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RongWang,Ph.D. U.S.MeatAnimalResearchCenter AgriculturalResearchService UnitedStatesDepartmentofAgriculture ClayCenter,NE68933 Salmonellaenterica Adiversegroupofbacteriawithover2,500serotypes identified; Only20Salmonella serotypesaccountformorethan70%of humansalmonellosis cases,mainlyassociatedwiththe consumptionofcontaminatedfoodsincludingredmeat; SerotypesAnatum andMontevideoarecommonlyisolated fromcontaminatedmeatproducts,whileNewportand Typhimurium areobservedlessfrequently; CertainSalmonella serotypesorstrainsaremorecapableof causingmeatcontaminationincommercialplants? Somecontamination“Events”(STECO157:H7) contradictwiththetraditionalmodel Transferofincomingpathogensfromhidestocarcassesduringprocessing Strainsisolatedfromproductswouldbeadirectresultofcontamination onhidesandalsoreflectthehighgeneticdiversity StrainsfromhidesHEPstrainswithinan“Event” Surfacecolonization&Sanitizerresistance O157“Event”strainshad significantlystrongerbiofilm formingabilityandhigher sanitizerresistancecomparedto thecontrolstrains; “…….E.colifoundoncutsand trimmings……..mainlyoriginated fromtheconveyorbeltandthat smallnumberofE.colistrains survivedthedailycleaningand sanitationprocess,thuspersisting intheplant.” Biofilm formation&sanitizationresistancecontribute toproductcontaminationbySalmonellaenterica? Biofilms maybefoundoncontactsurfaces,equipmentorother areasinfoodprocessingenvironment; Biofilm formationenhancesbacterialresistancetosanitizers. Salmonellaenterica strainsfromtrimand post‐interventioncarcasses(FSIS) Cell surface structures • 57 (64%) strains positive for cellulose expression; Celluloseexpressionon Fluorescentbrightener plates • 80 (90%) strains positive for curli expression Curli expressiononCongoredplates • • Atotalof89strains&21serotypesidentified; Anatum,Dublin,Montevideo,Typhimurium; Biofilm formationoncommoncontactsurfaces Stainlesssteelor P.V.Cplasticsurfaces @7oCfor5days; Rinse,sonicate &vortex withglassbeads Colonyenumeration (Log10CFU/cm2)on X.L.Dagarplates Salmonella controlstrainsfromvariousresources (hides,fecalswabs,pre‐carcass,humaninfections): Anatum,Cerro,Dublin,Montevideo,Newport,Typhimurium. Biofilm formationoncommoncontactsurfaces StainlessSteel P.V.CPlastic Biofilm Detectionon96‐wellplates withCrystalVioletstaining(O.D570nm) 3days@22– 25oC Sanitizerresistance&Recoverygrowth Sanitizer: Chlorine:200ppm Chlorinedioxide:50ppm Quaternaryammonium chloride(QAC):300ppm Absorbanceassay(405/590 nm)measuringbacterial growthinDey/Engley neutralizingbrothafter sanitization. Biofilm cellstransferfromcontact surfacetomeatproducts S.SorP.V.C 7oCfor5days; 30seccontacttime 15consecutivesamples Vigorousagitation Strong&weakbiofilm formers S.S&P.V.C Muscle&fattissue Enumerationon X.L.Dplates Overnightenrichment@ 37oCforSalmonella prevalenceconfirmation Effectsofbiofilm potencyandcontactsurface materialsonbacterialtransferefficiency Biofilm formingabilityandcontactsurfacematerials(S.S>P.V.C) hadsignificanteffectonSalmonellabiofilm celltransferefficiency. Meatsurfacetissuetypeshadnosignificant effectontransferefficiency Allmeatsamples(non‐enumerable)exhibitedpositive Salmonellaprevalenceafterenrichment. Summary AhighpercentageofSalmonella strainsisolatedfromtrim/ post‐interventioncarcasseswerestrongbiofilm formers; Biofilm cellsexhibitedhighresistancetosanitizerscommonly usedinmeatprocessingplants; Salmonella cellsinbiofilms couldbetransferredefficientlyto meatsurfacemultipletimesviadirect/briefcontact; Biofilm formingabilityandcontactsurfacematerialshad significanteffectsonbacterialtransferefficiency; Allmeatsamplesincontactwithsolidsurfacescolonizedby Salmonella biofilms hadpositiveSalmonella prevalence; Biofilm formationbySalmonellaenterica mightpresenta seriousriskofcausingcross‐contaminationinmeatplants. Acknowledgements USMARC: NAMIFoundation: Dr.TerranceArthur MichelleRossman Dr.DaynaHarhay Dr.AndyKing AlbertoO.Alvarado BruceJasch FSIS: Dr.JohnJohnston Researchsupportedby: