医学课件 感染-【汉魅HanMei-医学专区分享】

SurgicalInfectionTengChangshengDept.ofgeneralsurgeryBeijingFriendshipHospitalAffiliatedtoCapitalUniversityofMedicalSciencesGENERALCONSIDERATIONS

Surgicalinfectionscanbedefinedasinfectionsthatrequireoperativetreatmentorresultfromoperativetreatment.

Infectionsthatrequireoperativetreatment

1.necrotizingsofttissueinfection2.bodycavityinfection3.confinedtissue,organ,andjointinfection4.prostheticdevice-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,neurotoxinsHostDefenses

LocalHostDefenses.1.Epithelium.2.Localenvironmentisnotconducivetomicrobialattachmentandgrowth.SystemicHostDefenses

Hostdefenses:Phagocyticcells:polymorpho-nuclearleukocytes(PMNs)tissuemacrophages.ImmunesystemMolecularcascades.

Theinitiationofthisprocessanditsattendantchemical,cellular,andphysiologicchangesresultsininflammation.

LocalEnvironmentalFactorsLocalenvironmentalfactorsinhibitsystemichostdefensesfrombeingfullyeffective:DevitalizationoftissueForeignbodiesDiagnosisDiagnosisofsurgicalinfectionshouldbeaccordedtoclinicalexaminationandlaboratoryexamination.ClinicalExamination1.Systemicsymptoms:FeverandChillsElevatedpulserate2.Endemicsignsandsymptoms:RednessSwellingHeatPainLossoffunction.3.shock,dysfunctionoforgans4.Specialmanifestation5.HistoryLaboratoryExamination

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.

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-acquiredintraabdo-minalinfectionsincludecefoxitincefotetan,cefmetazole,andticarcillin/clavulanicacidHowever,theseantinioticsshouldnotbeusedforpatientswhoseabdominalinfectiondevelopsinthehospitalafterpreviousantibiotictherapyFortheseinfectionsandseriousintraabdominalinfectialinfectionsimipenem-cilastatin(Primaxin)shou;dbeusedCombinationtherapysuchasmetronidazoleorclindamycinplusanaminoglycosideoranantianaerobicantibacterialagentplusathirdgenerationcephalosporinorclindamycinplusamonobactamisacceptable.CostconsiderderationandtoxicityconsiderationmakeoneoftheserecommendationspreferabletoanotherThecomb