医学课件 感染汉魅hanmei-医学专区分享课件

SurgicalInfectionTengChangshengDept.ofgeneralsurgeryBeijingFriendshipHospitalAffiliatedtoCapitalUniversityofMedicalSciencesGENERALCONSIDERATIONS

Surgicalinfectionscanbedefinedasinfectionsthatrequireoperativetreatmentorresultfromoperativetreatment.

Infectionsthatrequireoperativetreatment

1.necrotizingsofttissueinfection2.bodycavityinfection3.confinedtissue,organ,stheticdevice-associatedinfections

ClassificationofSurgeryInfection一accordingtopathogenicbacterial:

1.Nonspecificinfectionstaphylococcusaureus，StreptococcusEscherichiacoli，Bacillusproteus，pseudomon.

2.Specificinfection二accordingtopathogenicprocess

1.Acuteinfection

2.Chronicinfection

3.Subacuteinfection

Infectionsthatresultfromoperativetreatmentinclude:1.woundinfection,2.postoperativeabscess3.postoperativeperitonitis4.postoperativebodycavityinfections5.hospital-acquiredinfection(resultfromthetransmissionofpathogensfromasourceinthehospitalenvironmenttoapreviouslyuninfectedpatient)suchaspneumonias,urinarytractinfection.

DeterminantsofInfection

Thedevelopmentofsurgicalinfectiondependsonseveralfactors:1.Microbialpathogenicity2.Hostdefenses,3.Thelocalenvironment4.Surgicaltechnique

MicrobialPathogenicity1.Thickcapsules2.Resistdigestionbylysosomalenzymes.

3.Elaboratetoxins:endotoxins,neurotoxinsLocalEnvironmentalFactorsLocalenvironmentalfactorsinhibitsystemichostdefensesfrombeingfullyeffective:DevitalizationoftissueForeignbodiesDiagnosisDiagnosisofsurgicalinfectionshouldbeaccordedtoclinicalexaminationandlaboratoryexamination.ClinicalExamination1.Systemicsymptoms:FeverandChillsElevatedpulserate2.Endemicsignsandsymptoms:RednessSwellingHeatPainLossoffunction.3.shock,dysfunctionoforgans4.SpecialmanifestationLaboratoryExamination

1.Bloodroutineexamination

Leukocytosis:whitecellcount>10000/mlimmaturegranulocytes>85%.2.ExudateExaminationExudateshouldbeexaminedbymacroandmicromethodPhysicalnature:color,odor,consistency3.Bloodculture

Itisthesinglemostdefinitivemethodofdeterminingetiologyininfectiousdisease.Thelaboratoryshouldberequestedtodoaerobicandanaerobicculturesandantibiotic-sensitivitytests.Whenshouldwetakeabloodculture?

PrincipleofTherapyTheaimofprincipleoftherapyistoinhibitbacterialproliferationandpromotebodytissuerecurrence.Thepatient’sownhostdefensesandantibiotictherapyareadequatetoovercomemostinfections(1)

Endemictreatment

ImmobilizationofinfectiveareaandhavearestMedicinesPhysicaltherapyOperationOperativetreatmentinclude:

incisinganddraininganabscessopeninganinfectedwoundremovinganinfectedforeignbodyrepairingordivertingabowelleakdraininganintra-abdominalabscessSystemictreatmentItapplyforsevereinfectionespeciallysystemicinfection.Methodsinclude:supporttreatment,antibioticsandoperation.TYPESOFSURGICALINFECTIONS

SoftTissueInfections:Infectionofthesofttissues,skin,subcutaneousfat,fascia,andmuscle,usuallycanbetreatedbyantibioticsunlessanabscessispresentortissuenecrosisispresent.

CellulitisCellulitisisaspreadinginfectionoftheskinandsubcutaneoustissues.Itischaracterizedbylocalpainandtenderness,edema,anderythema.UsuallytheborderbetweeninfectedanduninvolvedskinisindistinctCellulitisandlymphangitiscanbetreatedbyantibioticsalone.Localcareincludesimmobilizationandelevationtoreducepainandswelling.Failuretoachievepromptclinicalresponseshouldsuggestthatsuppurationhasoccurredandthatsurgicaldrainageisrequired.

Erysipelas

Erysipelasisanacutespreadingcellulitisandlymphangitis,usuallycausedbyhemolyticstrepotococcuswhichgainentrancethroughabreakintheskin.Characteristics:abruptonset,chills,fever,andprostration.Theskinisred,swollen,andtender,andthereisadistinctlineAbscessandFuruncleAnabscessislocalizedcollectionofpussurroundedbyanareaofinflamedtissueinwhichhypermiaandinfiltrationofleukocytesismarked.Afuruncleisanabscessinasweatglandorhairfollicle.Theinflammatoryreactionisintense,leadingtotissuenecrosisandtheformationofacentralcore.Thisissurroundedbyaperipheralzoneofcellulitis.Carbuncle

Acarbuncleisamultilocularsuppurativeextensionofafuruncleintothesubcutaneoustissue.Thenapeoftheneck,dorsumoftrunk,handsanddigits,andhirsuteportionsofthechestandabdomenareapttobeinvolved.Individualcompartmentsinacarbunclearemaintainedthroughpersistenceoffascialattachmentstotheskin.Asthesenumerouscomponentloculesruptureseparately,individualfistulasappear.NecrotizingSoftTissueInfections

Softtissueinfectionthatresultintissuenecrosisarelesscommonthanotherformsofsofttissueinfectionsbutaremoreseriousbecauseoftheirpropensityforextensivedestructionoftissuesandhighmortalityrate.Namessuchasnecrotizingfasciitis,streptococcalgangrene,bacterialsynergisticgangrene,clostridialmyonecrosis,andFournier`sgangrenearecommonlyused.Differentiatetheseinfectionsarebasedonpredisposingconditions,presenceofpain,toxicity,fever,presenceofcrepitus,appearanceoftheskinandsubcutaneoustissues,andwhetherornotbullaearepresent.Necrotizingfasciitisisrarelylimitedtofasciaandmyonecrosisisrarelylimitedtomuscle.

Pathogenicbacterial

Mostnecrotizingsofttissueinfectionarecausedbymixedaerobicandanaerobicgram-negativeandgram-positivebacteria.Clostridiumspeciesarethemostcommon,causethemostdramaticinfectionswithrapidprogression,earlytoxicity,andhighmortalityrate.ManifestationandDiagnosisskinnecrosisorbullaecrepitusEarlymentalconfusion,toxicity,andfailuretorespondtononoperativetherapyTreatmentSurgicaltreatmentrequiresdebridementofallnecrotictissue.Allnecrotictissuemustberemoved.Amputationmayberequiredformyonecrosisoftheextremities.Thewoundmustbeinspecteddailyuntilthesurgeoncanbesurethereisnofurthernecrosis.

Initially,broad-spectrumantibioticsshouldbeadministered.HyperbaricOxygenTreatment

Theuseofhyperbaricoxygentotreatnecrotizingsofttissueinfectionsiscontroversial.Hyperbaricoxygeninhibitsproductionofalphatoxinbyclostridium.TetanusTetanusiscausedbyC.tetani,alargegram-positivesporeformingbacillus.Itisacquiredbyimplantationoftheorganismsintotissuesbymeansofbreaksinthemucosalorskinbarriers.ActionofC.tetaniC.tetanielaborates:tetanospasmintetanolysin.Tetanospasminactsontheanteriorhorncellsofthespinalcordandonthebrainstem.Itblocksinhibitorsynapsesatthesesites,leadingtomusclespasmsandhyperreflexia.TetanolysiniscardiotoxicandcauseshemolysisManifestationofTetanusSymptoms:restlessness,headache,musclespasmswithvaguediscomfortintheneck,lumbarregion,andjaws,swallowingdifficult,stiffneckProgressively,Orthotonos,opisthotonos,andemprosthotonos,Generalizedtoxicconvulsions.Theseconvulsionsmayinvolvethelaryngealandrespiratorymusclesandresultinfatalacuteasphyxia.

Othersymptom:Throughoutthesespasms,whichcanbeextremelypainfulandevencausefractures,thepatientremainsmentallyalert.Thepulseiselevatedandthereisprofuseperspiration.Fevermayormaynotbepresent.

DiagnosisDiagnosisoftetanusisbasedontheclinicalpictureassociatedwithnopriorhistoryofimmunization.Thedifferentialdiagnosiscanbedifficultinearlytetanus.Evenwithadequatetreatment.

TreatmentPatientsrequireexquisitenursingcareandshouldbemonitored.Initiallytherapyconsistofadministrationoftetanusimmuneglobulin(TIG),500to10,000units,assoonasthediagnosisismade.Currentlymostaretreatedinanintensivecareunitonarespiratorwithparalyticdrugsgiventopreventmusclespasms.

Mildcasescanbetreatedwithsedation,butmostphysiciansadministermusclerelaxants.Adequatedosesofanalgesicsarerequiredbecauseofthepainassociatedwithmusclespasms.Detailedattentionmustbegiventocareaparalyzedindividualwhoisonarespirator.Adequatenutritionmustbeprovided.Laxativesaregenerallyindicatedsothatgastro-intestinaleliminationcanbefacilitated.Aurinarycathetershouldbeprovided.Thepatientwillrequireeyeprotectiontopreventdesiccation.

ThewoundmustbetreatedtoremoveasmuchoftheC.tetaniandnonviolabletissueaspossible.Debridementofallnecrotictissueshouldbedone.PenicillinGshouldbeadministeredtotreatanybacteriathatremainbehind,butantibioticsarenosubstituteforgoodwoundcare.

Prevention.Activeimmunizationwithtetanustoxoid(TD)isasafeandeffectivewayofpreventingtetanus.UnfortunatelymanychildrenintheUnitedStatesarenotadequatelyvaccinated;immunizationisalsoinadequateinmanydevelopingcountries.Onemonthafterthediagnosisoftetanusismade,thepatientshouldbebegunontetanustoxoidimmunization.Thedoseoftetanustoxinmediatedduringaninfectionissosmallthatimmunizationdoesnotoccur.

BacteremiaBacteremiaisdefinedasbacteriainthecirculatingbloodwithnoindicationoftoxemiaorotherclinicalmanifestations.Bacteremiaisusuallytransientandmaylastonlyafewmoments,Intoxemia,toxinsarecirculatingintheblood,thoughthemicroorganismproducingthetoxinneednotbe.Toxemiaisusuallyassociatedwithinfectionbytoxin-producingbacteria(e.g.,theclostridiaofgasgangreneandthediphtheriabacillus),butthisisnotalwaysso.Forexample,botulinumtoxinorstaphylococcalenterotoxinmayhavebeeningesteddirectlytocauseaprofoundtoxemiawithouttrueinfection.

SepticemiaSepticemiaisadiffuseinfectionwhichinfectiousbacteriaandtheirtoxinsarepresentinthebloodstream.Septicemiamayarisedirectlyfromtheintroductionofinfectingotganismsintothecirculationbut,asarule,issecondarytoafocusofinfectionwithinthebody.Themajorroutesbywhichbacteriareachthebloodare(1)bydirectextensionandentranceintoanopenvessel.(2)byreleaseofinfectedembolifollowingthrombosisofabloodvesselinanareaofinflammation,(3)bydischargeofinfectedlymphintothebloodstreamfollowinglymphangitis.Manyspecificdiseases,e.g.,typhoidfeverandbrucellosis,includeasepticemicphase.Intheabsenceofsystemicdisease,beta-hemolyticstreptococciaremostfrequentlyresponsible.Septicemiacausedbyalpha-hemolyticstreptococciisusuallyaconsequenceofsubacutebacteriaendocarditis.Themajorityofbacteriathatproducesuppurativelesionsmaygiverisetosecondarysepticemia.Pyemiaissepticemiainwhichpyogenicmicroorganisms,mostnotablystaphylococcusaureus,andtheirtoxinsarecarriedinthebloodstreamandsequentiallyinitiatemultiplefocalabscessinmanypartsofthebody.Beforetheadventofchemotherapy,staphylococcicpyemiawasalmostalwaysfatal;themortalityisstillhigh..ANTIMICROBIALTHERAPY

Theuseofantimicrobialsintreatingsurgeryinfectionsdoesnotdifferfundamentallyfromantimicrobialusageingeneralmedicine.Thesamebasicconsiderationsapplyintreatingallinfections.Onedifference,however,isthatantimicrobialtherapyisonlyanadjunctintreatingsurgicalinfection;operativetreatmentisthemainmethodoftherapy.Thegoalofantomicrobialtherapyistopreventortreatinfectionbyreducingoreliminatingpathogenicorganismsuntilthehost’sowndefensescangetridofthelastpathogens.

Thebasicconsiderationinantimicrobialtherapyareefficacy,toxicity,andcost.Effectivenessisthemostimportantconsiderationinchoosingantimicrobialtherapy.Effectiveantimicrobialagentsmustbeactiveagainstthepathogenstheinfectionandmustbeabletoreachthesiteofinfectioninadequateconcentrations.

Allantibioticshavepotentialtoxicity.Toxiceffectsmaybeidiosyn-craticsuchasallergyortherareinstanceofbonemarrowaplasiacausedbychloramphenicolorresultindamagetotissueandorgansasrenalorototoxicityseenwiththeaminoglycosidesoramphotericinB.Antimicrobialagentsalsoexertselectivepressuresonthemicrobialecologyofthehospitalthatleadtoresistantmicrobes,aproblemthatcanoccurespeciallyinintensivecareunitsettings.

Costisthefinalconsiderationintheselectionofantimicrobialagents.Determiningantimicrobialcostsincludes,nursingtime,intravenousfluidandlines,andmonitoringcostsmustalsobeaddedtodrugcosts.Theincreasedhospitaltimethatoccurswhenaninexpensivebutalsolesseffectiveagentisusedshouldalsobeincludedincosts.Obviouslyaninexpensiveagentthatisnoteffectiveorthatcausesmoretoxicityultimatelybecomesamoreexpensiveantimicrobial.

DistributionofAntimicrobialAgents

Successfultreatmentoflocalizedinfectionswithsystemicantimicrobialagentsrequiresthatanadequateconcentrationofdrugbedeliveredtothesiteofinfection.Ideallythetissueconcentrationofantibioticsshouldexceedtheminimuminhibitoryconcentration.Tissuepenetrationdependsinpartonproteinbindingofantibiotics.Onlytheunboundformofantibioticswillpassthroughthecapillarywalloracttoinhibitbacterialgrowth.Therapeuticoutcome,ontheotherhand,appearsuncorrelatedwithproteinaffinity,presumablybecauseproteinbindingiseasilyreversible.Lipidsolubilityofantibioticsisalsoanimportantfactorintissuepenetration.itdeterminestheabilityofantibioticstopassthroughmembranesbynonionicdiffusionorintowounds,bone,cerebrospinalfluid,theeye,endolymphoftheear,vegetationofbacterialendocarditis,andabscesses.

Blood.Rapidityofexcretionandproteinbindingaretwomaindeterminantsofbloodconcentrationofantimicrobialagents.Proteinbindingaffectstherapidityofexcretion.Antibioticsthatarehighlyproteinboundarenotexcretedasrapidlyasthosewithalowbindingaffinityandthushavelongerhalf-lives.Therefore,highlyproteinboundantibioticsgenerallydonothavetobegivenasfrequentlyasthosewithlowproteinbinding.Efficacyofpenicillins,cephalosporins,andotherantibioticsthataffectbacterialcellwallsynthesisdependsonthetimeduringwhichserumlevelsareabovetheminimuminhibitoryconcentra-tionsratherthanapeakserumconcentration.Efficacyofaminoglycosides,ontheotherhand,isrelatedtoachievingpeakserumconcentrationsthatarefourtoeighttimestheminimuminhibitoryconcentration.Monitoringofserumaminoglycosideconcentrationisusuallynecessarytoensurethattheseconcentrationhavebeenachieved;patientsmorecommonlyhavesubtherapeuticlevelsratherthantoxiclevels.Ontheotherhand,someantimicro-bialagentssuchasnitrofurantoinandnorfloxacinarerapidlyintheurinethattheyneverachievebloodlevelssufficienttoachieveeffectiveantibacterialconcentrations.Theydo,however,reachhighurinaryconcentrationsandareeffectiveagentsfortreatingurinarytractinfections.

urine.Mostcommonlyusedantibiotics(sulfonamides,penicillins,cephalosporins,aminoglycosides,tetracyclines,quinolones,azoles)areexcretedprincipallyintheurineandachievehighurinaryconcentrations—upto50to200timestheirserumconcentration.Notableexceptionsareerythromycinandchloramphenicol.Sinceconcentratingabilityisseverelycompromisedinpatientswithrenaldisease,infectionsoftheurinarytractaremoredifficulttotreatinthesepatients.ThepHofurinecanbechangedtofacilitateantibioticactivity.Forinstanceaminoglycosidesaremoreactiveinanalkalinemedium,whereasotherurinaryantibacterialagentsaremoreactiveinanacidicenvironment.Fortunately,theantimicrobialsmostcommonlyusedtotreaturinarytractinfectionshaveantimicrobialactivityacrossabroadpHrange.

Bile.Besidesurine,onlybileregularlyhasconcentra-tionsofantibioticshigherthanfoundinserum.Thebiliaryconcentrationsofmanyofthepenicillinsespeciallynafcillin,piperacillinmezlocillin,andazlocillin;cephalosporinsespeciallycefazolin,cefadroxil;tetracyclines;andclindamycinfrequentlyareseveraltimestheirserumcontractions.Nafcillinandrifampinachievebiliaryconcentrations20to100timesthatofserum.Aminoglycosideantibioticsenterbilelesswell,especiallyinthepresenceofliverdisease.Theirbiliaryconcentrationsareusuallylowerthanserumlevels.

InterstitialFluidandTissue.High,prolongedserumconcentrationandlowproteinbindingfavordiffusionofantibioticsfromserumintoextravasculartissue.Absolutetissuelevelsmaynotaccuratelyreflectthetherapeuticoftheantibiotic,however,becausetheagentmaybetightlyboundtotissueandthusbeunavailableforbindingtobacteria.

Abscesses.Therearefewdateofclinicalrelevanceconcerningthedistributionofantibioticsintoabscesses.Thegeneralizationthatnoantibioticspenetrateabscessesisnottrue.Whilethepenicillins,ephalosporins,andsomeotherantibioticspenetratematureabscessespoorly,otherssuchasmetronidazole,chloramphenicol,andclindamycinanachieveinhibitoryconcentrationsinabscesses.

Aseparateproblemiswhether,afterpenetration,antibioticretainitsantimicrobialefficacyundertheconditionsthatexistinanabscess.TheacidicpH,lowredoxpotential,andthelargenumbersofmicrobialandtissueproductsthatcanbindantibioticsallservetoreduceantimicrobialefficacy.Multipletypesofbacteriawithinanabscessmakeitmorelikelythatonetypewillinactivateanagenteffectiveagainstitoranotherbacteria.Thelackofefficacyofpenicillinsandcephalosporinsintreatingmostabscessmaybeduetohighconcentrationsofbetallactamasesthataccumulatethere.Metronidazoleandclindamycincanbothenterabscessesandretainantibacterialactivityinsuchenvironments.buttheseantibioticsarenoteffectiveagainsttheaerobicgram-negativebacteriathatareusuallypresenttogetherwiththeanaerobicbacteriaagainstwhichtheyareeffective,sotheabscessusuallypersists.

Anadditionalreasonthatantibioticsaloneareseldomeffectiveintreatingabscessesisthatantibioticsaremosteffectiveagainstactivelymetabolizing,rapidlydividingbacteria.Conditionsinabscessesareusuallyunfavorableforsuchactivemetabolicactivity,sotheantibioticsisnotabletoenterandbeactiveagainstthebacteria.

Forallthesereasonsantibioticsaloneshouldnotbereliedontotreatmostabscesses.Despiteoccasionalreportsofsuccesswithsuchtreatment,drainageremainsthemainstayofabscesstreatment.

UseofAntibioticsinSurgery

Prophylacticantibiotics.Antibioticsarefrequentlyadministeredprophylacticallytopatientsundergoingoperationtopreventwoundinfectionwherethelikelihoodofinfectionishigh(whenthetissuehavebeenexposedtobacteriasuchasoccursduringcolonsurgery)orwheretheconsequencesofinfectionaregreateventhoughtheriskofinfectionislow.Antibioticprophylaxisshouldalsobeadministeredtomanypatientswithpreviouslyplacedprostheticdevicessuchascardiacvalveswhoarehavingoperationsordentalprocedures.

TherapeuticUseofAntibiotics.Manyinfectionscanbesuccessfullytreatedwithoralantibioticsonanoutpatientbasis.Severesurgicalinfectionsshouldbetreatedwithintravenousantibiotics.Initialantibiotictherapyisusuallyempiricsinceitshouldbepostponeduntilmicrobiologicstudiesarecomplete.Antibiotictherapyshouldgenerallybeinitiatedbeforeculturesareobtainedwithperitonitis,abscesses,andnecrotizingsofttissueinfections.Sinceculturesareusuallyobtainedpromptlyduringoperativeproceduresorwhenpercutaneousdrainagehasbeenpreformed,itisunlikelythatpriorantibiotictherapywillaffectcultureresultsformostsurgicalinfections.

EmpiricTherapy

Rationalempiricantibiotictherapyrequiresfamiliaritywiththemicrobesmostlikelytocauseinfectionattheinvolvedsiteandantibioticsusceptibilitypatternsinthehospitalorunit.Intraabdominalsurgicalinfectionsarevirtuallycausedbymixedgram-negativeandgram-positiveaerobicandanaerobicbacteria.Initialantibiotictherapyshouldprovidebroad-spectrumactivityagainstthesebacteria

Mostnecrotizingsofttissueinfections,especiallythoseoriginatingafteranintraabdominaloperationoroccurringbelowthewaist,arealsoduetoamixedbacteriaflora,andbroad-spectrumempirictherapyshouldbeinitiated.Becauseclostridiaorstreptococcitherapycanalsocausetheseinfections,penicillinGshouldgenerallybeincluded.OnceGramstainandcultureresultsareavailable,antibiotictherapycanbemodified.

Prostheticdeviceinfectionsusuallyprogressmuchmoreslowlythanintraabdominalornecrotizingsofttissueinfections.Gram-positivecocci,especiallyS.aureusandS.epidermidis,playaprominentroleintheseinfections,buttheycanalsobecausedbygram-negativebacteria.

Numeroussingleandcombinationantimicrobialsareavailableforinitialandimperativetherapy.TheSurgeryInfectionSociety(SIS)hasmaderecommendationsforantimicrobialsthatcanbeusedforempiricherapyofintraabdominalinfections.Theyrecommendagainstusingdrugascefazolinandotherfirst-generationcephalosporins,penicillin,cloxacillinandotherantistaphylococcalpenicillins,ampicillin,erythomycin,andvancomycinbecausethesedrugsdonotprovideadequatecoverageforbothaerobicandanaerobicorganisms.

MetronidazoleandclindamycinshouldnotbeusedassingleagentsbecausetheylackactivityagainstentericorganismsOtherantibiotics,suchasaminoglycosides,aztreonam,cefuroxime,cefonicid,Cefamandoie,ceforanide,cefotetan,cefitaxime,cefopeyazone,ceftriaxone,ceftazidime,andpolymyxinshouldnotbeusedalonebecauseoftheinadequatecoverageofanaerobicgram-negativebacilli.Becauseofinadequateclinicaldatadocumentingefficacyandconcernsaboutresistance,theSISalsorecommendsagainstusingassingleagentsforempirictherapyantibioticssuchaspiperacillin,mezlocillin,azlocillin,ticarcillin,andcsrbenicillindespitetheirrelativesafetyazlocillin,ticarcillin,ticarcillin,andcarbenicillindespitetheirrelativesafetyinbroadinvitroantibacterialactivityChloramphenicolhasanappropriateinvitrospectrumofactivitybutisnotacceptablebecauseitproducesserioussideeffects.

Acceptableagentsforcommunity-acquiredintr