'Seek and destroy'
While some areas of industry have already addressed the pathogen, using a “seek-and-destroy” approach, along with “best practices” based on employee education, equipment and facility design and environmental monitoring, outbreaks are now being looked into more quickly by using Whole Genome Sequencing (WGS). This is a “fingerprinting” technology increasingly used as an industry and regulatory tool, GFSI participants at the meeting agreed.
“The irony is that there are probably fewer cases of Listeria in the meat and poultry industry. But because of this Whole Genome fingerprinting technology, there are more cases being discovered,” Mr. Doyle said. “And because of this innovative technology, instead of needing a large cluster of cases to tie sicknesses and manufacturing together, Listeria can be traced to a single company or manufacturer even if there are only two or three cases of illness.”
Doug Craven, corporate QC manager of sanitation for Hormel Foods, spoke at NAMI’s Advanced Listeria monocytogenes Intervention and Control Workshop. He said another factor making Listeria different from other pathogens and hard to control, is its ability to survive and grow in the cold.
“It can not only survive, but continue growing in refrigeration up to 32° F. Even in freezing temperatures, it won’t grow, but it will survive; it won’t be killed off. Add that to Listeria’s occurrence in the environment – in soil, on plant walls, contact and non-contact surfaces – it makes it difficult.”
In ready-to-eat (R.-T.-E.) meats, Listeria is an adulterant. In raw meat products that are cooked, the pathogen is killed. In raw products that are not cooked, including non-meat products, Lm can survive – in soil, produce, vegetables, and can be a problem, Mr. Craven said.
The key to control, Mr. Craven said, is the design of plant facilities to manage and prevent bacteria from entering the environment.
“NAMI and the industry have created 10 principles of sanitary design for all processors (non-competitive). They include making equipment cleanable to a microbiological level; materials must be compatible; surfaces must be accessible for cleaning and inspection; equipment must be self-draining to prevent harborage; no hollow areas in equipment; no niches; sanitary operational performance; hygienic design of maintenance enclosures; hygienic compatibility with other plant systems; and validated cleaning and sanitizing protocols.
“It is also very important not to cross-contaminate in plants. As employees enter an R.-T.-E. room, it’s very important for them to make sure they’re not bringing any Lm from the raw side,” Mr. Craven said. There also needs to be periodic 'deep cleaning.'
“Additives have been successful in keeping Listeria out, like sodium lactate and sodium acetate,” Mr. Doyle said, “because they act as antimicrobials, reducing the risk. When I was at the University of Wisconsin, Listeria was one of the first pathogens we worked on. Now these (deli) products are very safe.”
He voiced some concern about the “natural” and “clean label” movement in the industry, because keeping these kinds of additives out will lessen protection against Listeria and other pathogens. Environmental testing and final product testing are very important, he said.