Clinical predictors of small intestinal bacterial overgrowth by duodenal

LetterstotheEditors

A.Gasbarrini,E.Scarpellini,

M.Gabrielli,A.Tortora,F.Purchiaroni&V.Ojetti

DepartmentofInternalMedicine,CatholicUniversityofSacredHeart,GemelliUniversityHospital,Rome,

Italy.

E-mail:agasbarrini@rm.unicatt.itdoi:10.1111/j.1365-2036.2011.04657.x

Clinicalpredictorsofsmallintestinalbacterialovergrowthbyduodenalaspirateculture

SIRS,WereadthepaperbyChoungetal.onclinicalpredictorsassociatedwithsmallbowelbacterialovergrowth(SIBO)diagnosisaccordingtoabnormalduode-nalaspirateculturewithgreatinterest.1Resultsfromthisstudypartlyconfirmdatafromliteratureabouttheassocia-tionbetweenSIBOandelderly,2druguse,2inflammatoryboweldiseases(IBD),3smallboweldiverticulae4andpancreatitis.5InterestinglySIBOwasnotsignificantlyassociatedwithirritablebowelsyndrome(IBS)orprotonpumpinhibitor(PPI)use.

Thestudydesign,retrospectiveandmonocentric,andtheinvestigatedpopula-tionmayexplainsomeoftheseunexpectedfindings.First,theuseofnonconsecu-tivepatientsreferredforsuchdifferentGIdiagnosesclearlyaffectthesampleuniformity.Second,thesmallgroupofIBSpatients,andanabsenceofaconsis-tentIBS-C(constipatedIBS)cohort,referredforduodenalaspirateculturemayexplainthelackofassociationwithSIBO.6Third,thehighmeanageofthepartic-ipantsclearlyfavoursastrongassociationwithelderly,diverticulaeandnarcoticuse.Inaddition,thearticlepointsoutsomelimitationsofduodenalaspiratecul-ture:7aninvasive,expensivetechniquetoassessSIBO,althoughstillconsideredthegold-standard,thatevaluatestheupperduodenaltractovergrowthonly.Somepatientsshowedan‘indeterminate’testresultthatmayincludelesssymptomaticgroup,especiallythoseusingPPI,initiallynotassociatedwithSIBO.8Itisconceiv-ablethat‘indeterminate’testsdescribelowerovergrowthlocalisation,anentityalreadysuggestedbysomeauthorstobeassociatedwithIBS.9ThisarticleconfirmsanassociationbetweenSIBOandsomecommongastro-intestinaldiseases,butmoreinterestinglydrawsnewattentiontotherealimpactofSIBOonIBS,asdetectedbydirectmethods,aseventhegold-standardshowstechni-calissuesthatmaypotentiallybiasaccuracyandinterpretationincomparisonwithbothlesssensitiveindirecttests(breathtests)andthosestudyingmicrobialgenomicsandmetabolomics.

ACKNOWLEDGEMENT

Declarationofpersonalinterests:None.Declarationoffundinginterests:ThisstudywasfundedbyagrantfromFondazioneRicercainMedicina.

AP&Tcorrespondencecolumnsarerestrictedtolettersdiscussingpapersthathavebeenpublishedinthejournal.Alettermusthaveamaximumof300words,maycontainonetableorfigure,andshouldhavenomorethan10references.ItshouldbesubmittedelectronicallytotheEditorsviahttp://mc.manuscriptcentral.com/apt.

1378ª2011BlackwellPublishingLtd

LetterstotheEditors

REFERENCES

1.ChoungRS,RuffKC,MalhotraA,etal.Clinicalpredictorsofsmallintestinalbac-terialovergrowthbyduodenalaspirateculture.AlimentPharmacolTher2011;33:1059–67.

2.ElphickDA,ChewTS,HighamSE,BirdN,AhmadA,SandersDS.Smallbowelbacterialovergrowthinsymptomaticolderpeople:canitbediagnosedearlier?Gerontology2005;51:396–401.

3.PimentelM,MayerAG,ParkS,ChowEJ,HasanA,KongY.Methaneproductionduringlactulosebreathtestisassociatedwithgastrointestinaldiseasepresentation.DigDisSci2003;48:86–92.

4.BjorneklettA,FausaO,MidtvedtT.Bacte-rialovergrowthinjejunalandilealdisease.ScandJGastroenterol1983;18:289–98.5.TrespiE,FerrieriA.Intestinalbacterialovergrowthduringchronicpancreatitis.CurrMedResOpin1999;15:47–52.

6.HaboubiNY,CowleyPA,LeeGS.Smallbowelbacterialovergrowth:acauseofmalnutritionintheelderly?EurJClinNutr1988;42:999–1005.

7.CorazzaGR,MenozziMG,StrocchiA,etal.Thediagnosisofsmallbowel

bacterialovergrowth.Reliabilityofjejunalcultureandinadequacyofbreathhydro-gentesting.Gastroenterology1990;98:302–9.

8.SpiegelBM,CheyWD,ChangL.Bacterialovergrowthandirritablebowelsyndrome:unifyinghypothesisoraspurious

consequenceofprotonpumpinhibitors?AmJGastroenterol2008;103:2972–6.

9.KhoshiniR,DaiSC,LezcanoS,PimentelM.Asystematicreviewofdiagnostictestsforsmallintestinalbacterialovergrowth.DigDisSci2008;53:1443–54.

Y.A.Saito,R.S.Choung,A.R.Zinsmeister&N.J.Talley

DivisionofGastroenterologyandHepatology,MayoClinic,Rochester,

MN,USA.

E-mail:saito.yuri@mayo.edudoi:10.1111/j.1365-2036.2011.04669.x

Clinicalpredictorsofsmallintestinalbacterialovergrowthbyduodenalaspirateculture:authors’reply

SIRS,WeappreciateDrGasbarriniandcolleagues’interestinourpaperreportingtheclinicalfeaturesidentifiedtobeassociatedwithsmallintestinalbacterialovergrowth(SIBO)asdeterminedbyquantitativeduodenalaspirateculture.1,2OurprimarygoalwasnottofocusonIBS.AstudyfocusedonIBSwoulddrawstratified[accordingtoageandperhapsprotonpumpinhibitor(PPI)use]randomsamplesofpatientswithadiagnosisofIBSandappropriatenon-IBSpatients,andeachsubjectwouldthenundergoaduodenalaspirateculturestudy.

Nonetheless,weacknowledgethatwewerequiteinterested–asothersclearlyare–inexploringthepossibleassociationofIBSwithSIBO.Specifically,weiden-tifiedanegativeassociationbetweenIBSandculture-provenSIBO(adjustedforageandgender),andamodestlyincreasedriskforSIBOinthoseusingPPIs.However,wedidobservethatanIBSdiagnosiswasassociatedwithalowerquan-tityofbacteriaintheaspiratecultures,butthatthisassociationwasattenuatedafteradjustingforPPIuse.

DrGasbarrinietal.questionwhetherourretrospectivepatientsamplemayhaveaffectedourfindings.Theyspecificallywonderiftheolderage(overall:mean53years,IBSpatients:49years)andthepaucityofconstipatedpatientsmayhavecontributedtoournotdetectinganassociationbetweenSIBOandIBSorPPIuse.Thesearegoodquestions.TherelationshipbetweenIBS,PPIuseandSIBOinayoungerpatientpopulationremainslessclear,althoughthequantitativeculturestudyofIBSpatientsvs.controlsbyPosserudetal.3inayoungerpatientgroup(meanage:38years)suggestsotherwise.AsSIBOhasbeenlinkedtodiarrhoea,wedonotthinkthattheadditionofconstipatedpatientswouldhavechangedourfindings,butbecauseSIBOhasbeenreportedinpatientswithconstipation-pre-dominantIBS(withalowerfrequency)4andmethane-producingbacteriacandecreaseintestinaltransit,5,6perhapsthisisanareathatneedsgreaterstudy.

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AlimentPharmacolTher2011;33:1378–1385ª2011BlackwellPublishingLtd