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Listeria Risks for the Food Service Industry

Published by Harmony Lab & Safety Supplies on Jan 09, 2024

Listeria is common in the food services industry.

Regular surface testing is a worthwhile investment to ensure your procedures are working.

Listeria is a type of bacteria that causes listeriosis, a serious illness with a fatality rate of 20%. Most cases involve hospitalization. Children, the elderly, and adults with weakened immune systems are most susceptible. Healthy adults may avoid listeriosis but are still susceptible to gastroenteritis.

Vomiting, abdominal pain, and diarrhea are the most common symptoms. If the bacteria spreads beyond the gut, a fever may arise. Some doctors may mistakenly diagnose patients with “stomach flu,” although listeria is unrelated to influenza. A bacterial culture verifies listeriosis.

It is impossible to prevent this bacteria from entering your setting. It survives extreme cold, acidic, and oxygen-deprived environments. Refrigeration and freezing do not prevent listeria growth. 

In fact, listeria continues to grow in the cold. Because of its durability, the only way to prevent listeria contamination is through proper training and procedures. Cleaning and sanitizing equipment is not enough. 

Listeria can survive in HVAC systems, floors, crevices, or hard-to-reach places. Without sufficient procedures, your company may be liable for any lapses that cause a listeria outbreak. Fines, fees, and litigation will increase costs on top of product recalls and reputation damage.


Cleaning and Sanitizing to Prevent Listeria

Safety is the first priority for the food industry. Cleaning and Sanitizing (C&S) are the key components to fulfill your responsibility. Cleaning involves removing all surface-level contaminants such as food, oil, and dirt. Bacteria cling to these contaminants and block chemicals from reaching the surface. All work surfaces require cleaning, including walls, drains, and floors.

All machinery should be broken down into its base components in order to properly sanitize each element. Bacteria festers in hard-to-reach places. Once a significant amount of bacteria congregate in one area, it forms a biofilm that can prevent proper sanitization.

Biofilms

It is common for drains to contain biofilms. Because they are overlooked and cleaned less often, it can be ground zero for a listeria outbreak in your facility. If a drain contains a biofilm, then cleaning and sanitizing will not be sufficient. The bacteria will spread onto the floor through the drain onto employee boots and clothes. If a pressurized washer is used to clean drains, then the blast will spread listeria through the air onto equipment. If drains flood, production should be ceased immediately. Slot drain systems prevent bacteria from festering. Otherwise frequent cleaning is the best way to prevent biofilms and listeria.

Detergents

Solvents, detergents, acids, and abrasive cleaners are the most common cleaners used.

Detergents are useful for lifting most soil from the surface. Solvent cleaners can be used for grease even when grease has burned onto the surface. Acid cleaners are used on mineral deposits such as hard water. Abrasive cleaners remove significant soil accumulations, generally in small areas. Because of its abrasive qualities, its use should be limited to surfaces not cleaned by a detergent.

Surfaces must be cleaned of all organic material. Bacteria feed off organic material and prevent proper sanitization.

Cleaners do not remove all microorganisms and bacteria. Sanitizers must be used in conjunction with cleaners.

Sanitizing

Sanitizing proceeds cleaning. It involves applying chemicals or heat to a cleaned surface. Although sanitization does not sterilize an environment, it is sufficient for most settings. Heat is useful because listeria cannot survive past 149 degrees Fahrenheit or 60 degrees Celsius. Properly cooked food will not contain listeria if heated past 149 degrees. Dishwashers reach this temperature and thus, too are effective means to sanitize.

Chemicals are used for food-contact surfaces. Chlorine, iodine, and medical cleaners such as quaternary ammonium compounds are all approved for food-contact surfaces.

Chlorine

Chlorine is the most common sanitizer. It is effective against bacteria, fungi, viruses, and spores. Salmonella, cryptosporidium, and giardia are all resistant to chlorine. In instances involving chlorine-resistant microorganisms, quaternary ammonium compounds work effectively. Chlorine is ineffective against biofilms and is toxic when inhaled and in contact with skin. A positive residual effect keeps the surface free of bacteria for a limited time.

Iodine

Iodine is an acid sanitizer. It is effective against bacteria, fungi, viruses, and tuberculosis. Iodine is slightly resistant to listeria, meaning longer exposure times are necessary. To remove a listeria-infested biofilm with iodine, soak the film. Because iodine is an acid, be careful when it comes into contact with other sanitizers. Chlorine mixed with an acid produces a deadly, toxic gas. If exposed, immediately remove everyone from the environment. Iodine is also extremely corrosive and causes chemical burns on the skin.

Proper protection is required when cleaning with acids like iodine.

Quaternary

Quaternary ammonium cleaner is effective against vegetative bacteria. Vegetative bacteria is bacteria that is not growing. QA is effective against biofilms and does not require soaking time like iodine. Like chlorine, QA provides residual activity, keeping the surface sanitized for a limited time. It works against hard water, although QA itself is not corrosive.

Sanitizers

Sanitizers react differently depending on the surface. Plastic, glass, metal, and wood may require different sanitizing chemicals. For food environments, this may not be as important. Understanding the microorganisms that thrive in your environment is critical to prepare proper sanitization procedures. For example, if you have a biofilm with listeria, then your iodine sanitizer may not be enough if the film is not soaked for an adequate time. In that case, QA could be used. Send environmental samples to labs in order to sanitize properly.

Sampling For Lab Tests

Listeria is unique in that contaminated foods appear and taste normal. Because of this, environmental monitoring should be a part of every facility’s procedures, along with a cleaning and sanitizing program. Swab sample collection will keep your facility safe. Samples will identify listeria and other pathogens.

Once you know what pathogens live in your environment, you will be able to use the right sanitizers to protect your customers.

Environmental sampling kits are designed to increase sample count through their large, foam-tipped swabs. A swab is secured to the screw-cap in leak-resistant tubes in all kits. To test, remove the swab and wipe the sample area while rotating the swab. Return the swab to the tube and secure the cap. 

Laboratory analysis should be completed within 4 hours. Samples can be refrigerated for up to 24 hours at 35-39 degrees Fahrenheit or 2-4 degrees Celsius.

To prevent sample sanitizer contamination, sampling swabs come pre-moistened with neutralizing solutions.

Neutralizing solutions can interact with microorganisms, potentially harming the pathogens you hope to test. 

To prevent this, your swab needs to be tailored to your environment. Contact our customer service if you need advice on which swab is best for you.