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Results

Introduc.on

Methods

ConclusionsIfE.coliarenaturalizedtothesoilenvironmentinBangladesh,theirpresencemaycontributetoongoingtransmissionofpathogenicE.coli.OurworkinTanzaniademonstratedthepresenceofvirulencegenesforfivecommondiarrheagenicE.coliinsoils.ThoughitislikelythatthevirulencegenesdetectedinTanzaniawerecarriedbyentericE.coli,itisalsopossiblethatthegenesweredetectedinothermicrobiota,and/orthatthegeneswerepassedfromentericandenvironmentalstrainsthroughhorizontalgenetransfer.Genetransferbetweensoilmicrobiotaisawell-recognizedphenomena,asisgenetransferofE.colivirulencegenes.IfhorizontalgenetransferispossiblebetweenenvironmentalE.coli,entericE.coli,and/orothermicrobiota,thenenvironmentalE.coliposeariskofbecomingpathogenicifentericE.coliareintroduced.EvidenceoftheexchangeofgeneLcmaterialbetweenenvironmentalandentericE.coliinthesoilenvironmentwoulddramaLcallyimpactthecurrentparadigmconcerningenvironmentally-mediatedentericdiseasetransmissionbysuggesLngthattheenvironmentcanamplifydiseasetransmission.

AcknowledgementsDr.LeeRileyDr.AminulIslamClarissaArujo

GrowthKine.csofE.ColiIsolatesfromDomes.cEnvironmentsAuthors:SayahBogor,Dr.AminulIslam

ICDDR’BandUniversityofCaliforniaBerkeley,DepartmentofInfecLousDiseasesandVaccinologyDhaka,Bangladesh

DiarrheagenicE.coliandShigellaspp.areresponsibleforasubstanLalburdenofdiarrhealdiseaseinBangladesh.InMirzapur,forexample,thetwoareamongsttheeLologicalagentsmostresponsiblefordiarrheainchildren.TheExisLngparadigmforentericdiseasetransmissionisthattheenvironmentactsasareservoir.ThereislimitedtonoemphasisonthepotenLalroleoftheenvironmenttoamplifyentericdiseases.Inthisstudy,weinvesLgatedwhetherornotthesoilreservoircanaidamplificaLonofdiarrheagenicE.coli.Relevance:IfsoilcanacttoamplifydiarrheagenicE.coli,theneffortstoreducediarrhealdiseaseneedtoplacegreateremphasisonenvironmentalhygieneincombinaLonwithexisLngemphasisonwaterandsanitaLoninfrastructureprovisionHypotheses:1.  HouseholdspracLcingdomesLcanimalhusbandrycontainmore,anddifferent,

strainsofE.colithanhouseholdswithoutdomesLcanimals.2.  E.coliinthesoilarephenotypicallyandgeneLcallydisLnctfromentericE.coliin

humanandanimalfeces.3.  E.coliinthesoilarecapableofpersisLngandgrowinginthesoilbeYerthanenteric

E.coliduetoadaptaLontothesoilenvironment.4.  ThesoilenvironmentcontainsagenepoolthatprovidesopportuniLesforvirulence

and/orenvironmentalpersistencegenetransfer.

1.  Collectedsoilandfecalsamplesfrom52households(26with,and26without,ruminants).

2.  IsolatedandassessedphenotypicandgenotypiccharacterisLcsofE.coliinsamples

3.  Assessedgrowthrates,andfactorsinfluencinggrowthratesofE.coliinmicrocosmstudies.

4.  DevelopedmicrocosmcondiLonsunderwhichE.colistrains(includingpathogenicstrains)arecapableoflongtermpersistenceand/orgrowth

5.  ComparedmicrocosmcondiLonsdevelopedin4)toobservedcondiLonsinhouseholdenvironmentstoidenLfylikelihoodthatpathogenicE.colithriveintheenvironment.

Fig1.PercentpopulaLondeclineofE.colistrainsindifferenttropicalsoilsandcocopeatundercontrolledcondiLon.A—Wetlandsoil;B—RedlateriLcsoil;C—BlackcoYonsoil;D—Tropicallatosol;E—Cocopeat.MeansofthreereplicatevaluesploYedanderrorsbarsindicatethestandarderror.

In2010,researcherswenttoTanzaniatoinvesLgatecontaminaLonofwomen’shands.Itwasdemonstratedthatwomen’shandswerecontaminatedwithanaverage3.5log10CFUE.colipertwohands,respecLvely.Furthermore,wefoundthathouseholdacLviLes(e.g.,sweeping,preparingfood,cleaningdishes)readilyandrapidlycontaminatehandswithE.colionlyafewminutesaeerhandwashing.Thesefindingsindicatethatthesourceoffecalbacteriaislikelytheenvironmentalreservoirscommonlyfoundthroughoutthehome,includinghouseholdutensils,marketproduce,floors,andsurfaces.

FollowupstudyfoundsubstanLallyhigherconcentraLonsofE.colionhouseholditems(e.g.,cups,plates,washbasins,toys,brooms)thanaretypicallyobservedinindustrializedregionsliketheUnitedStatesandEuropeanUnion.Similarly,soilsamplesfromthehouseholdplotcontainedonaverage2.1log10E.colipergram.InteresLngly,E.coliandenterococciconcentraLonsmeasuredinsoilscollectedfrominsidethehome,(includingthelocaLonwherefoodisprepared)werehigherthanconcentraLonsinsoilsfrominsideornearthelatrine.

References

1.KotloffKL,NataroJP,BlackwelderWC,NasrinD,FaragTH,etal.(2013)BurdenandaeLologyofdiarrhoealdiseaseininfantsandyoungchildrenindevelopingcountries(theGlobalEntericMulLcenterStudy,GEMS):aprospecLve,case-controlstudy.Lancet382:209-222.2.WagnerEG,LanoixJN(1958)ExcretadisposalforruralareasandsmallcommuniLes.ExcretaDisposalforRuralAreasandSmallCommuniLes.3.LevyK,NelsonKL,HubbardA,EisenbergJNS(2008)Followingthewater:acontrolledstudyofdrinkingwaterstorageinnortherncoastalEcuador.EnvironmentalHealthPerspecLves116:1533.4.hYp://journals.plos.org/plosone/arLcle?id=10.1371%2Fjournal.pone.0130038

SpecialThankstotheSubirandMaliniChowdhuryCenterforBangladeshStudies