Be Ready to Beat Listeria

The foodborne pathogen Listeria monocytogenes has remained a major concern in all food markets but is especially problematic for ready-to-eat (RTE) products. Its high level of morbidity—nearly 30% in those at greatest risk (pregnant woman, the elderly, young children, and the immunocompromised)—makes it a high priority in RTE plants.

A major Listeria monocytogenes outbreak in fall 2002, triggered by an RTE luncheon meat processor in the Northeast, served as a catalyst for the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) to bolster its control measures.

This enhancement includes validation-verification programs to prevent contamination by Listeria monocytogenes and generic Listeria. The revised versions of these guidelines—10,240.4 Rev. 1 and 10,240.5, dated March 15, 2006—delineate three “alternative control” programs available to RTE FSIS plants, along with the enforcement measures FSIS field inspectors must implement.

Federal Oversight

The first key legislative directive that resulted in mandated federal regulations was the 2002 “Microbial Sampling of Ready-To-Eat (RTE) Products for the FSIS Verification Testing Program.” This document details FSIS’ rationale for implementation, as well as key terminology. The three parts of this document provide decision-making criteria for FSIS-regulated RTE plants.

The first part differentiates high-, medium-, and low-risk products, taking into account products that have undergone so-called post-lethality treatment. It classifies RTE products into four groups:

• not heat treated and shelf stable;
• heat treated and shelf stable;
• fully cooked and not shelf stable; and
• product with secondary inhibitors and not shelf stable.

These categories are further defined in 9 CFR Part 430. FSIS includes frozen products in the RTE foods category.

The second part is the nuts and bolts of the 2002 directive. This statement of policy focuses on enforcement levels in programs testing for Listeria monocytogenes in finished products, in food contacts, and on environmental surfaces.

Plants that have a science-based Listeria monocytogenes control program and share data with FSIS will be tested under a targeted verification program. Producers of high to medium-risk products that have no science-based control program and don’t provide data to FSIS will undergo an intensified verification program—FSIS will take more samples from more products. Further, if a Listeria monocytogenes positive is found either in product, in food contacts, or on environmental surfaces at any enforcement level, the FSIS can put a plant under the most rigorous scrutiny.

The last part of the directive deals with regulatory actions and sampling when a product or surface sample is found to have any of the “big three” (Listeria monocytogenes, Salmonella, and E. coli 0157:H7). For example, if a food contact is found to have Listeria monocytogenes, the FSIS will most likely request a recall for a product that has been shipped. This, of course, puts pressure on plant sanitation programs, emphasizing the need for both internal and external support, for the following reasons:

• If an environmental surface is found to have Listeria monocytogenes, the RTE plant must adhere to the corrective actions described in the plant’s hazard analysis and critical control point (HACCP) program and sanitation standard operating procedures documents.
• The section on food contact surface testing for indicator organisms focuses on corrective actions if indicator microbe levels are present.
• The FSIS expects the plant to “take additional steps to thoroughly clean and sanitize potentially contaminated food surfaces and increase the number of food contact surface samples that it takes.”

This directive has required RTE food plant quality assurance and sanitation programs and their technical resources to double their focus on these programs, utilizing a multi-pronged control strategy with Listeria monocytogenes but also targeting Salmonella spp. and E. coli 0157:H7. This is most acute for post-lethal treatment production processes, where recontamination with Listeria monocytogenes after a heat kill step threatens RTE products.

RTE Alternatives

This RTE directive was codified as an Interim Final Rule on June 6, 2003 (“Control of Listeria monocytogenes in RTE Meat and Poultry Products;” Final Rule as 9 CFR Part 430) and revised on January 1, 2006.