4细菌的感染,诊断,防治,消毒,灭菌

BacterialInfectionNormalfloraOpportunisticpathogenPathogenicbacteria(virulentbacteria)DysbacteriosisExotoxinsEndotoxinsSeparation&CultureofbacteriaBacteriemiaSepticemiaPyemiaToxemiaEndotoxemiaCarrierColonyToxoidsAntitoxinKeyWordsNotallbacteriacausedisease•Normalflora–Thenormalfloraarebacteriawhicharefoundinoronourbodiesonasemi-permanentbasiswithoutcausingdisease.–Therearemorebacterialivinginoronourbodies,thanwehavecellsofourown.Ahumanbodycontainsaround1013cells.Thehumanbodyishometoaround1014bacteria.–Onefourthoffecalweightismadeofbacteria!–Thenormalfloraareparticularlyimportantinthelargeintestine.Normalfloraarealsofoundinthenose,mouth,throat,skin.•Opportunisticbacteria–canbepartofthenormalflorabutnotpathogenicfornormalpersons,causediseaseonlyinimmunocompromisedpersons,orunderspecificconditions.•Pathogenicbacteria(virulentbacteria)–Normallynotmembersofthenormalflora,havemechanismstopromotetheirowngrowthintheexpenseofhost’stissueororgan’sfunctionThenormalfloraprotectusfromdiseaseby:1.Competingwithinvadersforspaceandnutrients.2.Producingcompounds(bacteriocins)whichkillotherbacteria.3.LoweringthepHsothatotherbacteriacan'tgrow.Inadditiontotheabovewaysofprotectingusfromdiseaseournormalflorahelpusinotherways.Ofcourse,thereisadownsideaswell...TheGoodSide•ProducevitaminsweareunabletoproducesuchasvitaminB12.•Boostourimmunesystem—Germfreeanimals(bornandraisedinagermfreeplastictent)areverysusceptibletodiseasewhenremovedfromthegermfreeenvironmentbecausetheirimmunesystemisunderdeveloped.•Helpdigestfood.TheBadSide•Ifthenormalfloraescapefromtheirnormallocation,theycancausedisease.Forexample,Escherichiacoli,commonlyfoundintheintestine,cancauseurinarytractinfectionsifintroducedintothebladder.•Immunosuppressioncanallowotherwiseharmlessbacteriatocausedisease.AIDS,somecancertreatmentsandtransplantrejectiondrugsallsuppresstheimmunesystemandallowthenormalfloratocauseoccasionallyseriousdisease.Threeconditionscorrelatewithopportunisticinfection:1.ImmuneSystemCompromise2.Dysbacteriosis3.ChangeofInhabitingPlaces:•Pathogenesisisamulti-factorialprocesswhichdependsonthenatureofthespeciesorstrain(virulencefactors),thePathwayofBacterialEntrance(gateway)andtheimmunestatusofthehost,aswellasthenumberoforganismsintheinitialexposureandtheEnvironmentalconditions.BacterialPathogenesisBACTERIALVIRULENCEFACTORS1.AdherenceFactors①Surfacehydrophobicity,②pili,③Capsule&glycocalyx④BacterialBiofilms2.InvasionofHostCells&Tissues:Enzymes3.immuneevasion:①Capsule&glycocalyx,②IgA1Proteases,③Antigenicvariation,④Interferenceofcomplementactivity⑤IntracellularpathogenicityⅠ.BacterialVirulenceFactors4.Toxins•Exotoxins•EndotoxinsExotoxinsproteinsusuallyenzymesdestroycellularstructuresdestroyextracellularmatrixAntibodies(anti-toxins)neutralize----vaccinationActiveBindingACellsurfaceBA-BtoxinsCholeratoxinandE.colilabiletoxin•ADP-ribosylationofregulator•adenylatecyclaseactivation•cyclicAMP•activeionandwatersecretion•diarrheaTetanustoxin–inhibitsglycinerelease–inactivatesinhibitoryneurons–musclesover-active–rigidparalysisNormalconditionRigidparalysis•Botulinumtoxin–inhibitsacetylcholinerelease–inhibitsnerveimpulses–musclesinactive–flacidparalysis(Acetylcholine)15Exotoxins•Antibodies(anti-toxins)neutralize–vaccinationEndotoxinsLipopolysaccharide(LPS):atoxiclipidAacorepolysaccharideOantigenpolysaccharidesidechainsCellwalllysisrequiredFormaldehydeandheatresistantPoorantigenasfreemoleculeEndotoxineffectsEndotoxineffectsFever-pyrogen1microgram/kgLeukopeniaandleukocytosisnecrosisEndotoxemiaandshockDisseminatedintravascularcoagulation(DIC).Non-specificinflammation.CytokinereleaseComplementactivationBcellmitogensPolyclonalBcellactivatorsAdjuvantsExotoxins•Toxinsproducedbybacteriaandsecretedtotheoutsideofthebacteriacell(differentfromtheendotoxin)•actingoncellsurface–Bybindingtocertainreceptors•Possesssomedegreeofhostcellspecificity•denaturedbyformaldehydetreatmenttogeneratetoxoidswhichlacktoxicactivitybutstillinduceprotectiveimmunitywhenusedasvaccines.•ManyexotoxinshaveanA-Bsubunitstructure–Asubunit--providesthetoxicactivity–Bsubunit--mediatesadherenceofthetoxincomplextoahostcellSummaryEndotoxins(LPS)derivedfromG―cellwallsandareoftenliberatedwhenthebacterialyse.heat-stable,threemainregionsatoxiclipidAacorepolysaccharideOantigenpolysaccharidesidechainsThepathophysiologiceffectsofLPSaresimilarⅡ.PathwayofBacterialEntranceContact:directorindirect(Sexualcontact)Inhalation:transmittedbytherespiratoryroute(Airbornedroplets)Ingestion:ingestedandtransmittedthroughintestinaltracttotheoutsideandgetnewinfectionsbycontaminatingoffoodandwater,whichiscalledfecal-oralspread(Food,Water)Inoculation&bloodtransfusionAnimalvectors:transmittedbyanimalvectors(insectbitting)ResponsetoInfectioninfectionxdiseaseInnateimmunityadaptiveimmunitynodisease•Immunityofextracellularbacterialinfection:antibodies(IgG,IgM,SIgA);phagocytes(neutrophils);complement;humoralimmunitymainly.•Immunityofintracellularbacterialinfection:cell-mediatedimmunity(delayed-typehypersensitivity,DTH