USDA Food Safety and Inspection Service 

= US Offi\RTf,ENHlf AGA!CU.TLRE 

Agenda 

Part I. Overview and Background of T 

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Part I. Overview and Background of Lm

Part II. Lm Sampling

Part III. Lm Outbreaks

Part IV. IVT and RLm Testing Results

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What is Lm? 

Control of Lm 

How Does Lm Get Into Establishments 

Pathogenic bacteria that causes listeriosis

RTE Post-processing contaminant

Forms biofilms and harborage sites

Spread by water, dust, etc.

Moisture facilitates growth,

harborage, and cross-contamination

Products and food contact surfaces

(FCS) are often contaminated from

environmental (non-food contact

surfaces (NFCS)

Survives a wide variety of extreme

conditions (heat, salt, nitrite,

acidity).

Lm

8/18/2022

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• Proper sanitation

• In-plant pasteurization

• Establishments should have support for

the safety of incoming produce

• Workers should follow GMPs – change

gloves, should not wipe their nose and

touch product, etc.

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 Once established, Listeria is nearly

impossible to eradicate completely.

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HUMANS

EQUIPMENT

PALLETS AND SUPPLIES

INGREDIENTS AND WATER

VEHICLES
 

 

 

 

 

 

 

 

 

 

 

 

 

How does Salmonella get into RTE products? 

P-art II. Lm Sampling 

Lm Sampling 

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• Incidence of Salmonella in RTE products is much lower than Lm

• RTE products can be contaminated with Salmonella:

• Under processing

• Ingredients added after lethality (spices, sauces) – Appendix A

• Cross contamination – Product contact surfaces contaminated with Salmonella

• Improper handling by employees

• Insect and animal vectors

• Areas that may be overlooked during sanitation

• Flow of people, supplies, ingredients, etc.

• Exposed product contamination

• Workers’ hands and aprons

• High contact areas (e.g., keypads, doorjambs, door handles)

• Moisture and condensation

• Areas that are difficult to clean and sanitize effectively

HTF14

HTF15

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Slide 9

HTF14 (BW 06/07)There are two parts, cleaning which is the removal of

debris and sanitization which is killing of micro organisms. Many

establsihments fail to support both parts in LTD situations. So my

recomendation is to always say these twwo things together.,

perhaps even explain it.

Hazard, Tennetta - FSIS, 6/14/2022

HTF15 I've never seen cracks and crevices sanitized in establishments.

Crevices of equipment are washed, rinsed and sanitized, but cracks

(in floors, walls etc.) are usually repaired.

Hazard, Tennetta - FSIS, 6/14/2022
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lm Sampling: Food Contact Surface (FCS) 

Lm Sampling: Food Contact Surface (FCS) 

Environmental, Non-Food Contact Surface (NFCS) Sampling 

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• FCS: An area in the post-lethality processing environment that comes in

direct contact with post-lethality exposed RTE product.

FCSs FCSs: Cooking and

Cooling FCSs: Employees FCSs: Packaging

• Tables

• Conveyor Belts

• Chutes

• Cutting Boards

• Blades and hopper

surfaces of slicers

• Hooks and hopper

surfaces of shredders

• Blade and table of

• Racks

• Pans

• Tubs

• Brine for chilling

• Utensils: knives,

tongs, thermometers

• Aprons (touches

product)

• Gloves/hands

(touches product)

• Low priority

• Storage and handling 

of packaging material

• Film wrap

• Bags

• Soaker pads

saws

• Some pieces of equipment have both FCSs and NFCSs

• Notate exactly where each sample was collected

• Take good sampling notes

Activity

Question: Which part is an FCS area?

Answer: Employee’s gloved hands

Question: Which part is the NFCS?

Answer: The slicer handle

• NFCS: A surface that has no direct contact with exposed product.

• EIAOs may collect samples from any area FSIS RTE product is processed,

held, or stored.

• Collected in other areas associated with post-lethality exposed, RTE

processing.

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Environmental, Non-Food Contact Surface (NFCS) Sampling 

NFCS Sampling Sites 

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NFCSs

Collect near FCSs

• Wet spots on floors and walls, low places on floors where

water collects, and door jambs

• Entrances where workers or equipment can track Lm

• Wheels of equipment

• Anything associated with moisture and condensation:

overhead pipes, drains, squeegees, drip pans

• Handles, switches, and control buttons

• Bottom, front and side edges of stools or chairs used by

employees

• Equipment that overhangs product

• Undersides of solid conveyer belts

• Compressed air or vacuum lines

• Oven smokehouse exit areas

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Past Outbreak Related Positive RTE FCSs 

Past Outbreak Related Positive NFCSs 

Construction in the Plant 

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SAMPLE RATIONALE

Tray for deboned ribs Extensive hand contact

Surface of portion scale Extensive hand contact

Belt entering beef slicer Index Sample

(post op)

Top belt entering slicer Index Sample

(post op)

Slicer blades (post op) Index Sample

Weighing bowl for sliced Index Sample

beef

SAMPLE RATIONALE

Wet spots at floor/wall junction Possible harborage

Underside of rib deboning table Sanitation overlooked

Condensation Possible harborage

Freezer door jamb Common contact point

Electrical Switches Common contact point

Drains Possible harborage

Table that trays pass over Sanitation overlooked

Door jamb gap between door and wall Possible harborage

• Bil Mar Foods Facility, Michigan: 11 states, 50 illnesses, 6 deaths, 2 spontaneous abortions

• Demolition of a refrigeration unit increased environmental contamination

• Condensation falling from overhead pipes and the ceiling onto exposed product

• Recalled 35 million pounds of hot dogs and deli products

• Plantation Foods, Texas: 10 states, 29 illnesses, 4 deaths, 3 miscarriages or stillbirths

• Construction of the walls and floors

• Walls harbored Lm (led to cross-contamination)

• Recalled 16.7 million pounds of products

• Deli turkey meat probable source of infection

Controlling Listeria monocytogenes in Post-lethality Exposed Ready-to-Eat Meat and

Poultry Products (Construction pp. 76 – 77)

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IVT Results (2005-2014) 

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IVT Results (2005-2014) 

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Product Sampling Results

• Products with the most

positive results:

• FC Multicomponent

Products

• Salads, Spreads, Pâtés

• Other Products

FC = fully cooked

Other = individually have not come up positive

often or are not sampled often

FC Multicomponent

37%

FC Salads, Spreads, Pates

16%

Other Products

12%

FC Diced, Shredded

Products

11%

FC Sausage Products

8%

FC Hotdog Products

6%

FC Patties, Nuggets

5%

FC Deli-Sliced Products

3%

Fermented Products

2%

FCS Sampling Results

• Products with the most

positive results:

• Other FCSs

• Conveyors/Conveyor

Belts

• Blades, Knives

• Why do knives test

positive so often?

Other FCSs

23%

Conveyors/Conveyor

Belts

16%

Trays, Pans Blades, Knives

Cutting Boards 2%

11% 12%

Slicers

8%

Tables

7%

Gloves

7%

Racks

4%

4%

Mixers

4%

Chutes Scales

2%

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IVT Results (2005-2014) 

RLm Results (2006-2014) 

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RLm Results (2006-2014) 

* 

* 

UD 

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• Products with the most

positive results:

• Drains

• Other NFCSs

• Wheels

Drains

27%

Other NFCSs

20%

Wheels

14%

Floors

12%

Doors

7%

Tables

4%

Walls

3%

Pallets/Pallet Jacks

3%

Floor Mats

3%

Boots/Shoes

2% Slicers

2%

Squeegees

2%

Conveyors

1%

Environmental Sampling Results

• Products with the most

positive results:

• FC Multicomponent

Products

• Other FC Products

• Fermented Products

FC Multicomponent

Products

22%

Other FC Products

13%

Fermented Products

14% FC Sausage Products

11%

FC Hotdog Products

8%

FC Diced, Shredded

Products

8%

FC Sausage

8%

FC Deli-Sliced Products

8%

FC Salads, Spreads, Pates

5% FC Patties, Nuggets

3%

Product Sampling Results

• Products with the most

positive results:

• Other FCSs

• Blades, Knives

• Tables

Other FCSs

19%

Tables

17%

Blades, Knives

13% Slicers

12%

Conveyors/Conveyor

Belts

10%

Gloves

7%

Scales

7%

Trays, Pans

6%

Chutes

4%

Scoops

2% Mixers

2%

Cutting Boards

1% FCS Sampling Results

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RLm Results (2006-July 2009) 

* * * 

Take-Aways 

~ 

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• Products with the most

positive results:

• Drains

• Wheels

• Other NFCSs

Drains

30%

Other NFCSs

21%

Wheels

15%

Floors

13%

Squeegees

6%

Floor Mats

6%

Boots, Shoes

3%

Walls

2%

Slicers

2%

Pallets/Pallet Jacks

2% Environmental Sampling Results

Lm can survive a wide range of environmental conditions and thrivesin moisture

Lm is known to form biofilms

Establishmentsshould control sanitation

Anything brought into the post-lethality RTE environment should be thoroughly cleaned

and sanitized

Construction in the RTE area is high risk for Listeria contamination

Take good sampling notesthat describe what was sampled and where the sample was

collected

QUESTIONS

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