Control of Listeria in Processing Plants - bioMérieux

Control of Listeria in Processing PlantsbioMérieux’s Food Safety Signature WorkshopWendy McMahon, Silliker, Inc.Plant Hollywood Resort & CasinoSeptember 29, 2012

Significance of Listeria monocytogenesPsychrotroph• Multiplies at refrigeration temperaturesListeriosis• High fatality rate ranging from 20% - 30%• High risk populations• Pregnant women• Immuno-compromised• Elderly• Manifestations• Septicemia, Meningitis, Encephalitis, Intrauterine or cervical infections inpregnant women (results in spontaneous abortion or stillbirth)• Gastrointestinal or influenza-like symptoms such as nausea, vomiting,diarrhea and fever may precede more serious forms of listeriosis or may bethe only expressed symptom.http://www.fda.gov/downloads/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/UCM297627.pdf

Significance of Listeria monocytogenesReady-to-Eat refrigerated foods considered high risk• Ability to grow at refrigerated temperatures• Coupled with high fatality rateConsumer protection depends on preventingcontamination in those foods in which growth can occur• Intervention strategies• Control measures

Top Reasons for FDA Recalls - 2011Quality7%Mislabeled20%Microbial30%Sulfites3%Heavy metals2%Ex mat3%Undeclaredallergens35%

Reasons for FSIS Recalls - 2011Ex Mat5%E. coli O157:H712%Residue1%Misbranding8%Undeclaredallergen38%Other13%Listeriamonocytogenes11%Salmonella10%Processingdefect2%

Listeria monocytogenes (Lm) ProductRecalls in the United States, 2006-2007Food Product Total #Prepared foods 32Fish, seafood products 27Meat & poultry products 23Dairy products 7Fruits, vegetables 2Grand Total 91*Most of these recalls resulted from post-process contamination6

Food Recalls – Listeria monocytogenes2011FDA and FSIS Recalls Due to Listeria - 2011Meat/Poultry20%Dairy25%Fruit or Vegetable22%Prepared foods11%Spices2%Seafood20%7

The Value of a Listeria sp. EnvironmentalMonitoring ProgramMany recalls of finished product are due to the presence of Listeriamonocytogenes resulting from post-process contamination.Environmental monitoring for Listeria species can identify growthniches and transfer points.Corrective actions to eliminate or control identified sites candramatically reduce the risk of L. monocytogenes contamination.Use of testing to identify, monitor and control is an important toolfor preventing contamination.8

Critical Aspects of Preventing Post ProcessContaminationPrevent the introduction of (Lm) into the post process environment.Prevent growth of (Lm) in the post process environment.Prevent distribution of (Lm) from contaminated areas to productcontact areas.9

The Ideal Food Plant LayoutRawMaterialRawProcessingAreaKillStepPackagingAreaShippingNote: Same issues apply to food preparation inhomes and foods service operations10

Microbial Mapping of the Plant Environment“Mapping” is a microbial survey of a plant environment.Identify equipment and plant environment locations for sampling.Use “zone concept”.Sample all sites several times before starting environmentalmonitoring program to eliminate original contamination and getenvironment under control.11

Sanitary ZonesZone 1Zone 2Zone 3Zone 4Food Contact Surfaces (FCS)- slicers, conveyors, peelers, striptables, utensils, racks, work tablesNon FCS-Exterior of equipment; chill units; framework;equipment housing, floorsNon FCS-Phones; mules; forklifts; walls; drainsRemote areas–Non FCS-Locker rooms, cafeteria, halls

Sanitary ZonesZone 1Zone 2Zone 3Zone 4

Requirements for Microbial GrowthMicrobialGrowth NicheFoodContaminationWaterTime

Growth NichesLocations harboring the organism after the routine sanitationprocess for that area has been completed.Example– Hollow roller on conveyortransporting food productHollow rollers not disassembledcleaned and sanitized orheat treated in a manner toeliminate any contaminatingorganisms can becomegrowth niches.

Growth NichesHollow roller with solid stainless steelshaft in center (almost press fit).When center shaft removed organicmatter is evident.

Transfer Points vs NichesMany positive sites found during monitoring are not growthniches. They are transfer points (i.e., a product handler’sgloved hands, floor sample in high traffic pathway).Transfer points are not growth nichesbecause the organism is eliminated duringthe cleaning and sanitizing process.

Environmental Monitoring for Niches andTransfer PointsMonitoring for Listeria sp.• Rationale is that Listeria species survive and grow under similarconditions to L. monocytogenes.• Listeria sp. are more prevalent than L. monocytogenes.• Therefore, they are a good indicator of conditions that mightharbor or allow growth of L. monocytogenes.Objective of environmental sampling is to identifyniches and transfer points.Allowing corrective actions to be implemented.

% PositiveSurveillance of Listeria in Processing Plant302520Floors151050Packaging LinesDec Jun Dec Jun Dec Jun Dec Jun1989 1990 1991 1992From: R.B. Tompkin

Use of Sub-Typing as a ToolMolecular subtyping method• Generates a DNA fingerprint• Discrimination at the species, subspecies, or strain level• Allows for strain-to-strain comparisonUses in the food industry• Microbial source and spread tracking• Compare strains at different locations within a plant• Compare environmental isolate to finished product isolate• Niche identification

Use of Sub-Typing as a ToolPulsed-Field Gel Electrophoresis (PFGE)• Reproducibility• Ability to centralize and exchange typing data• Standardized and integrated (PulseNet, CDC)Repetitive element sequence-based PCR (rep-PCR)• Non-coding repetitive sequences found interspersed throughoutbacterial and fungal genomes• Rep elements found in all bacteria and fungi studied to date

Example of Use of Sub-Typing for TracingListeria ContaminationObjective of the study• Evaluate the discriminatory capacity of PFGE and rep-PCR to be ableto use for tracing and tracking Listeria contaminationCold smoked salmon production plant• 3 year study of Company A and Company B• Company A relocated to Company B in 3 rd yearKey findings• A specific Listeria sub-type was established before the move andfound after relocation• Environmental isolates were traced to finished product for Company A• Isolates from raw product were traced to semi-finished product(Company B)Sub-typing can be used to determine contamination routesM. ZUNABOVIC, et al, JFP Vol 75 No 3, 2012; “Monitoring Transmission Routes of Listeria spp. in SmokedSalmon Production with Repetitive Element Sequence-Based PCR Techniques”.

SummaryMany recalls due to L. monocytogenes result from post-processcontamination.Environmental monitoring for Listeria species can identify growthniches and transfer points.• Sub-typing can be a tool to traceCorrective actions to eliminate or control identified sites candramatically reduce the risk of L. monocytogenes contamination.

One more thing125 g test portion sizes for USDA samples

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