Listeria, Salmonella, and E. Coli in Your Drains and Floor Cracks

By dciflooringUncategorized

When it comes to processing, preparing and manufacturing foods safely, plant managers understand the importance of diligent cleaning, disinfecting and sanitizing. Keeping an entire processing plant clean not only requires specific tools and procedures, but the proper understanding of how to eliminate food-borne pathogens and keep them under control.

By educating cleaning staff about these various pathogens and how to properly clean to control them, managers can have confidence that their food and customers will be safe.




While there are numerous pathogens that affect the food manufacturing industry, one of the most dangerous food-borne pathogens that exists today is Listeria – a bacterium that when present in foods, yields no difference in taste, smell or appearance. Listeria is the cause of the illness listeriosis. Nearly everyone infected with listeriosis is hospitalized, while one in five people or 20 percent will die from the disease.

To help lower the risk for an outbreak, it is important to know that Listeria is a bacterium that can also grow at refrigeration temperatures. This means that if Listeria migrates onto food, it may continue to grow even if the food is held at refrigeration temperatures during shipping, storage, and display, thus increasing the potential for illness. A listeriosis outbreak is devastating, not only to the individuals that became ill but to the food processor that made that food, if the illness can be traced to their facility. Depending on the size of a facility and the size of the outbreak, a food processing plant could be forced to throw out all of their products that may be contaminated with Listeria. The processor may also have to issue a recall of contaminated or potentially contaminated food. The processor will also have to take steps to ensure that the Listeria is eliminated from the processing environment. This may require the processing facility to be shut down for hours or days while the facility is cleaned and processing equipment is disassembled as needed and deep cleaned. Plant closings can cost thousands to millions of dollars in lost time, decreased productivity and reputation damage. In addition to those losses there may be fines and litigation costs that can be even larger.




Listeria multiplies by feeding off of organic soils. These soils can be found in many places in a food processing facility including trapped inside of coolers, chillers and drains. Cleaning floor drains is a traditionally unpleasant and complex task that tends to be neglected by cleaning staff. Drains that go uncleaned or are cleaned poorly can become more unpleasant over time, making it almost certain that they will be ignored. As a result of this cycle of neglect, Listeria is frequently found in floor drains. Listeria present in drains may migrate from drains onto surfaces where food is processed and handled, thus contaminating the food itself. Therefore, before Listeria can successfully be controlled and eliminated in a food processing environment, it needs to be eliminated from harborage points like floor drains.

There are many ways Listeria can transfer from floor drains to food. People walking or rolling carts or other equipment over surfaces contaminated with Listeria, as well as high pressure cleaning or vigorous scrubbing, may eliminate the organism. Equipment left or dropped on the drain, employees’ clothing, hands, and gloves and pests such as fruit flies can all provide ways for Listeria to move from a non-food contact surface like a floor drain to food or a food contact surface.



  • Fever
  • Stiff neck
  • Confusion
  • Weakness
  • Vomiting
  • Sometimes diarrhea


Who’s at risk?

  • Older adults
  • Pregnant women
  • People with weakened immune system
  • Organ transplant patients who are taking drugs to prevent the body from rejecting the organ





If cleaning staff use traditional drain-cleaning methods which typically include disassembling drains and brushing drain parts with brushes and pads, droplets of organic soil from the drain (possibly containing Listeria) can easily be released into the air. Once aerosolized, those droplets may settle onto food or food contact surfaces. A high pressure spray, as is often used for environmental cleaning in food processors, may also generate aerosols of soil from floor drains or other non-food contact surfaces. In addition, shoes, carts and other objects that move across the processing floor can also pick up droplets from the floor and send them to other areas of the facility or create aerosols as they splash through standing water. Equipment that is accidentally dropped or placed onto a drain can also pick up traces of Listeria and transfer them to food.

How is it controlled?

Effective control of L. monocytogenes requires prevention of contamination (to the extent possible) and prevention of growth through time/temperature or formulation control. Knowledge of potential harborage sites is important, as contamination is more likely to occur when the organism has become established in a niche. Food processing plant surveys have found Listeria in the following locations (listed approximately in the order of prevalence):
  • floors
  • drains
  • coolers
  • Cleaning aids such as brushes, sponges, etc.
  • product and/or equipment wash areas
  • food contact surfaces
  • condensate
  • walls and ceilings
  • compressed air


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Control of Listeria relies on detecting and managing harborage sites with thorough and frequent cleaning. This includes daily cleaning of floors and drains, and adequate attention to less frequently cleaned areas such as HVAC systems, walls, coolers and freezers. Also, damaged equipment, cracks, crevices and hollow areas must be part of sanitation and inspection schedules. It is essential to avoid creation of aerosols during cleaning, especially of floors and drains, to avoid spread of contaminants.

The organism is killed by normal food pasteurization and cooking processes, and is typically sensitive to most sanitizers at recommended rates. Contamination may occur after the cooking process in the processing environment, at retail locations and in the home. For example, post-pasteurization contamination of food products can occur when the organism is dispersed via an aerosol. Prevention of growth is essential to avoid the potential for illness, because L. monocytogenes can grow at refrigerated temperatures, defeating one of the traditional food safety measures.

L. monocytogenes can survive on cold surfaces and can also multiply slowly at 34° F. It has also been shown to grow to a water activity as low as 0.92 and over a pH range of 4.4-9.4.3 Because the organism can grow under refrigeration, effective labeling to ensure product rotation in retail settings is an important control measure for ready-to-eat products.

Since this organism continues to elicit concern among consumers, regulators, processors and retailers, studies need to be carefully designed to ensure validity.

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The Salmonella species of bacteria causes two types of illnesses: typhoidal illness and gastrointestinal illness. Typhoidal illnesses only affect humans and occur when people eat contaminated foods. Non-typhoidal salmonella poses a risk of gastrointestinal illness with as few as two bacteria, according to the U.S. Food and Drug Administration. A sink exposed to fresh produce, raw meat, dairy products or spices contaminated with the bacteria, as well as items that touched contaminated goods, pose a health risk. Fecal matter in sinks, which you may find in bathrooms, may also contain Salmonella.



  • Nausea
  • Vomiting
  • Abdominal cramps
  • Diarrhea
  • Fever
  • Chills
  • Headache
  • Blood in the stool


Who’s at risk?

  • Young children
  • Older adults
  • People with weakened immune systems




Escherichia coli (E. Coli)

Many Escherichia coli, or E. coli, strains are a beneficial gut bacteria, according to the U.S. Food and Drug Administration. However, there are six groups of the bacteria called “pathogenic” E. coli that transmit food-borne illnesses via contaminated food or water. A sink may contain the bacteria if it comes in contact with contaminated water and foods, or if a person carrying the bacteria touches the sink. The U.S. Food and Drug Administration says that an asymptomatic carrier of enterotoxigenic E. coli may unknowingly spread bacteria if he touches a sink or other items.




  • Abdominal pain
  • Diarrhea
  • Nausea
  • Vomiting (rare)
  • Fever
  • Fatigue


Risk Factors:
  • Young children and older adults are at higher risk of experiencing illness caused by E. coli and more-serious complications from the infection.
  • Weakened immune systems. People who have weakened immune systems – from AIDS or drugs to treat cancer or prevent the rejection of organ transplants – are more likely to become ill from ingesting E. coli.
  • Eating certain types of food. Riskier foods include under-cooked hamburger; unpasteurized milk, apple juice or cider; and soft cheeses made from raw milk.
  • Time of year. Though it’s not clear why, the majority of E. coli infections in the U.S. occur from June through September.
  • Decreased stomach acid levels. Stomach acid offers some protection against E. coli. If you take medications to reduce your levels of stomach acid, such as esomeprazole (Nexium), pantoprazole (Protonix), lansoprazole (Prevacid) and omeprazole (Prilosec), you may increase your risk of an E. coli infection.




When the opportunity for facility improvements and upgrades comes along, eliminating seams and harborage points along walls and floors, will go a long way in controlling and reducing niches and harborage sites that Listeria can get into and multiply. Many facilities are upgrading and moving to epoxy-coated, seamless walls, floors and coving to achieve an environment that helps ensure more cleanable surfaces. Equipment assessment, along with a “sanitary design program,” is an important part of environmental control against Listeria, Salmonella, and E. Coli. For existing equipment that may not meet sanitary design requirements, it would be best to implement a sanitary equipment upgrade program. Sanitary welds are an important part of equipment design and a successful environmental program. Equipment footings have presented themselves as harborage locations for water and food particles to collect or get caught up underneath.

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