Using risk assessment to design

effective intervention - Case study:

Listeria and deli meat

Martin Wiedmann

Department of Food Science

Cornell University, Ithaca, NY

E-mail: mw16@cornell.edu

Phone: 607-254-2838

Acknowledgements

• Funding sources: • USDA Food Safety and Inspection Service Contract # AG-3A-

C-09-0028 • USDA-NIFA Specials Research Grants

• Staff and students • S. Roof, C. Simmons, E. Wright, S. Warchocki, K. Hoelzer, B.

Sauders, M. Stasiewicz • Collaborators:

• New York state Department of Health; USDA-FSIS • Purdue University (Haley Oliver and Susan R. Hammons);

North Carolina Ag &Tech (Salam A. Ibrahim) • Retailers

Outline

• Listeria monocytogenes and deli meats – the issue

• The risk assessments addressing the issue – Interagency Risk Assessment – Listeria

monocytogenes in Retail Delicatessens Technical Report (slides provided by Janell Kause, USDA FSIS)

• The path forward: interventions • Conclusions and Lessons learned

Listeria monocytogenes

• Gram-positive animal and human food-borne pathogen • Facultative intracellular pathogen • Causes abortion, meningitis, and septicemia • Can grow at low temperatures • High infectious dose

• Causes an estimated 1,600 illness and 255 deaths/year in US • Equivalent to about 5 cases/million population • L. monocytogenes ranks #3 in number of deaths

due to foodborne disease per year in the US

FDA-FSIS Risk Assessment for L. monocytogenes in Ready-to-Eat Foods (2003)

Sample Source

*

VISIT 2

VISIT 3

VISIT 1

*

* *

*

* *

* *

* * *

*

*

* *

Sample Ribotype Sample Source RiboPrint® Pattern

1039C (E) Floor drain, raw materials area

1039C (E) Floor drain, hallway to finished area

1039C (IP) Troll Red King Salmon, in brine, head area

1039C (IP) Troll Red King Salmon, in brine, belly area

1039C (IP) Brine, Troll Red King Salmon

1039C (IP) Faroe Island Salmon, in brine, head area

1039C (F) Smoked Sable

1039C (F) Cold-Smoked Norwegian Salmon

1044A (E) Floor drain, brining cold room 1

1044A (R) Raw Troll Red King Salmon, head area

1044A (IP) Brine, Faroe Island Salmon

1045 (R) Raw Troll Red King Salmon, belly area

1045 (IP) Faroe Island Salmon, in brine, head area

1053 (IP) Norwegian Salmon, in brine

1062 (E) Floor drain #1, raw materials preparation

1039C (E) Floor drain #1, raw materials preparation

1039C (E) Floor drain, brining cold room 1

1039C (E) Floor drain #2, raw materials preparation

1039C (E) Floor drain #2, raw materials receiving

1039C (E) Floor drain, finished product area

1039C (E) Floor drain, hallway to finished area

1039C (IP) Brine, Troll Red King Salmon

1039C (F) Smoked Sable

1044A (IP) Sable, in brine

1044A (IP) Brine, Faroe Island Salmon

1062 (IP) Brine, Norwegian Salmon

7

L. monocytogenes persisted in rubber floor mats despite sanitation

Listeria can be protected from sanitizer in “micro-cracks”, but can

be squeezed out by pressure if people stand on mats

2000 US outbreak - Environmental persistence of L. monocytogenes?

• 1988: one human listeriosis case linked to hot dogs produced by plant X

• 2000: 29 human listeriosis cases linked to sliced turkey meats from plant X

From 2013 Interagency Risk Assessment: L. monocytogenes in Retail Delicatessens

Retrospective study provided evidence for L. monocytogenes

persistence in 16/50 retail establishments

Cross-sectional study provided data on L. monocytogenes prevalence

in different sites at retail (prospective study of 121 stores)

L. monocytogenes at Retail – Data from 241 Retail Deli Establishments in

New York State (2005 – 2007)

Phase Positive food

samples

Positive

environmental

samples

Stores with at

least one

positive sample

1. Large chain stores

(n=121)

2.7%

(5/183 samples)

13.0%

(151/1,161 samples)

60.3%

(73/121 stores)

2. Small stores

(n=60)

0.6 %

(1/157 samples)

12.9 %

(85/661 samples)

55.0%

(33/60 stores)

3. Stores with a history

of poor inspection

scores (n=60)

0.8%

(1/122 samples)

13.2%

(95/718 samples)

65.0 %

(39/60 stores) 12

Contamination originating at retail was estimated to account for 63 to 84%

of listeriosis cases due to selected RTE deli meats

Of those illnesses and deaths from L. monocytogenes from deli meat

consumption, approximately 83% are attributed to deli meat sliced and

packaged at retail facilities. 13

L. monocytogenes in retail

• 30 retail deli operations sampled monthly over 6 months

• Among 4, 512 samples 9.4% (424) were positive for L. monocytogenes

– 72/1604 (4.5%) of “Food Contact Surface” samples

– 18/540 (3.3%) of “Transfer Point” samples

– 334/2368 (14.1%) of “Non-Food Contact Surface” samples

L. monocytogenes Positive Samples by Site

Food Contact Non-Food Contact

Site + Total % Site + Total %

Slicer Blade 5 180 2.8 3-Basin Sink Ext 6 180 3.3

Deli Case 4 179 2.2 Floor-Wall Junct (3) 24 180 13.3

Case by Meat 2 33 6.1 1-Basin Sink Exterior 7 164 4.3

Deli Case Tray 4 180 2.2 Floor Wall Junct (1) 31 111 27.9

3-Basin Sink Intr* 14 179 7.8 Deli Drain 36 180 20.0

1-Basin Sink Intr* 30 164 18.3 Floor Adj to Drain 46 180 25.6

Cold Room Rack 4 180 2.2 Deli Floor 23 179 12.8

Cutting Board 3 152 2.0 Cold Room Floor 36 179 20.1

Rewrap table 1 179 0.6 Cold Room Wall 4 180 2.2

Counter 5 178 2.8 Cold Room Drain 40 119 33.6

Transfer Point Standing Water 16 90 17.8

Site + Total % Squeegee 36 132 27.3

Slicer Knob 3 180 1.7 Cart Wheel 14 180 7.8

Case Handle 8 180 4.4 Hose 6 134 4.5

Scale Top 7 180 3.9 Trash Can 9 180 5.0

*1- and 3 basin sink interiors are not considered food contact surfaces by FDA and USDA-FSIS

Presence of L. monocytogenes in Different Environments

• Natural environments: 1.4% (n=898)

• Urban environments: 7.4% (n=907)

• Ruminant farms – Bovine farms with listeriosis cases: 24.3% (n=616)

– Bovine farms without listeriosis cases: 20.1% (n=643)

– Small ruminant farms with listeriosis: 32.9% (n=322)

– Small ruminant farms without listeriosis: 5.9% (n=475)

Sauders et al., 2013, AEM; Nightingale et al. 2004, AEM

Store Month 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

FOOD CONTACT

07 0/9 0/8 1/9 0/9 0/9 0/7 2/9 0/9 0/8 1/8 0/9 0/6 0/9 0/9 0/9

08 0/9 5/9 0/9 0/8 0/9 0/7 0/9 0/9 0/8 3/8 0/9 0/10 0/9 0/9 0/9

09 0/9 0/9 0/9 0/9 0/9 0/9 0/10 0/9 0/8 1/9 0/9 0/9 1/9 0/9 0/9

10 0/9 0/9 0/9 0/9 0/9 0/7 0/9 1/9 0/8 1/8 0/9 0/9 0/9 0/9 0/9

11 0/9 0/10 0/9 0/10 0/9 0/10 1/9 1/9 0/8 1/9 0/9 1/9 2/9 0/9 0/9

12 0/9 1/9 0/9 1/8 0/9 0/7 0/9 0/9 0/8 1/8 1/9 0/9 0/9 0/9 0/9

TRANSFER POINT

07 0/3 1/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3

08 0/3 2/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 1/3 0/3 0/3 0/3 0/3 0/3

09 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3

10 0/3 1/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3

11 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 2/3 0/3 0/3 0/3

12 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3

NON-FOOD CONTACT

07 0/11 4/14 0/14 0/14 0/14 0/12 10/14 5/14 0/10 7/14 0/15 0/11 0/14 0/12 0/12

08 0/11 6/14 0/16 0/14 0/14 0/12 8/14 4/14 0/10 8/13 0/14 0/10 0/14 0/11 0/12

09 0/11 6/14 0/14 0/14 0/14 0/14 1/15 1/14 0/10 7/14 0/14 0/11 0/14 0/12 0/13

10 0/13 5/15 0/14 2/14 0/14 0/12 7/14 0/14 0/11 3/14 0/14 0/11 2/14 0/10 0/12

11 1/11 5/14 0/14 1/14 0/14 0/14 8/14 1/14 1/11 2/14 0/14 2/11 1/14 1/11 0/12

12 0/11 8/15 0/14 1/14 0/14 0/12 8/14 0/14 0/11 3/14 1/14 0/11 2/14 0/11 0/12

L. monocytogenes Positive Samples: Stores 1–15 by Month

14/30 retail delis showed evidence for L. monocytogenes persistence

April May June July August September October November December

Food Contact Sites

Sl icer - - - - - - - - -

Deli case NT NT NT - - - - - -

Deli case near raw meat NT NT NT - - - - - -

Deli case trays NT NT NT - - - - - -

3-basin sink interior NT NT NT CU-57,267 - - - - -

1-basin sink interior NT NT NT CU-258,69 - - - CU-294,321 -

Cold room rack - - - - - - - - -

Cutting board NT NT NT NT - - NT NT -

Rewrap table NT NT NT - - - - - -

Counter NT NT NT - - - - - -

Non-food contact sites

3-basin sink exterior NT NT NT - - - - - -

Floor/wall junction (3-basin) CU-258,69 CU-258,69 CU-258,69 CU-258,69 CU-258,69 CU-8,96 - - CU-258,69

1-basin sink exterior NT NT NT CU-258,69 - - CU-258,69 - CU-258,69

Floor/wall junction (1-basin) NT NT NT CU-258,69 - - CU-258,69 CU-258,69 CU-258,69

Deli drain NT NT NT CU-258,69 CU-258,333 - - CU-258,69 CU-258,69

Floor adjacent to drain - CU-258,69 CU-258,69 CU-258,69 CU-258,69 - CU-258,69 CU-258,69 CU-258,69

Deli floor NT NT NT CU-258,69 - - - CU-258,69 -

Cold room floor NT NT NT CU-258,69 CU-295,329 - CU-258,69 CU-258,69 CU-258,69

Cold room wall CU-258,69 - - - - - - - -

Cold room drain NT NT NT CU-258,69 CU-258,69 - CU-258,69 CU-258,69 CU-258,69

Standing water NT NT NT NT - - NT NT -

Squeegee NT NT NT CU-258,69 CU-258,69 - CU-258,69 CU-258,69 CU-258,69

Cart Wheel - - CU-258,69 CU-258,69 - - - - -

Hose NT NT NT - CU-258,69 - - - -

Trash can - - CU-258,69 - CU-258,69 - - - -

Transfer Points

Slicer knob - - - - - - - - -

Case handle - - - - - - - - -

Scale NT NT NT - - - - - -

19

20

Effects of sanitation related scenarios on Predicted Risk of Invasive Listeriosis for the

Susceptible Population

Scenario Multiple

Niche

100W

No

Niche

Incoming

Growth

Chub

Incoming

Non-growth

Chub

Temp.

Control

Niche &

Temp.

Control

Wash & Sanitize: Increase the

effectiveness of cleaning from simply

washing to washing and sanitizing.

-1.6 1.7 -0.6 2.0 -1.3 -7.6*

Clean 8 Sporadic: Double the number

of sites cleaned from 4 to 8.

-4.2 -4.1* -0.7 -1.9 -0.5 1.3

No Sanitation: No wiping, washing, or

sanitizing.

41.3* 7.9* 2.9* 23.5* 11.9* 50.2*

No Sporadic Cleaning: Clean as

required by the 2009 FDA Food Code,

but no additional sporadic cleanings.

3.0 -3.0 -0.4 1.7 1.7 3.5

NFCS As FCS: Workers clean deli

NFCSs at same rate as FCS.

-3.0 0.7 -0.6 0.3 -5.4* 0.9

Scenario Multiple

Niche

100W

No Niche Incoming

Growth Chub

Incoming Non-

growth Chub

Temp.

Control

Niche & Temp.

Control

No Glove: Workers do not use

gloves when serving customers.

5.1* 2.5 1.2 8.5* 6.0* 7.0*

No Contact Glove Case: Workers

do not use their hands to open

the deli case (e.g. if a floor

switch is used).

-1.4 -3.4 -1.3 1.3 1.3 -0.3

Pre-slice: Workers pre-slice RTE

products in the morning, after

cleaning

6.0* 24.9* 49.5* -34.4* 19.2* 1.0

Separate Slicer: Workers use a

separate slicer for RTE products

that support growth of L.

monocytogenes.

-6.3* -0.6 -1.7* 22.7* -0.8 4.6

Effects of selected worker behavior related scenarios on Predicted Risk of Invasive Listeriosis

for the Susceptible Population

Scenario Multiple

Niche 100W

No Niche Incoming

Growth

Chub

Incoming Non-

growth Chub

Temp.

Control

Niche & Temp.

Control

All GI: Reformulate all RTE

products sold at the retail deli

that would otherwise support

L. monocytogenes growth to

include growth inhibitors.

-96.0* -95.2* -97.5* -94.5* -94.4* -94.8*

No GI: Reformulate all RTE

products that support L.

monocytogenes growth that

are sold at the retail deli to

not include GI to restrict L.

monocytogenes growth.

184.1* 191.5* 35.1* 190.5* 187.7* 188.9

Effects of growth inhibitor related scenarios on Predicted Risk of Invasive Listeriosis for the

Susceptible Population

Effects of selected cross contamination related scenarios on Predicted Risk of Invasive Listeriosis

for the Susceptible Population

Scenario Multiple

Niche 100W

No Niche Incoming

Growth Chub

Incoming

Non-growth

Chub

Temp.

Control

Niche & Temp.

Control

Transfers to 0: Cross

contamination results only

from the deli slicer.

-4.3 2.5 1.0 3.7 0.2 -0.3

Transfers and Slicer to 0: No

cross contamination in the

retail deli.

-33.8* -18.6* -9.5* -60.8* -19.2* -30.4*

Reduce Level: Mean incoming

L. monocytogenes log10

concentration in all RTE

products lowered from -9.2 to

-9.5 log10 cfu/g.

-21.6* -24.2* -1.1 -9.8* -22.5* -15.6*

Effects of selected storage time and temperature related scenarios on Predicted Risk of Invasive

Listeriosis for the Susceptible Population

Scenario Multiple

Niche 100W

No Niche Incoming

Growth

Chub

Incoming

Non-growth

Chub

Temp.

Control

Niche & Temp.

Control

Temp = 5°C: Set the retail

deli case temperature to

5°C (41°F)

-4.8 -14.3* -8.1* -2.8 NA NA

No Growth (T=-5°C): At this

temperature, no L.

monocytogenes growth will

occur.

-16.5* -21.3* -18.2* -5.7* NA NA

Shorten Time in Retail

Delis: Reduce the length of

time RTE products are held

before they are sold or

disposed from 7 to 4 days.

-2.5 3.3 -1.2 2.0 -0.2 1.7

Interventions to control L. monocytogenes at retail

• Control growth in deli meats through reformulation – Based on various models, this is by far the most effective

intervention

• Control cross contamination – Multiple contributing factors (employee behavior, niches) – No simple solutions

• Control contamination on incoming products • Continued focus on sanitation • Focus on key routes of contamination and cross

contamination (e.g., slicers)

Summary and conclusions

• L. monocytogenes contamination is a challenge across the food chain, not just in processing facilities – Common presence of L. monocytogenes in many environments

presents a considerable challenge • Risk assessments and growth modelling data suggest the

reformulation of RTE deli meats represents the most effective intervention

• Do not trust risk assessments too much: – Many aspects of the complexity of food systems are difficult to

model – We model what we can wrap our head around and what we

have data for • Over-reliance on insights based on outbreaks can be dangerous