LABORATORY EXERCISE BACTERIA & HAND WASHING

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1 LABORATORYEXERCISE BACTERIA&HANDWASHING101 Purpose/Objectives: Todeterminewherebacteriaexistinourenvironment Totesthowtime,method,amountofsoap,orwatertemperatureaffecttheefficiencyof handwashing Totesttheanti microbialeffectofdifferenthandcleansingproductsand natural antibacterialagents. Backgroundinformation: Bacteriaareadiversegroupofmicroscopic,single celledorganisms.virusesaremicroscopic andinfectcellsusingthecellsashostsforreproduction.bothbacteriaandvirusescancausedisease inhumans.however,bacteriaandvirusesexistintheenvironmentallaroundusandmostdonot harmpeople. Apandemicisanoutbreakofadiseasearoundtheworld.Scientistsandhealthprofessionals areconcernedaboutthepossibilityofanh1n1influenza(flu)pandemic.whenaflupandemic happens,peoplemayhavelittleornoimmunity,andavaccinemaynotexistforthisnewfluvirus. Thediseasethenspreadseasilyperson to personandmaycauseseriousillnessacrossthecountry andaroundtheworldveryquickly.avaccineiscurrentlybeingtestedfortheh1n1influenza. AccordingtotheCentersforDiseaseControlandPrevention,themostcommonmethod thatpathogensarespreadisviathehands.therefore,properhandhygienehelpstolimitthespread ofthefluandotherinfectiousdiseases,andisthesinglemosteffectivewaytopreventthespreadof disease.handwashingreducesdiseasesthatarespreadthroughfecal oralorhand to mouth transmission,directorindirecttransmission(i.e.,closecontactbysharingpersonalitems),and respiratoryorairbornetransmission(i.e.,coughingorsneezing). Therearemanyhandcleansingproductsonthemarket.About75percentofliquidsoaps currentlyonshelvesinamericangrocerystoresdisplaytheword antibacterial ontheirlabels,and weareconstantlyaddingnewantibacterialproductstoourcleansingarsenals.theuseof antibacterialchemicalsiscontroversial(see Do Antibacterial Soaps do More Harm Than Good? from ScientificAmerican,February2008). Inthisactivity(partiallyadoptedfromtheNationalInstituteofEnvironmentalHealth Sciences),youwill testwherebacteriaexistintheenvironment.(itisimportanttonotethatinfluenzais causedbyavirus,notabacterium.) testahypothesisaboutthemosteffectivehand washingmethod. testahypothesisaboutthemosteffectivehand cleansingproduct. 1

2 PARTI INVESTIGATINGBACTERIAINTHEENVIRONMENT Materials: 1agarplatepergroupPLUS1agarplateperindividual sterilecottonswabs(6perplate) sterilewater 1marker 1ruler Parafilm(tosealagarplate) Procedure 1. Drawlinesonthebottomofthegroup sagarplate(thesidewiththeagaronit)tomark6equal sizedregions(similartoslicingapie). 2. Asagroup,decidewhat6environmentsyouwillinvestigate.Itmightbesomeenvironmentinthe roomorsomewhereinthesciencebuilding.youcanalsocomparetheenvironmentbeforeand aftertreatment(forexamplethedeskbeforeandafteryoucleanitwithsanisol). 3. Labeleachregionoftheplatewiththeenvironmentyouwillbetesting. 4. Carryasterilecottonswabandagarplatetotheenvironment,andusetheswabtocollectthe samples.ifyouarecollectingfromadrysurface,youshouldfirstdipthecottonswabinsterile waterandthenswabthesurface. 5. Opentheagarplateandlightlystreaktheswabbackandforthacrosstheagarinthe appropriatelylabeledregion.discardtheswabinthereceptacleprovided. 6. SealthedishwithParafilmandwaituntilyouhaveallthegroups platesfromallportionsofthe laboratory.theinstructorwillincubatetheplatesat37ºcovernight.thenextlaboratoryperiod youwillobservetheresultsandrecorddata. 7. Repeatthisprocedureathomewithatleastoneenvironmentonyourindividualplateonyour owntimethisevening.bringplatetoclassnextmeeting PARTII TESTING NATURAL ANTIBACTERIALAGENTS\ Materials: 1agarplatepergroup 1sterilecottonswab 1bacteriaculture(sharedwithclass) filterpapersoakedinlemonjuice,teetreeoil,vinegar,grapefruitseedextractoil filterpaperavailabletosoakinitemsbroughtinbystudents Procedure 1. Drawlinesonthebottomofthegroup sagarplate(thesidewiththeagaronit)tomark6 equalsizedregions(similartoslicingapie). 2. Labeleachofthe6regionswiththe natural antibacterialagentthatwillbetested. 3. Dipthesterilecottonswabintothebacteriacultureandgentlyspreadbacteriaalloverthe agarplate.trytocompletelycovertheplate. 4. Placeapieceoffilterpapersoakedintheantibacterialagentsonthecorrectlylabeledregion oftheplate. 5. SealthedishwithParafilmandwaituntilyouhaveallthegroups platesfromallportionsof thelaboratory.theinstructorwillincubatetheplatesat37ºcovernight.thenextlaboratory periodyouwillobservetheresultsandrecorddata. 2

3 PartIII:Investigatinghandwashingmethods Thissectioninvolvesdesigningyourownexperiment.Readtheinformationandremembertouse scientificmethodtothinkabouthowtoansweraspecificquestion. Materials: Glogel(sharedwiththeclass) Handwashingsoap&papertowels Stopwatches(sharedwithyourgroup) UVlights(sharedwiththeclass) optional fingernailbrush,scrubsoap General Information & Guidelines for Glo Gel experiment: 1. Youwillconductanexperimenttodeterminethebestmethodtowashhands. 2. Glo Gel willbeusedtosimulate germs.notethattheglogelisnotactuallygerms,itjust SIMULATESgerms.Thiswayyoucanobservebeforeandafterwithouthavingtogrowthe bacteriaovernight.tousetheglo Gel,applyasmallamountasifthegelwerehandlotion, makingsuretospreadthegelcompletelyonhands(i.e.,frontandback,betweenfingers). 3. AUVlightwillilluminatethe germs totesttheeffectivenessofthehandwashingmethod.itis importanttonotlookattheuvlightdirectlyasitcancausedamagetotheeyes.theuv lightisusedonlytoobservetheeffectivenessofhandwashing. 4. Divideintogroupsofatleastfivestudentspergroup.Possiblegroupmemberroles:atleastone recorderandtimer,andthreetofourhandwashers.notethatthecontrolwillbetousethehand gelbutnotwash,sincewashingiswhatisbeingtested. 5. Somepossibleindependentvariablesarelengthoftimespentwashing,temperatureofthewater, methodforscrubbing,ornumberofpumpsofsoap.typeofsoapwouldnotbeusedasavariable forthissegmentoftheinvestigationastheglo Gel doesnotdistinguishbetweenvarioussoapsor cleaners/disinfectants(i.e.,handsanitizerversusantibacterialsoapordishsoap).yourgroup shouldonlychooseonevariablethatchanges.makeyourlife easy. 6.Hereassomesamplequestionstoinvestigate: Howdoeslengthoftimeeffecthandwashingeffectiveness(0,10,20,or30seconds)? Howdoestemperatureofwatereffecthand washingeffectiveness(cold,lukewarm,orhot)? Howdoesmethodforscrubbingaffecthand washingeffectiveness(useoffingernail brush,rubbinghard,etc.)? Howdoesthenumberofpumpsofsoapeffecthand washingeffectiveness(0,1,2,3)? 7. Inyourexperiment,youwillchangetheindependentvariable(time,temperature,method,or pumps)whileotherfactorswillnotchange.forexampleifiweredesigninganexperimenttotest howthenumberofpumpsofsoapeffectshand washing,theniwouldtest1pump,2pumps,and 3pumpsastheindependentvariables.Foreachofthosetrials,Iwillkeepthetime,temperature, andmethodconstant.thedependentvariableishandcleanliness.youaretestinghowthe dependentvariablechangesatdifferentlevelsoftheindependentvariable. 8. BEFOREbeginningtheexperiment,developahypothesisandcompletethatportionofthe Assignment.Defineyourdependentandindependentvariables. 9. Designyourexperiment.Seekouttheinstructorforassistanceandapprovalbeforestartingto executetheexperiment. 3

4 10. Tohelpwiththedatacollection,completetheHandprintFiguresasyourdatarecordingto estimatethepercentageofthehandsthatwerecleanedastheindependentvariablechanged. TherecordercancolororshadeinboxesshowingwherethehandsarestillDIRTY(theseareaswill illuminateundertheuvlight).remembertolookatbothsidesofthehandsandthenestimate thepercentageofthehandsthatwerecleanedbycountingthenumberof clean boxes. Toestimatethepercentageofthehandsthatwascleaned: 1.Countthetotalnumberof clean boxes,tothenearestquarterofabox,foreachside(top andbottom)ofeachhand 2.Thendividethatnumberby308,thetotalnumberofboxes.Donotcountboxesthatare lessthanhalfthesizeofaregularbox. Thewholegroupwillturninonedatasetofhandfigures.Besuretoincludeeveryone s namesonthedatasheets.providealltheinformationrequestedandgivedetailedexplanationsfor eachsectionoftheassignment.thisisparticularlyimportantfortheprotocolandresults/conclusion sections. PartIV:Comparisonofhandcleansingproducts Materials (per group) 2 3agarplates(1/2ofaplateperperson) sterilecottonswabs(2foreachperson) sterilewater 1marker Parafilm(tosealallagarplates) Handcleansingproducts(dishsoap,Purell,antibacterialsoap(withTriclosan)) Procedure 1. Drawlinesonthebottomofthegroup sagarplates(thesidewiththeagaronit)tomark4equal sizedregions(similartoslicingapie). 2. Eachgroupmemberwillchooseonetypeofsoaptotest(trytohaveavarietyofsoapsamongst yourgroup).twoofthe4regionswillcorrespondtoonetypeofsoap.onesectionrepresenting before andtheothersectionrepresenting after. 3. Tomakeeveryone shands dirty eachpersonshouldhandle(hold,touch,jingle,count)10 penniesorsomethingdirtyfor1minute 4. Forthesectionlabeled before takeasterilecottonswabanddipitintosterilewater.rubthe wetcottonswaboverthewholeindexfingerandpalmofthelefthand.thenopentheagarplate andlightlystreaktheswabbackandforthacrosstheagaronthe before side.discardtheswab inthereceptacleprovided. 5. Forthesectionlabeled after,washorcleansehandsusingthechosenproduct.(ifitissoap,take onepumpandwashinwarmwaterfor20secondsanddrywithpapertowels.ifitisantibacterial gel,takeonedime sizedsquirtandrubuntildry).aftercleansing,takeasterilecottonswaband dipitintosterilewater.rubthewetcottonswaboverthewholeindexfingerandpalmoftheleft hand.thenopentheagarplateandlightlystreaktheswabbackandforthacrosstheagaronthe after side.discardtheswabinthereceptacleprovided. 6. Aftereachplateisfinished,sealthedishwithParafilm,placeallyourgroup splatesinastack,and bringthemtotheareaindicatedbytheinstructor.theinstructorwillincubatetheplatesat37ºc overnight.youwillobserveanddescribetheresultsinthenextlaboratoryperiod. 4

5 LABORATORYASSIGNMENT BACTERIA&HANDWASHING101 GroupMembers: PartI InvestigatingBacteriaintheenvironment 1.Whatenvironmentsdidyouinvestigate?Indicateanytreatmentsyouapplied Drawanddescribewhatyourplatelookedlikefollowingincubation: 3.Examineplatesformanothergroupthatinvestigateddifferentenvironments.Recordyour observationsfromthreeofthoseenvironmentsbelow: Environment Observations: Environment Observations: Environment Observations: 5

6 PartII Testing natural antibacterialagents 1.Whatchemicalsdidyouinvestigate? Drawanddescribewhatyourplatelookedlikefollowingincubation: 3.Didanyofthesenaturalproductspreventbacterialgrowth?Whichone(s)workedthebestand why? 4.Whywouldorganisms,suchasplants,haveantibacterialproperties? 6

7 PartIII:Investigatinghandwashingmethods ExperimentTitle:Include a descriptive title of your experiment. IndependentVariable: Control: Level1: Level2: Level3: DependentVariable(s): Question: What are you trying to figure out? Hypothesis: Write your prediction regarding how the independent variable will affect the dependent variable. MaterialsUsed: List the materials used to conduct the experiment. Be specific and include everything (Hint: there should be about 8 items). This list will help you write a detailed experimental protocol as required in the next section. 7

8 Protocol: Identify the steps you took to complete the experiment. Be sure to be clear, concise, and include details so that another group would be able to correctly follow the procedure as you intended. For example, how many pumps of soap were used? Was the water running and then hands placed under the running water at the same time the stopwatch is started? What was the temperature of the water? How were hands dried? 8

9 HandprintFigureData(1perindependentvariable) IndependentVariable: (i.e.30seconds,or1pump) 9

10 Results,Conclusions&Discussion: Explain the results of your experiment and draw any conclusions. Be sure to discuss both quantitative (i.e. percentage of hands cleaned) and qualitative (e.g. the glow gel remained in the nail cuticles) results. Make sure the connections between the dependent and independent variables are explained clearly. Discuss possible errors and how each of those errors may have affected your results. For example, differences in hand washing technique, and other things that may have varied beyond your control. Give suggestions for further study or refinement of the present experimental protocol. 10

11 PartIV Comparisonofhandcleansingproducts 1.Recordwhichcleansingproductsyourgroupused: 2.Drawanddescribewhattheplatesforeachproducelookedlikefollowingincubation: 3.Compareyourresultstootherindividualsorgroups andrecordanyobservationsbelow(were theythesame,didtheygetdifferentresults,etc.) Cleansingproduct Observations: Cleansingproduct Observations: Cleansingproduct Observations: 4.BASEDONTHEDATAANDOBSERVATIONS,whichofthethreehandcleansingproductsismost effectiveandwhy? 5.Whataresomethingsoneshouldconsiderbeforepurchasingorusinganytypeofcleanser(hand, body,kitchen,bathroom,etc.)? 11