Biofilms bring safety challenges to food companies

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In the first installment of this series with Sterilex, Food Safety News explores what biofilms are and their unique resistance to attempts to kill the pathogens they protect.

Food processors and manufacturers know the environments in which they operate are friendly to organisms that can taint their products, potentially leading to foodborne illness outbreaks.

Food safety plans and specific good manufacturing processes outlined in those documents are designed to combat common pathogens — including strains of Listeria, Salmonella and E. coli — that could lead to recalls or outbreaks.

Whether or not food safety plans specifically mention “biofilms,” in many cases they are the root cause of contamination in food facilities. Approximately 60 percent of foodborne illness outbreaks are caused by biofilms, according to food safety research.

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What are biofilms?
Essentially, biofilms are communities of micro-organisms that stick to surfaces. They are naturally occurring and can be found clinging to everything from plant and animal tissue, drug devices such as implants, water system infrastructure, and of course, in manufacturing facilities.

“Biofilms are everywhere in nature. . . . (They) are the natural state of organisms and have been around since the beginning of time,” said Bob Forner, director of marketing for Sterilex Industries, which supplies products designed to detect and kill biofilms for food processing, animal health, and water treatment industries.

Biofilms can harbor clusters of specific pathogens or a combination of them. In production facilities, food contact surfaces are hotspots on which to focus biofilm sanitation efforts, because of the possibility cross-contamination will occur — repeatedly, if not properly treated.

“They are significantly more challenging to kill” than pathogens found in free-floating (known as planktonic) cells in liquids, Forner said.

Why are biofilms so hard to eradicate?
The pathogens themselves produce what is known as a matrix of extracellular polymeric substance (EPS) made up of proteins, lipids, polysaccharides, and nucleic acids. The EPS gives the pathogens a protective home that resists sanitation efforts.

“Free-floating bacteria basically form a group to help protect themselves.” Forner said. “While traditional sanitizers are effective against these free-floating bacteria, they don’t necessarily allow you to kill all of the pathogens within the biofilm.”

Fighting a biofilm with these traditional sanitizers is like peeling layers from an onion, you’re really just addressing the bacteria on the surface he said.

“Even if you succeed in killing all of the pathogens in the biofilm, you will likely still leave the EPS structure behind” Forner said. “Without removing the structure from the surface, it’s a lot easier for the microbes to repopulate the biofilm.”

Biofilm research and awareness on the rise
Tests that detect salmonella or other pathogens on food contact surfaces don’t necessarily indicate the presence of biofilms, but Forner said the food safety community is aware of the dangers they pose.

“I think recently there’s been more of a focus on them as a source of foodborne illness,” he said. “A lot of the endemic pathogens that are in food plants are housed in biofilms and that’s why they’re so hard to get rid of.”

He said organizations such as the International Association of Food Protection are targeting biofilm content at conferences and educational outreach to food companies.

“Industries are more aware of them than they have been in the past and as a result, they do put more emphasis on trying to remove those biofilms from surfaces,” Forner said.

Boce Zhang, who led a Center for Produce Safety-funded study on different food contact surfaces in processing plants and their ability to resist biofilm growth, said biofilm is a natural survival mechanism that enhances the advantage of bacteria.

“It is imperative to understand the role of biofilm on the likelihood of pathogen survival and transmission,” said Zhang, assistant professor of Biomedical and Nutritional Sciences at the University of Massachusetts. “Addressing biofilm challenges requires a holistic approach and novel control strategies.”

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