儿科英文课件化脓性脑膜炎Bacterial-meningitis

IntroductionBacterialmeningitisisaninflammationoftheleptomenings,usuallycausingbybacterialinfection.Bacterialmeningitismaypresentacutely(symptomsevolvingrapidlyover1-24hours),subacutely(symptomsevolvingover1-7days),orchronically(symptomsevolvingovermorethan1week).IntroductionAnnualincidenceinthedevelopedcountriesisapproximately5-10per100000.30000infantsandchildrendevelopbacterialmeningitisinUnitedStateseachyear.Approximately90percentofcasesoccurinchildrenduringthefirst5yearsoflife.IntroductionCasesunderage2yearsaccountforalmost75%ofallcasesandincidenceisthehighestinearlychildhoodatage6-12monthsthaninanyotherperiodoflife.Therearesignificantdifferenceintheincidenceofbacterialmeningitisbyseason.EtiologyCausativeorganismsvarywithpatientage,withthreebacteriaaccountingforoverthree-quartersofallcases:Neisseriameningitidis(meningococcus)Haemophilusinfluenzae(ifveryyoungandunvaccinated)Streptococcuspneumoniae(pneumococcus)EtiologyOtherorganismsNeonatesandinfantsatage2-3monthsEscherichiacoliB-haemolyticstreptococciStaphylococcusaureusStaphylococcusepidermidisListeriamonocytogenesEtiologyElderlyandimmunocompromisedListeriamonocytogenesGramnegativebacteriaHospital-acquiredinfectionsKlebsiellaEscherichiacoliPseudomonasStaphylococcusaureusEtiologyThemostcommonorganismsNeonatesandinfantsundertheageof2monthsEscherichiacoliPseudomonasGroupBStreptococcusStaphylococcusaureusEtiologyChildrenover2monthsHaemophilusinfluenzaetypebNeisseriameningitidisStreptococcuspneumoniaeChildrenover12yearsNeisseriameningitidisStreptococcuspneumoniaeEtiologyMajorroutesofleptomeninginfectionBacteriaaremainlyfromblood.Uncommonly,meningitisoccursbydirectextensionfromnearlyfocus(mastoiditis,sinusitis)orbydirectinvasion(dermoidsinustract,headtrauma,meningo-myelocele).PathogenesisSusceptibilityofbacterialinfectiononCNSinthechildrenImmaturityofimmunesystemsNonspecificimmuneInsufficientbarrier(Blood-brainbarrier)InsufficientcomplementactivityInsufficientchemotaxisofneutrophilsInsufficientfunctionofmonocyte-macrophagesystemBloodlevelsofdiminishedinterferon(INF)-γandinterleukin-8(IL-8)PathogenesisSusceptibilityofbacterialinfectiononCNSinthechildrenSpecificimmuneImmaturityofboththecellularandhumoralimmunesystemsInsufficientantibody-mediatedprotectionDiminishedimmunologicresponseBacterialvirulencePathogenesisAoffendingbacteriumfrombloodinvadestheleptomeninges.BacterialtoxicsandInflammatorymediatorsarereleased.BacterialtoxicsLipopolysaccharide,LPSTeichoicacidPeptidoglycanInflammatorymediatorsTumornecrosisfactor,TNFInterleukin-1,IL-1ProstaglandinE2,PGE2PathogenesisBacterialtoxicsandinflammatorymediatorscausesuppurativeinflammation.InflammatoryinfiltrationVascularpermeabilityalterTissueedemaBlood-brainbarrierdetroyThrombosisPathologyDiffusebacterialinfectionsinvolvetheleptomeninges,arachnoidmembraneandsuperficialcorticalstructures,andbrainparenchymaisalsoinflamed.Meningealexudateofvaryingthicknessisfound.Thereispurulentmaterialaroundveinsandvenoussinuses,overtheconvexityofthebrain,inthedepthsofthesulci,withinthebasalcisterns,andaroundthecerebellum,andspinalcordmaybeencasedinpus.Ventriculitis(purulentmaterialwithintheventricles)hasbeenobservedrepeatedlyinchildrenwhohavediedoftheirdisease.PathologyInvasionoftheventricularwallwithperivascularcollectionsofpurulentmaterial,lossofependymallining,andsubependymalgliosismaybenoted.Subduralempyemamayoccur.Hydrocephalusisancommoncomplicationofmeningitis.ObstructivehydrocephalusCommunicatinghydrocephalusPathologyBloodvesselwallsmayinfiltratedbyinflammatorycells.EndothelialcellinjuryVesselstenosisSecondaryischemiaandinfarctionVentricledilatationwhichensuesmaybeassociatedwithnecrosisofcerebraltissueduetotheinflammatoryprocessitselfortoocclusionofcerebralveinsorarteries.PathologyInflammatoryprocessmayresultincerebraledemaanddamageofthecerebralcortex.ConsciousdisturbanceConvulsionMotordisturbanceSensorydisturbanceMeningealirritationsignisfoundbecausethespinalnerverootisirritated.CranialnervemaybedamagedClinicalmanifestationBacterialmeningitismaypresentacutely(symptomsevolvingrapidlyover1-24hours)inmostcases.Symptomsandsignsofupperrespiratoryorgastrointestinalinfectionarefoundbeforeseveraldayswhentheclnicalmanifestationsofbacterialmeningitishappen.SomepatientsmayaccesssuddenlywithshockandDIC.ClinicalmanifestationToxicsymptomalloverthebodyHyperpyrexiaHeadachePhotophobiaPainfuleyemovementFatiguedandweakMalaise,myalgia,anorexia,Vomiting,diarrheaandabdominalpainCutaneousrashPetechiae,purpuraClinicalmanifestationClinicalmanifestationofCNSIncreasedintracranialpressureHeadacheProjectilevomitingHypertensionBradycardiaBulgingfontanelCranialsuturesdiastasisComaDecerebraterigidityCerebralherniaClinicalmanifestationClinicalmanifestationofCNSSeizuresSeizuresoccurinabout20%-30%ofchildrenwithbacterialmeningitis.Seizuresisoftenfoundinhaemophilusinfluenzaeandpneumococalinfection.Seizuresiscorrelativewiththeinflammationofbr