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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


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)


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)

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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


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


Introduction: A risk map is useful to focus interventionsP

reva

len

ce o

f co

nta

min

atio

n

Probability of transfer to food




Low riskLow control



1. Introduction









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


Expert elicitation: Responses differed, but not by employer


Study design:

• ‘Delphi’ method

• 45 experts enrolled:

- 20 from retail industry

- 25 from the states

• 2 questionnaires

• telephone conference

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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



Expert elicitation: Transfer from hand-touch surfaces likely



Risk mapping: Risk maps analyze risks & can guide actionsL

ikel

iho

od

of

occ

urr

ence

Expected impact




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)



1. Introduction









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

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1. Introduction









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



1. Introduction








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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


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.


Risk Mapping and Listeria monocytogenes Transfer in Retail Delis Karin Hoelzer, PhD FDA / Cornell...

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