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1、EnterobacteriaceaeMLAB2434–MicrobiologyKeriBrophy-MartinezOverview-EntericsFamilyEnterobacteriaceaeoftenreferredtoas“enterics”Fourmajorfeatures:Allfermentglucose(dextrose)AllreducenitratestonitritesAllareoxidasenegative,exceptPlesiomonasAllexceptKlebsiell
2、a,ShigellaandYersiniaaremotileMicroscopicandColonyMorphologyGramnegativebacilliorcoccobacilliNon-sporeformingFacultativeanaerobeColonymorphologyonBAPorCAoflittlevalue,astheylookthesamelarge,moistandgreyonSBASelectiveanddifferentialmediaareusedforinitialco
3、lonyevaluationex.MacConkey,HE,XLDagarsClassificationofEntericsDuetotheverylargenumberoforganismsintheFamilyEnterobacteriaceae(seeTable19-1,page429),speciesaregroupedintoTribes,whichhavesimilarcharacteristicsWithineachTribe,speciesarefurthersubgroupedunder
4、generaVirulenceandAntigenicFactorsofEntericsAbilitytocolonize,adhere,producevarioustoxinsandinvadetissuesSomepossessplasmidsthatmaymediateresistancetoantibioticsESBL’s:Extended-SpectrumbetalactamasesInactivateextendedspectrumantibioticslikepenicillins,cep
5、halosporinsandaztreonamVirulenceandAntigenicFactorsofEntericsManyentericspossessantigensthatcanbeusedtoidentifygroupsOantigen–somatic,heat-stableantigenlocatedinthecellwall,madebyallbacteria,stimulatesEARLYantibodyproductionHantigen–flagellar,madebybacter
6、iawithflagella,heatlabileantigen,stimulatesLATEantibodyproductionKantigen–capsular,heat-labileantigen,madebysomebacteriaVi-capsularantigenofS.typhiiClinicalSignificanceofEntericsEntericsareubiquitousinnatureExceptforfew,mostarepresentintheintestinaltracto
7、fanimalsandhumansascommensalflora;therefore,theyaresometimescall“fecalcoliforms”Someliveinwater,soilandsewageClinicalSignificanceofEnterics(cont’d)Basedonclinicalinfectionsproduced,entericsaredividedintotwocategories:Opportunisticpathogens–normallypartoft
8、heusualintestinalflorathatmayproduceinfectionoutsidetheintestinePrimaryintestinalpathogens–notcommensalflora,theyproduceinfectionfromingestionofcontaminatedfoodorwater(Salmonella,Shigella,andYersiniasp.)Escherichiac
