SIBO syndromeWord下载.docx

SIBO syndromeWord下载.docx

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MiroslavFö

rstl,InstituteofClinicalMicrobiology,CharlesUniversityinPraha,FacultyofMedicineatHradecKralove,UniversityTeachingHospital,Sokolska581,50005HradecKralove,CzechRepublic

JaroslavKvetina,InstituteofExperimentalBiopharmaceutics,JointResearchCentreofCzechAcademyofSciencesandPRO.MED.CSPrahaa.s.,Heyrovskeho1207,50003HradecKralove,CzechRepublic

ViktorVorisek,InstituteofClinicalBiochemistryandDiagnostics,CharlesUniversityinPraha,FacultyofMedicineatHradecKralove,UniversityTeachingHospital,Sokolska581,50005HradecKralove,CzechRepublic

Authorcontributions:

BuresJ,CyranyJ,KohoutovaD,Fö

rstlM,RejchrtS,KvetinaJ,VorisekVandKopacovaMcontributedequallytothiswork.

SupportedbyTheResearchProjectMZO00179906fromtheMinistryofHealth,CzechRepublic,andbyResearchGrantGACR305/08/0535,CzechRepublic

Correspondenceto:

JanBures,Professor,MD,PhD,2ndDepartmentofMedicine,CharlesUniversityinPraha,FacultyofMedicineatHradecKralove,UniversityTeachingHospital,Sokolska581,50005HradecKralove,

CzechRepublic.bures@lfhk.cuni.cz

Telephone:

+420-495-834240Fax:

+420-495-834785

Abstract

Humanintestinalmicrobiotacreateacomplexpolymicrobialecology.Thisischaracterisedbyitshighpopulationdensity,widediversityandcomplexityofinteraction.Anydysbalanceofthiscomplexintestinalmicrobiome,bothqualitativeandquantitative,mighthaveserioushealthconsequenceforamacro-organism,includingsmallintestinalbacterialovergrowthsyndrome（SIBO）.SIBOisdefinedasanincreaseinthenumberand/oralterationinthetypeofbacteriaintheuppergastrointestinaltract.Thereareseveralendogenousdefencemechanismsforpreventingbacterialovergrowth:

gastricacidsecretion,intestinalmotility,intactileo-caecalvalve,immunoglobulinswithinintestinalsecretionandbacteriostaticpropertiesofpancreaticandbiliarysecretion.AetiologyofSIBOisusuallycomplex,associatedwithdisordersofprotectiveantibacterialmechanisms（e.g.achlorhydria,pancreaticexocrineinsufficiency,immunodeficiencysyndromes）,anatomicalabnormalities（e.g.smallintestinalobstruction,diverticula,fistulae,surgicalblindloop,previousileo-caecalresections）and/ormotilitydisorders（e.g.scleroderma,autonomicneuropathyindiabetesmellitus,post-radiationenteropathy,smallintestinalpseudo-obstruction）.Insomepatientsmorethanonefactormaybeinvolved.SymptomsrelatedtoSIBOarebloating,diarrhoea,malabsorption,weightlossandmalnutrition.ThegoldstandardfordiagnosingSIBOisstillmicrobialinvestigationofjejunalaspirates.Non-invasivehydrogenandmethanebreathtestsaremostcommonlyusedforthediagnosisofSIBOusingglucoseorlactulose.TherapyforSIBOmustbecomplex,addressingallcauses,symptomsandcomplications,andfullyindividualised.Itshouldincludetreatmentoftheunderlyingdisease,nutritionalsupportandcyclicalgastro-intestinalselectiveantibiotics.Prognosisisusuallyserious,determinedmostlybytheunderlyingdiseasethatledtoSIBO.

©

2010Baishideng.Allrightsreserved.

Keywords:

Bacterialovergrowth;

Breathtest;

Hydrogen;

Methane;

Smallintestine

Peerreviewers:

AntonioGasbarrini,MD,Professor,DepartmentofInternalMedicine,GemelliHospital,CatholicUniversityofRome,LargoA.Gemelli8,00168Rome,Italy;

AnthonyPMoran,BSc,PhD,DSc,FRSC,MRIA,Professor,DepartmentofMicrobiology,NationalUniversityofIrelandGalway,UniversityRoad,Galway,Ireland

BuresJ,CyranyJ,KohoutovaD,Fö

rstlM,RejchrtS,KvetinaJ,VorisekV,KopacovaM.Smallintestinalbacterialovergrowthsyndrome.WorldJGastroenterol2010;

16（24）:

2978-2990Availablefrom:

URL:

DOI:

http:

//dx.doi.org/10.3748/wjg.v16.i24.2978

INTRODUCTION

Humanintestinalmicrobiotacreateacomplexpolymicrobialecology.Thisischaracterisedbyitshighpopulationdensity,widediversityandcomplexityofinteraction.Theduodenumandproximaljejunumnormallycontainsmallnumbersofbacteria,usuallylactobacilliandenterococci,gram-positiveaerobesorfacultativeanaerobes（<

104organismspermL）.Coliformsmaybetransientlypresent（<

103bacteriapermL）andanaerobicBacteroidesarenotfoundinthejejunuminhealthypeople.Uptoonethirdofjejunalaspiratesmightbesterileinhealthyvolunteers.Thedistalileumisatransitionzonebetweensparsepopulationsofaerobicbacteriaoftheproximalsmallintestineandverydensepopulationsofanaerobicmicro-organismsinthelargebowel[1-3].Theepithelialsurfaceofthesmallintestineinahealthyhumanisnotcolonised.Occasionalgroupsofbacteriacanbefoundinlowconcentrationswithinthelumen.Bacteriadonotformclustersandspatialstructures,andtheluminalcontentsareseparatedfromthemucosabyamucuslayer[4].

Anydysbalanceofthiscomplexintestinalmicrobiome,bothqualitativeandquantitative,mighthaveserioushealthconsequencesforamacro-organism,includingsmallintestinalbacterialovergrowthsyndrome（SIBO）.

definition

SIBOisaveryheterogeneoussyndromecharacterisedbyanincreasednumberand/orabnormaltypeofbacteriainthesmallbowel.MostauthorsconsiderdiagnosticofSIBOtobethefindingof≥105bacteria[i.e.colony-formingunits（CFU）]permLofproximaljejunalaspiration.Thenormalvalueis≤104CFU/mL[3,5-7].

prevalence

TheoverallprevalenceofSIBOinthegeneralpublicisunknown.Ingeneral,SIBOissubstantiallyunderdiagnosed.Thereareseveralreasonsforthisfact.SomepatientsmaynotseekhealthcareorSIBOmaynotbeproperlydiagnosedbymedicalinvestigations.SIBOmightbeasymptomaticorwithnon-specificsymptomsonly,andlastbutnotleast,allsymptomsmightbeincorrectlyascribedtotheunderlyingdisease（leadingtoSIBO）.Ofcourse,diagnosticyieldalsodependsonthemethodsusedforinvestigation.Accordingtodifferentstudieswiththeinvestigationofsmallsetsofclinicallyhealthypeopleasacontrol,findingsconsistentwithSIBOwerefoundin2.5%to22%[8-17].

Inparticulardiseasesanddisorders,literaturedataonprevalencediffersubstantially.Forinstance,theprevalenceofSIBOinpatientsfulfillingdiagnosticcriteriaforirritablebowelsyndromewas30%-85%[9-11,16,18,19].TheprevalenceofSIBOincoeliacdiseasenon-respondingtoagluten-freedietwasupto50%[20].Inlivercirrhosis,SIBOwasdiagnosedinmorethan50%ofcases[21,22].Inasmallgroupofelderlypeople（70to94yearsold）withlactosemalabsorption,SIBOwasdocumentedin90%[23].AninterestingstudywasperformedonasymptomaticmorbidlyobesesubjectsandSIBOwasfoundin17%（comparedto2.5%innon-obesepersons）[15].

aetiology

Thereareseveralendogenousdefencemechanismsforpreventingbacterialovergrowth:

gastricacidsecretion,intestinalmotility,intactileo-caecalvalve,immunoglobulinswithinintestinalsecretionandbacteriostaticpropertiesofpancreaticandbiliarysecretion[24].

TheaetiologyofSIBOisusuallycomplex,associatedwithdisordersofprotectiveantibacterialmechanisms（e.g.achlorhydria,pancreaticexocrineinsufficiency,immunodeficiencysyndromes）,anatomicalabnormalities（e.g.smallintestinalobstruction,diverticula,fistulae,surgicalblindloop,previousileo-caecalresections）and/ormotilitydisorders（e.g.scleroderma,autonomicneuropathyindiabetesmellitus,post-radiationenteropathy,smallintestinalpseudo-obstruction）.Insomepatientsmorethanonefactormaybeinvolved.“Aetiological”and“predisposing”factorscannotbeseparatedinsomepatients.SIBOmayoccurinelderlypeoplewithoutanyevidentunderlyingsmallintestinalpathology.

Insomecases,aviciouscirclearises:

anunderlyingdiseaseiscomplicatedbySIBOandthenSIBOdirectly（asamorphologicalimpact）orvicariously（bymalabsorptionornutrientdeficiency）causesfurtherdeteriorationoftheunderlyingdisease.

OutofalldiseasesanddisordersassociatedwithSIBO（listedbelowindetail）,90%ofcasescomprisesmallintestinalmotilitydisorders（ofvariousaetiology）andchronicpancreatitis[2].

Achlorhydria

Achlorhydria（duetochronicatrophicgastritis）andlong-termadministrationofprotonpumpinhibitorsmaycausebacterialovergrowthinthestomachandduodenum.Protonpumpinhibitorsnotonlyincreaseduodenalbacterialcolonisationbutalsoaccelerateintestinaltransit[24].

Exocrinepancreaticinsufficiency

ChronicpancreatitisiscomplicatedbySIBOin30%-40%ofcases[7,25].Multiplefactorscanbeinvolved:

exocrinepancreaticinsufficiency（withabsenceofanti-bacterialeffectofproteolyticenzymes）,abnormalchymeinthesmallintestinallumen,motilitydisorders,administrationofpainkillersandongoingalcoholconsumptioninsomeofpatients.CysticfibrosisisalsoassociatedwithincreasedriskofSIBO.Fridgeetal[26]diagnosedSIBOin14/25（56%）patientswithcysticfibrosis.SIBOmaybeacausativefactorofdiarrhoeainadvancedpancreaticcancer[27]apartfrompancreaticexocrineinsufficiency,chemotherapyorprevioussurgery.

Immunodeficiencysyndromes

Variousimmunodeficiencysyndromes,suchasIgAdeficiency,commonvariableimmunodeficiency,AIDSandothers,arecomplicatedbymiscellaneousinfect