1
Results Introduc.on Methods Conclusions If E. coli are naturalized to the soil environment in Bangladesh, their presence may contribute to on going transmission of pathogenic E. coli. Our work in Tanzania demonstrated the presence of virulence genes for five common diarrheagenic E. coli in soils. Though it is likely that the virulence genes detected in Tanzania were carried by enteric E. coli, it is also possible that the genes were detected in other microbiota, and/or that the genes were passed from enteric and environmental strains through horizontal gene transfer. Gene transfer between soil microbiota is a well-recognized phenomena, as is gene transfer of E. coli virulence genes. If horizontal gene transfer is possible between environmental E. coli, enteric E. coli, and/or other microbiota, then environmental E. coli pose a risk of becoming pathogenic if enteric E. coli are introduced. Evidence of the exchange of geneLc material between environmental and enteric E. coli in the soil environment would dramaLcally impact the current paradigm concerning environmentally-mediated enteric disease transmission by suggesLng that the environment can amplify disease transmission. Acknowledgements Dr. Lee Riley Dr. Aminul Islam Clarissa Arujo Growth Kine.cs of E. Coli Isolates from Domes.c Environments Authors: Sayah Bogor, Dr. Aminul Islam ICDDR’B and University of California Berkeley, Department of InfecLous Diseases and Vaccinology Dhaka, Bangladesh Diarrheagenic E. coli and Shigella spp. are responsible for a substanLal burden of diarrheal disease in Bangladesh. In Mirzapur, for example, the two are amongst the eLological agents most responsible for diarrhea in children. The ExisLng paradigm for enteric disease transmission is that the environment acts as a reservoir. There is limited to no emphasis on the potenLal role of the environment to amplify enteric diseases. In this study, we invesLgated whether or not the soil reservoir can aid amplificaLon of diarrheagenic E. coli. Relevance: If soil can act to amplify diarrheagenic E. coli, then efforts to reduce diarrheal disease need to place greater emphasis on environmental hygiene in combinaLon with exisLng emphasis on water and sanitaLon infrastructure provision Hypotheses: 1. Households pracLcing domesLc animal husbandry contain more, and different, strains of E. coli than households without domesLc animals. 2. E. coli in the soil are phenotypically and geneLcally disLnct from enteric E. coli in human and animal feces. 3. E. coli in the soil are capable of persisLng and growing in the soil beYer than enteric E. coli due to adaptaLon to the soil environment. 4. The soil environment contains a gene pool that provides opportuniLes for virulence and/or environmental persistence gene transfer. 1. Collected soil and fecal samples from 52 households (26 with, and 26 without, ruminants). 2. Isolated and assessed phenotypic and genotypic characterisLcs of E. coli in samples 3. Assessed growth rates, and factors influencing growth rates of E. coli in microcosm studies. 4. Developed microcosm condiLons under which E. coli strains (including pathogenic strains) are capable of long term persistence and/or growth 5. Compared microcosm condiLons developed in 4) to observed condiLons in household environments to idenLfy likelihood that pathogenic E. coli thrive in the environment. Fig 1. Per cent populaLon decline of E. coli strains in different tropical soils and cocopeat under controlled condiLon. A—Wetland soil; B—Red lateriLc soil; C—Black coYon soil; D—Tropical latosol; E— Cocopeat. Means of three replicate values ploYed and errors bars indicate the standard error. In 2010, researchers went to Tanzania to invesLgate contaminaLon of women’s hands. It was demonstrated that women’s hands were contaminated with an average 3.5 log 10 CFU E. coli per two hands, respecLvely. Furthermore, we found that household acLviLes (e.g., sweeping, preparing food, cleaning dishes) readily and rapidly contaminate hands with E. coli only a few minutes aeer hand washing. These findings indicate that the source of fecal bacteria is likely the environmental reservoirs commonly found throughout the home, including household utensils, market produce, floors, and surfaces. Follow up study found substanLally higher concentraLons of E. coli on household items (e.g., cups, plates, wash basins, toys, brooms) than are typically observed in industrialized regions like the United States and European Union. Similarly, soil samples from the household plot contained on average 2.1 log 10 E. coli per gram. InteresLngly, E. coli and enterococci concentraLons measured in soils collected from inside the home, (including the locaLon where food is prepared) were higher than concentraLons in soils from inside or near the latrine. References 1. Kotloff KL, Nataro JP, Blackwelder WC, Nasrin D, Farag TH, et al. (2013) Burden and aeLology of diarrhoeal disease in infants and young children in developing countries (the Global Enteric MulLcenter Study, GEMS): a prospecLve, case-control study. Lancet 382: 209-222. 2. Wagner EG, Lanoix JN (1958) Excreta disposal for rural areas and small communiLes. Excreta Disposal for Rural Areas and Small CommuniLes. 3. Levy K, Nelson KL, Hubbard A, Eisenberg JNS (2008) Following the water: a controlled study of drinking water storage in northern coastal Ecuador. Environmental Health PerspecLves 116: 1533. 4. hYp://journals.plos.org/plosone/arLcle?id=10.1371%2Fjournal.pone.0130038 Special Thanks to the Subir and Malini Chowdhury Center for Bangladesh Studies

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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