Download Rong Wang, Ph.D. U.S. Meat Animal Research Center Agricultural

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/
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
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: