腸桿菌科e課件

ENTEROBACTERIACEAE.1Morphology&IdentificationGram-negativenon-sporeformingrods.Whenmotile,byperitrichousflagella.

Primarilynormalfloraofgastrointestinaltract.E.coli>Klebsiella>Proteus>Enterobacter

Freeliving,alsotransientcolonizersofskin.Facultativeanaerobes:mixedacidfermentationAllfermentglucose;allreducenitratestonitrites;alloxidasenegative.Lactosefermentation:normalflorapositiveandpathogensnegative.Primaryisolationmediaincludeeosin-methylene-blue(EMB)andMacConkeyagar.Differentialselectivemediaforspecificorganismsincludingdyesandbilesalts.(Salmonella-Shigella(SS)medium,bismuthsulfitemedia.).2Classification

~29genera,over100species.EscherichiaShigellaEdwardsiellaSalmonellaCitrobacterKlebsiellaEnterobacterHafniaSerratiaProteusProvidenciaMorganellaYersiniaErwiniaPectinobacterium.3AntigenicStructureMostaremotilebyperitrichousflagella--Hantigens.Capsule–

K

antigen(

Vi

forSalmonella).Cellenvelope(wall)LPS(endotoxin)–

O

antigen.variousoutermembraneproteins.Pili-variousantigentypes,someencodedbyplasmids

.4鞭毛抗原（H）菌體抗原(O)K或Vi抗原.5septicemia,pneumonia,meningitisurinarytractinfections

Citrobacter

EnterobacterEscherichiaHafniaMorganellaProvidenciaSerratia

Opportunisticdiseases-Enterobacteriaceae.6Enterobacteriaceae:

gastrointestinaldiseasesEscherichiacoli

Salmonella

Shigella

Yersiniaentercolitica.7Histocompatibilityantigen(HLA)B27

EnterobacteriaceaeSalmonellaShigellaYersiniaNot

Enterobacteriaceae CampylobacterChlamydiaReiter'ssyndrome.8

communityacquiredotherwisehealthypeople

Klebsiellapneumoniae

respiratorydiseasesprominentcapsuleurinarytractinfectionfecalcontamination

E.coliProteus

urease(degradesurea)alkalineurine

Enterobacteriaceae.9Enterobacteriaceaegramnegativefacultativeanaerobicrods–oxidasenegative(nocytochromeoxidase).10E.coli

lactosepositivenotusuallyidentifiedlactosepositivesp.common,healthyintestineShigella,Salmonella,Yersinia lactosenegativeidentified

Feces.11othersites

identifiedbiochemically

Enterobacteriaceae.12SerotypesreferencelaboratoryantigensO(lipopolysaccharide)H(flagellar)K(capsular).13Escherichiacoli.14EscherichiacoliToxins:twotypesofenterotoxin;Shiga-typetoxin;EnteroaggregativeST-liketoxin;Hemolysins;EndotoxinTypeIIIsecretionsystemAdhesions–colonizationfactors;bothpiliorfimbriae;non-fimbrialfactorsinvolvedinattachment.Thereareatleast21differenttypesofadhesions.Virulencefactorsthatprotectthebacteriafromhostdefenses:Capsule/Ironcapturingability(enterochelin)Outermembraneproteins.15E.colifimbriaemannoseType1

galactoseglycolipidsglycoproteinsP

.16E.coli-urinarytractinfectionIstheleadingcauseofurinarytractinfectionswhichcanleadto

acutecystitis(bladderinfection)andpyelonephritis(kidneyinfection)..17E.coli-MeningitisandSepsisNeonatalmeningitis–istheleadingcauseofneonatalmeningitisandsepticemiawithahighmortalityrate.UsuallycausedbystrainswiththeK1capsularantigen..18EnteropathogenicE.colifeverinfant

diarrheavomitingnauseanon-bloodystoolsDestructionofsurfacemicrovillilooseattachmentmediatedbybundleformingpili(Bfp);Stimulationofintracellularcalciumlevel;rearrangementofintracellularactin,.19EnterotoxigenicE.coliAwaterydiarrhea,nausea,abdominalcrampsandlow-gradefeverfor1-5days.TravellersdiarrheaanddiarrheainchildrenindevelopingcountriesTransmissionisviacontaminatedfoodorwater..20EnterotoxigenicE.colidiarrhealikecholeramildernurserytravellersdiarrheacausedbyLT,ST,orLT/ST..21EnterotoxigenicE.coli

HeatlabiletoxinlikecholeragenAdenylcyclaseactivatedcyclicAMPsecretionwater/ionsHeatstabletoxinGuanylatecyclaseactivatedcyclicGMPuptakewater/ions

.22LTvsSTactivity.23E.coli-Enteroinvasive(EIEC)TheorganismattachestotheintestinalmucosaviapiliOuter

membraneproteinsareinvolvedindirectpenetration,invasionoftheintestinalcells,anddestructionoftheintestinalmucosa.Thereislateralmovementoftheorganismfromonecelltoadjacentcells.Symptomsincludefever,severeabdominalcramps,malaise,andwaterydiarrheafollowedbyscantystoolscontainingblood,mucous,andpus.resemblesshigellosis.24EnteroinvasiveE.coli(EIEC)Dysenteryresemblesshigellosiselderchildrenandadultdiarrhea.25E.coli-c.Enteropathogenic(EPEC)Malaise

andlowgradefever

diarrhea,vomiting,nausea,non-bloodystools

Bundleformingpiliareinvolvedinattachmenttotheintestinalmucosa.Thisleadstochangesinsignaltransductioninthecells,effacementofthemicrovilli,andtointimateattachmentviaanon-fimbrialadhesioncalledintimin.Thisisaproblemmainlyinhospitalizedinfantsandindaycarecenters..26.27E.coli-d.Enterohemorrhagic(EHEC)

Hemorrhagicbloody,copiousdiarrheafewleukocytesafebrilehemolytic-uremicsyndromehemolyticanemiathrombocytopenia(lowplatelets)kidneyfailure.28EnterohemorrhagicE.coliUsuallyO157:H7Transmissionelectronmicrograph

.29EnterohemorrhagicE.coliVerotoxin“shiga-like”Hemolysinsyoungerthan5yearsold,causinghemorrhagiccolitis.30EnteroaggregativeE.coli腸集聚型大腸桿菌acauseofpersistent,waterydiarrheawithvomitinganddehydrationininfants.Thatisautoagglutinationina‘stackedbrick’arrangement.thebacteriaadherestotheintestinalmucosaandelaboratesenterotoxins(enteroaggregativeheat-stabletoxin,EAST).Theresultismucosaldamage,secretionoflargeamountsofmucus,andasecretorydiarrhea..31E.coli-Enteroaggregative(EAggEC)Mucousassociatedautoagglutininscauseaggregationofthebacteriaatthecellsurfaceandresultintheformationofamucousbiofilm.Theorganismsattachviapiliandliberateacytotoxindistinctfrom,butsimilartotheSTandLTenterotoxinsliberatedbyETEC.Symptomsinclusewaterydiarrhea,vomiting,dehydrationandoccasionalabdominalpain..32VariousTypesofE.coli.33SummaryofE.colistrainsthatcausegastroenteritis..34SanitarysignificanceTotoalbacterialnumber:numberofbacteriacontainedpermlorgmofthesample;thestandardofdrinkingwaterislessthan100.Coliformbacteriaindex:thenumberofcoliformbacteriadetectedoutper1000mlsample;thestandardofdrinkingwaterislessthan3.35EscherichiacoliGeneticallyE.coliandShigellaaregeneticallyhighlycloselyrelated.Forpracticalreasons(primarilytoavoidconfusion)theyarenotplacedinthesamegenus.Notsurprisinglythereisalotofoverlapbetweendiseasescausedbythetwoorganisms.1)EnteropathogenicE.coli(EPEC).Certainserotypesarecommonlyfoundassociatedwithinfantdiarrhea.Theuseofgeneprobeshasconfirmedthesestrainsasdifferentfromothergroupslistedbelow.Thereisacharacteristicmorphologicallesionwithdestructionofmicrovilliwithoutinvasionoftheorganismthatsuggestsadhesionisimportant.Clinicallyoneobservesfever,diarrhea,vomitingandnauseausuallywithnon-bloodystools.2)EnterotoxigenicE.coli(ETEC)producediarrhearesemblingcholerabutmuchmilderindegree.Alsocause"traveler’sdiarrhea".Twotypesofplasmid-encodedtoxinsareproduced.a)Heatlabiletoxinswhicharesimilartocholeragen(seecholerasectionbelow).AdenylcyclaseisactivatedwithproductionofcyclicAMPandincreasedsecretionofwaterandions.b)Heatstabletoxins;guanylatecyclaseisactivatedwhichinhibitsionicandwateruptakefromthegutlumen.Waterydiarrhea,feverandnausearesultinbothcases.3)EnteroinvasiveE.coli(EIEC)producedysentery(indistinguishableclinicallyfromshigellosis,seebacillarydysenterybelow).4)EnterohemorrhagicE.coli(EHEC).TheseareusuallyserotypeO157:H7.Theseorganismscanproduceahemorrhagiccolitis(characterizedbybloodyandcopiousdiarrheawithfewleukocytesinafebrilepatients).Outbreaksareoftencausedbycontaminatedhamburgermeat.Theorganismscandisseminateintothebloodstreamproducingsystemichemolytic-uremicsyndrome(hemolyticanemia,thrombocytopeniaandkidneyfailure).ProductionofVerotoxin(biochemicallysimilartoshigatoxinthusalsoknownas"shiga-like")ishighlyassociatedwiththisgroupoforganisms;encodedbyaphage.Hemolysins(plasmidencoded)arealsoimportantinpathogenesis.Asnotedabove,thereareatleast4etiologicallydistinctdiseases.However,inthediagnosticlaboratorygenerallythegroupsarenotdifferentiatedandtreatmentwouldbeonsymptomatology.Generallyfluidreplacementistheprimarytreatment.Antibioticsaregenerallynotusedexceptinseverediseaseordiseasethathasprogressedtoasystemicstage(e.g.hemolytic-uremiasyndrome).TwomajorclassesofpiliareproducedbyE.coli:mannosesensitiveandmannoseresistantpili.Theformerbindtomannosecontainingglyocoproteinsandthelattertocerebrosidesonthehostepitheliumallowingattachment.ThisaidsincolonizationbyE.coli..36Shigella.37ShigellaS.flexneri,S.boydii,S.sonnei,S.dysenteriaebacillarydysenteryshigellosisbloodyfecesintestinalpainpus.38Genralfeatures

Pili.Moststrainscannotfermentlactose;S.sonneicanslowly_fermentlactose.AccordingtoOantigen,4groupsEasilycausingdrug-resistence.

.39Shigellosiswithin2-3daysepithelialcelldamage.40Shigatoxinenterotoxiccytotoxicinhibitsproteinsynthesislysing28SrRNA.41ShigellaattachmentandpenetrationWithin2-3daysEpithelialcelldamage.42Clinicalsignificancemanonly"reservoir"mostlyyoungchildrenfecaltooralcontactchildrentoadultstransmittedbyadultfoodhandlersunwashedhands.43ClinicalsignificanceTheinfectivedoserequiredtocauseinfectionisverylow(10-200organisms).Thereisanincubationof1-7daysfollowedbyfever,cramping,abdominalpain,andwaterydiarrhea(duetothetoxin)for1-3days.Thismaybefollowedbyfrequent,scantstoolswithblood,mucous,andpus(duetoinvasionofintestinalmucosa).Isisrarefortheorganismtodisseminate.Theseverityofthediseasedependsuponthespeciesoneisinfectedwith.S.dysenteriaisthemostpathogenicfollowedbyS.flexneri,S.sonneiandS.boydii..44ImmunitySIgA..45DiagnosisofShigellainfectionSpecimen:

stool.CultureandIdentificationQuickimmunologicalmethods:Immunofluorescent“ball”test;Coagglutination..46Prevention

streptomycindependent(SD)dysenteryvaccine.

.47Treatingshigellosismanagedehydrationpatientsrespondtoantibiotics,Problemofdrug-resistancediseasedurationdiminished.48ShigellaShigella(4species;S.flexneri,S.boydii,S.sonnei,S.dysenteriae)allcausebacillarydysenteryorshigellosis,(bloodyfecesassociatedwithintestinalpain).Theorganisminvadestheepitheliallininglayer,butdoesnotpenetrate.Usually,within2-3days,dysenteryresultsfrombacteriadamagingtheepitheliumlininglayersoftheintestineoftenwithreleaseofmucusandblood(foundinthefeces)andattractionofleukocytes(alsofoundinthefecesas"pus").Shigatoxin(chromosomallyencoded)isneurotoxic,enterotoxicandcytotoxicplaysarole.Thetoxininhibitsproteinsynthesis(actingonthe80Sribosomeandlysing28SrRNA).Thisisprimarilyadiseaseofyoungchildrenoccurringbyfecal-oralcontact.Adultscancatchthisdiseasefromchildren.Howeveritcanbetransmittedbyinfectedadultfoodhandlers,contaminatingfood.Thesourceineachcaseisunwashedhands.Manistheonly"reservoir".Patientswithseveredysenteryareusuallytreatedwithantibiotics(e.g.ampicillin).Incontrasttosalmonellosis,patientsrespondtoantibiotictherapyanddiseasedurationisdiminished.

.49SalmonellaSalmonellosismaypresentasoneofseveralsyndromesincludinggastroenteritis,enteric(typhoid)feverorsepticemia..50Theantigenicstructuresofsalmonellaeusedinserologictyping.51Salmonella2000antigenic"types”diseasecategory

S.enteritidismanyserotypesS.cholerae-suisS.typhi.52VirulencefactorsEndotoxin–mayplayaroleinintracellularsurvivalCapsule(forS.typhiandsomestrainsofS.paratyphi)Adhesions–bothfimbrialandnon-fimbrialTypeIIIsecretionsystemsandeffectormolecules–2differentsystemsmaybefound:OnetypeisinvolvedinpromotingentryintointestinalepithelialcellsTheothertypeisinvolvedintheabilityofSalmonellatosurviveinsidemacrophagesOutermembraneproteins-involvedintheabilityofSalmonellatosurviveinsidemacrophagesFlagella–helpbacteriatomovethroughintestinalmucousEnterotoxin-maybeinvolvedingastroenteritisIroncapturingability.53.54EntericortyphoidfeverEntericortyphoidfeveroccurswhenthebacterialeavetheintestineandmultiplywithincellsofthereticuloendothelialsystem.Thebacteriathenre-entertheintestine,causinggastrointestinalsymptoms.Typhoidfeverhasa10-14dayincubationperiodandmaylastforseveralweeks.Salmonellatyphiisthemostcommonspeciesisolatedfromthissalmonellosis.Humanreservoir:carrierstatecommonContaminatedfood:watersupplyPoorsanitaryconditions.55Typhoidacutephase,gastroenteritisgallbladdershedding,weeksSepticemia-occurs10-14dayslasts7daysgastrointenteritis.56膽囊---腸道---糞排菌/腸壁淋巴組織腎-----尿肝脾-----腫大骨髓------受抑制皮膚----血栓出血--玫瑰疹傷寒和付傷寒的致病過程傷寒和付傷寒沙門菌小腸上部粘膜腸系膜淋巴結固有層淋巴結進入血液再次進入血液第一次菌血癥第二次菌血癥.57Typhoid-TherapyAntibioticsessentialVaccines

Vi(capsular)antigen:protective.58SalmonellagastroenteritisSalmonellagastroenteritisisthemostcommonformofsalmonellosisandgenerallyrequiresan8-48hourincubationperiodandmaylastfrom2-5days.Symptomsincludenausea,vomitinganddiarrhea(non-bloodystool).Salmonellaenteritidisisthemostcommonisolate.poultry家禽,eggs.nohumanreservoirself-limiting(2-5days).59SalmonellasepticemiaSalmonellasepticemia(bacteremia)maybecausedbyanyspeciesbutS.cholerae-suisiscommon.ThisdiseaseresemblesotherGram-negativesepticemiasandischaracterizedbyahigh,remittentfeverwithlittlegastrointestinalinvolvement..60Immunity(S.typhi)Vi(capsular)antigenprotective.61DiagnosisA.Specimensa)Entericfever:blood,bonemarrow,stool,urine.b)Foodpoisoning:stool,vomitus,suspectedfood.c)Septicemia:blood.B.CultureandidentificationC.Widaltest.62.63SalmonellaUsingappropriateantibodiesmorethan2000antigenic“types”havebeenrecognized.Thereare,however,onlyafewtypesthatarecommonlyassociatedwithcharacteristichumandiseases(mostsimplyreferredtoasS.enteritidis,S.cholerae-suisandS.typhi).Salmonellosis,thecommonsalmonellainfection,iscausedbyavarietyofserotypes(S.enteritidis)andistransmittedfromcontaminatedfood(suchaspoultryandeggs).Itdoesnothaveahumanreservoirandusuallypresentsasgastroenteritis(nausea,vomitingandnon-bloodystools).Thediseaseisusuallyself-limiting(2-5days).LikeShigellatheyinvadetheepitheliumanddonotproducesystemicinfection.Inuncomplicatedcasesofsalmonellosis,whicharethevastmajority,antibiotictherapyisnotuseful.S.cholerae-suis(seenmuchlesscommonly)causessepticemiaafterinvasion.Inthiscase,antibiotictherapyisrequired..Theseverestformofsalmonellainfections"typhoid"(entericfever),causedbySalmonellatyphi.Althoughitisoneofthehistoricalcausesofwidespreadepidemicsandstillisinthethirdworld.Theorgani