Adescriptionofthestudy,andwhyitmatters,bytheauthors‐

ThespreadofantibioticresistantbacteriaintheHudson:onemorereasontocareaboutreducingsewagepollutioninourwaterways

BySuzanneYoung1,AndyJuhl2,andGregO’Mullan1,21SchoolofEarthandEnvironmentalSciences,QueensCollege,CUNY2LamontDohertyEarthObservatoryofColumbiaUniversity

ThewaterwaysofNewYorkCityareavaluablenaturalandrecreationalresource(Figure1)andtheirhealthdependsonresponsiblestewardship.WhileconditionshaveimprovedgreatlyintheHudsonRiverandNewYorkHarboroverthelast30years,thereleaseofsewageintoourwaterways

continuestothreatenecosystemhealthandoptimalwaterquality.Perhapstheproblemthatpresentsthemostimmediateheaththreattothosewhocontactriverwateristhebillionsofgallonsofcombinedstormwater,mixedwithrawhumansewage,thatareexpelledintotheHudsonRivereachyear.This

happenswhenrainwaterentersoursewersystemviastormdrainsandmixeswithsanitarysewage.Thecombinedvolumecanoverwhelmthecapacityofthepipesleadingtoourwastewatertreatmentplants.Toavoidsewerbackups,aportionofthiscombinedstormwaterandsewageissometimesdivertedinto

ourwaterwaysbeforeithasbeenprocessedinatreatmentplanttoremovebacteriaandothercontaminants.Thisprocessofreleasingstormwatermixedwithsewageisreferredtoasa“combinedseweroverflow”(CSO).Whileweknowthatuntreatedsewagecancontaindisease‐causingorganisms,

wedon’talwaysknowwhatkindsofpotentiallydangerousorganismsareactuallypresent.Arecentstudybyourlaboratorygroup,publishedin2013,confirmedthattheabundanceofantibioticresistantbacteriainHudsonRiverEstuary(HRE)waterisconnectedtosewagepollutionandfoundthatlevels

oftheseresistantbacteriaintheHREincreasedfollowingrainfall,presumablyduetoCSOcontamination(Figure2).Inaddition,manyoftheresistantbacteriadetectedinHREwater,especiallyfollowingrainfall,weresimilartobacteriafoundinthehumanintestineandinsomecasesweresimilar

togroupsofbacteriathathavebeenassociatedwithantibioticresistantinfections.Samplesforthisstudywerecollectedinparallelwiththemonthlywaterqualitymonitoring

programconductedbyRiverkeeper,incollaborationwithQueensCollegeandtheLamontDohertyEarth

ObservatoryofColumbiaUniversity(Figure3and4).TheRiverkeepersamplingprogramdeterminesthelevelofEnterococci,commonlymeasuredsewage‐indicatingbacteria,atseventy‐fiveHudsonRiverlocationsspanningtheentiretidalportionoftheHRE(www.riverkeeper.org/water‐quality).Our

recentlypublishedstudydemonstratesaclearconnection(correlation)betweenthelevelofEnterococciandthelevelofantibioticresistantbacteriainHREwatersamples(Figure2).Thisisasignificantfindingsinceitdemonstratesthatthecommonlymeasuredsewageindicator,Enterococcus,alsorepresentsthe

abundanceofothermicrobesofconcern,suchasantibioticresistantbacteria.ThisprovidesadditionalsupportfortheuseofEnterococciasavaluableindicatorinwaterqualitymonitoringprograms.

Antibioticresistantinfectionsaregrowingasapublichealthcrisis,withnew“superbugs”

emergingandeffectivetreatmentsofteneludingphysicians.Thespreadandtransmissionofresistant

bacteriathroughenvironmentalpathwaysisanimportantcomponentofunderstandingtheproblemandtakingstepstowardsimplementingpreventativemeasurestoprotectthepublic.Polluted

waterwayscontainresistantbacteria,withgreaterlevelsofsewagepollutionresultinginmoreresistantbacteriainourwaterwaysandperhapsgreatersusceptibilityforinfectionofthepublic.

Morethoroughepidemiologicalstudyisnecessaryinordertoquantifyandfullyassesstherisk

thatthisissueposestothepublic.However,thisrecentstudyillustratesonemorereasontocareaboutHudsonRiverwaterqualityandtoreducesewagepollutionviaimprovedmanagementandupgradestowastewaterinfrastructureinourcommunities.Thisstudywasthefirsttodirectlymeasure

antibioticresistantbacteriaintheurbanHudsonRiverEstuaryandwasthefirststudytodemonstrateaclearconnectionofthenumberofsewageindicatingbacteriawiththelevelsofantibioticresistantbacteriainanestuary.

Youcanlearnmoreabouttheresearchdescribedabovebyreadingthefullscientificpaper:“Antibiotic‐resistantbacteriaintheHudsonRiverEstuarylinkedtowetweathersewagecontamination”2013.JournalofWaterandHealth,Volume11,Number2,pages297‐310.Doi:10.2166/wh.2013.131

Ifyouhavequestionsaboutthestudyyoushouldcontactthecorrespondingauthorforthestudy:Dr.GregoryO’MullanfromQueensCollege;718‐997‐3452;gomullan@qc.cuny.edu

Figure1:KayakersenjoyingtheHudsonRiver,withManhattaninthebackground,onawarmsummerday.

Figure2:Illustrationofcombinedseweroverflow(CSO)inNewYorkCityandtheconnectionbetweenlevelsofsewageindicatingbacteria(Enterococci;browndots)andAntibioticResistantBacteria(ARB;pinkdots).PanelA‐Duringdry,sunnyweathersewageisdeliveredfromthecitytowastewatertreatmentplants,andtreatedeffluent(bluearrow)isreleasedintotheestuary.PanelB‐Rainwaterfromstreetdrainscombinewithsanitarysewageandoverwhelmsthecapacityofpipesdeliveringsewagetotreatmentplants,causingCSOtoreleaseuntreatedsewageintotheestuary(brownarrow)fromapproximately500locationsinNewYorkHarbor.CSOdischargecontainsbothEnterococciandARB.Thelevelsofthesebacteriaarecorrelated,demonstratingthatEnterococciisaveryusefulindicatorofothermicrobesofconcernincludingantibioticresistantbacteria.PanelC‐InthehoursanddaysimmediatelyfollowingrainfallandCSOdischarge,thelevelsofbothEnterococciandARBareelevated,oftenhundredstothousandsoftimeshigherthanduringdryweather.PanelD‐AfterseveraldaysofdryweatherthelevelsofEnterococciandARBdecreasetobackgroundlevels.

Figure3:Fieldsampling.PanelA‐ReddotsidentifysamplingsitesaroundNewYorkCityandtheTappanZeeusedinthestudy.PanelB‐NewYorkCityDepartmentofEnvironmentalProtectionmapwithdotsshowingthelocationofmorethan400CSOsinNewYorkHarbor.PanelC‐TheRiverkeeperpatrolboat,usedtocollectsamplesforthisstudy.PanelD‐PublicdockinFlushingBayusedforhighfrequencysamplinginthisstudy.

Figure4:Collectionandlabprocessingofsamples.PanelA‐WatersampleswerecollectedfromtheHudsonRiverEstuaryinsterilebottlesandtransportedtothelaboratoryatQueensCollegeforprocessing.PanelB‐Inthelaboratorywaterwasspreadontomediaplates,withandwithoutantibiotics,togrowbacteriacollectedfromtheestuarywater.PanelsCandD‐Mediaplateswereincubatedinthelaboratoryandthenthenumberofbacteriathatgrewwerecounted.Mediaplateswithoutantibiotics(PanelC)hadfarmoregrowththanplateswithantibioticsadded(PanelD)butantibioticbacteriaweredetectedateverysamplingsitetestedandincreasedafterrainfall.