Beginning of Microbes - KSUfac.ksu.edu.sa/sites/default/files/lec._2_bacterial... · 2017. 10....

BeginningofMicrobes•  Bacteriafirstappearedon

earthabout3.6billionyearsago,longbeforetheappearanceofHomosapiensaround100,000yearsago..VanLeeuwenhoekwasthefirstpersontovisualize,graphicallyillustrate,andlabel"animalcules"(bacteria)thathefoundinplaquescrapedfromhisownteeth.

Biofilmisacomplexsubstance.

•  AbiofilmisacomplexaggregaEonofmicroorganismsgrowingonasolidsubstrate.Biofilmsarecharacterizedbystructuralheterogeneity,geneEcdiversity,complexcommunityinteracEons,andanextracellularmatrixofpolymericsubstances.

BiofilmsupportstheBacterialgrowth

•  Biofilmareacommonmodeofbacterialgrowthinnatureandtheirpresencehasanenormousimpactonmanyaspectsofourlives,suchassewagetreatment,corrosionofmaterials,foodcontaminaEonduringprocessing,pipecollapse,plant-microorganismsinteracEoninthebiosphere,theformaEonofdentalplaque,thedevelopmentofchronicinfecEonsinliveEssue(masEEs,OEEs,pneumonia,urinaryinfecEons,osteomyeliEs)orproblemsrelatedtomedicalimplants.

BiofilmsincreasesAn:bio:cresitance

WithmicroorganismsarehighlyresistanttoanEmicrobialtreatmentandaretenaciouslyboundtothesurface

TechnologyunderstandsBiofilmsbe>er…

•  Technologicalprogressinmicroscopy,moleculargeneEcsandgenomeanalysishassignificantlyadvancedourunderstandingofthestructuralandmolecularaspectsofbiofilms,especiallyofextensivelystudiedmodelorganismssuchasPseudomonasaeruginosa.

StepsinBiofilmforma:on

Dentalplaque

•  Dentalplaqueisayellowishbiofilmthatbuildupontheteeth.Ifnotremovedregularly,itcanleadtodentalcaries.

Forma:onofDentalBiofilms

•  Throughthegrowthprocessoftheplaquebiofilm,themicrobialcomposiEonchangesfromonethatisprimarilygram-posiEveandstreptococcus-richtoastructurefilledwithgram-negaEveanaerobesinitsmorematurestate.

CDC–onBiofilms

•  Biofilmsformonthesurfaceofcatheterlinesandcontactlenses.Theygrowonpacemakers,heartvalvereplacements,arEficialjointsandothersurgicalimplants.TheCDC(CentersforDiseaseControl)esEmatethatover65%ofNosocomial(hospital-acquired)infecEonsarecausedbybiofilms.

BiofilmsinterfereinAn:bio:cTherapy

•  BacteriagrowinginabiofilmarehighlyresistanttoanEbioEcs,upto1,000Emesmoreresistantthanthesamebacterianotgrowinginabiofilm.Standardan8bio8ctherapyisoTenuselessandtheonlyrecoursemaybetoremovethecontaminatedimplant.

BacteriaassociatedwithBiofilmsdiffer

•  BacterialivinginabiofilmcanhavesignificantlydifferentproperEesfromfree-floaEngbacteria,asthedenseandprotectedenvironmentofthefilmallowsthemtocooperateandinteractinvariousways.OnebenefitofthisenvironmentisincreasedresistancetodetergentsandanEbioEcs,asthedenseextracellularmatrixandtheouterlayerofcellsprotecttheinteriorofthecommunity.

BiofilmsaGreatthreattoImplants

•  AsignificantnumberofpeopleareaffectedbybiofilminfecEonswhichdeveloponmedicaldevicesimplantedinthebodysuchascatheters(tubesusedtoconductfluidsinoroutofthebody),arEficialjoints,andmechanicalheartvalves.Whenimplantedmaterialbecomescolonizedbymicroorganisms,aslowdevelopingbutpersistentinfecEonresults.

BiofilmandAn:bio:cresistance•  Akeypropertyofbiofilms

isthatindividualmicroorganismsareboundtogetherbyapolymericsubstanceThisprotecEveencapsulaEonisbelievedtoplayaroleinsomeanEbioEc-resistantinfecEon.

BiofilmsinCys:cfibrosis

•  Biofilmsareinvolvedinnumerousdiseases.IncysEcfibrosispaEentshavePseudomonasinfecEonsthatoTenresultinanEbioEcresistantbiofilms.

Endocardi:sandBiofilms

•  MicroorganismsmayaYachanddevelopbiofilmsoncomponentsofmechanicalheartvalvesandsurroundingEssuesoftheheart,leadingtoacondiEonknownasprostheEcvalveendocardiEs.TheprimaryorganismsresponsibleforthiscondiEonareS.epidermidis,S.aureus,Streptococcusspp.,gram-negaEvebacilli,diphtheroids,enterococci,andCandidaspp.Theseorganismsmayoriginatefromtheskin,otherindwellingdevicessuchascentralvenouscatheters,ordentalwork.

BiofilmsandContactlenses•  BacterialbiofilmformaEon

oncontactlensesandcontactlensstoragecasesmaybeariskfactorincontactlens-associatedcornealinfecEons.StudieshaveshownthatcontaminaEonoflenscasesbybacteria,fungi,andamoebaeiscommonwith20%to80%oflenswearershavingacontaminatedlenscase.

UrinarycathetersandBiofilms

•  Urinarycathetersaretubularlatexorsiliconedevices,whichwheninsertedmayreadilyacquirebiofilmsontheinneroroutersurfaces.TheorganismscommonlycontaminaEngthesedevicesanddevelopingbiofilmsareS.epidermidis,Enterococcusfaecalis,E.coli,Proteusmirabilis,P.aeruginosa,K.pneumoniae,andothergram-negaEveorganisms.Thelongertheurinarycatheterremainsinplace,thegreaterthetendencyoftheseorganismstodevelopbiofilmsandresultinurinarytractinfecEons.

Biofilmsandindwellingmedicaldevices

•  Biofilms on indwelling medical devices may becomposed of gram-posiEve or gram-negaEvebacteriaoryeasts.Bacteriacommonly isolatedfromthesedevicesincludethegram-posiEveEnterococcusfaecalis, Staphylococcus aureus, Staphylococcusepidermidis, and Streptococcus viridians; and thegram-negaEve Escher ichia col i , K lebs ie l lapneumoniae, Proteus mirabilis, and Pseudomonasaeruginosa.

IndwellingcathetersandBiofilms*•  Central venouscatheters, the referencemethod forquanEficaEonofbiofilmsoncatheterEpsistheroll-plate technique, inwhich the Ep of the catheter isremoved and rolled over the surface of anonselecEve medium. QuanEficaEon of the biofilmdependson thenumberof organisms recoveredbycontact with the agar surface. Biofilm-associatedcells on the inner lumen of the device are notdetectedwiththismethod,whichhaslowdiagnosEcsensiEvity and low predicEve value for catheter-relatedbacteraemia.

IndwellingcathetersandBiofilms*

•  InaddiEon,thismethodcannotdetectmorethan1,000colony-formingunits(CFU)perEp.AmethodthatusedsonicaEonplusvortexingasameansofquanEfyingbiofilmsoncatheterEpsshowedthatalevelof104CFUperEpispredicEveofcatheter-relatedsepEcaemia

*BiofilmsandDevice-AssociatedInfec:onsRodneyM.DonlanCentersforDiseaseControlandPreven:onAtlanta,Georgia,USA

An:bio:ctherapyalonemaynotcure?

•  AnEmicrobial agents areadministered during valvereplacement and wheneverthepaEenthasdentalworkt o p r e v e n t i n i E a laYachment by killing allmicroorganisms introducedinto the bloodstream. Aswith biofilms on otheri n d w e l l i n g d e v i c e s ,rela:vely few pa:ents canbe cured of a biofilminfec:on by an:bio:ctherapyalone

Biofilmsneedhigherconcentra:onofAn:bio:cs

•  BiofilmsareremarkablydifficulttotreatwithanEmicrobials.AnEmicrobialsmaybereadilyinacEvatedorfailtopenetrateintothebiofilm.InaddiEon,bacteriawithinbiofilmshaveincreased(upto1000-foldhigher)resistancetoanEmicrobialcompounds,eventhoughthesesamebacteriaaresensiEvetotheseagentsifgrownunderplanktoniccondiEons.

BiofilmshelpGenetransfer

•  Biofilmsincreasetheopportunityforgenetransferbetween/amongbacteria..Genetransfercanconvertapreviousavirulentcommensalsorganismintoahighlyvirulentpathogen.

Biofilmscontributefornewphenotypes

•  Bacteriaexpressnew,andsomeEmesmorevirulentphenotypeswhengrowingwithinabiofilm.SuchphenotypesmaynothavebeendetectedinthepastbecausetheorganismsweregrownonrichnutrientmediaunderplanktoniccondiEons.ThegrowthcondiEonsarequitedifferentparEcularlyinthedepthsofbiofilms,

Biofilms–ProtectsfromPhagocytosis

•  PhagocytesareunabletoeffecEvelyengulfabacteriumgrowingwithinacomplexpolysaccharidematrixaYachedtoasolidsurface.Thiscausesthephagocytetoreleaselargeamountsofpro-inflammatoryenzymesandcytokines,leadingtoinflammaEonanddestrucEonofnearbyEssues.

Currentobjec:vesonBiofilmresearch

•  oDevelopmentofimprovedimagingofbiofilmsinsitu;oDevelopmentofimprovedclinicallyrelevantinvitroandinvivomodelsofbiofilmsunderspecificinvivocondiEonssuchasflowrate,nutrientcontent,andtemperature;

•  oDevelopmentofbeYerprobes(geneEc,metabolic,andimmunological)forreal-Emeanalysis;oStudiesofquorumsensing/signalingmolecules;

Currentobjec:vesonBiofilmresearch

•  oFurthercharacterizaEonofbiofilm-specificgeneexpression;

•  oStudiesoftheexchangeofgeneEcmaterialwithinbiofilms;

•  oStudiesoforganiccontaminantsonsubstrata,andtheirinfluenceonbiofilmstructure;oDevelopmentofnovelapproachestocontrolpathogenicbacteriaby,forexample,devisingstrategiestofavourgrowthofnon-pathogenicmicroorganismsinbiofilmcommuniEes;

CurrentobjecEvesonBiofilmresearch

•  oStudiesofpathogenicmechanismsofmicrobesgrowinginbiofilms;oElucidaEonofmechanismsofresistanceofbiofilmstoanEmicrobialagents;oStudiesofhostimmuneresponses,bothinnateandadap:vetobiofilms;

Currentobjec:vesonBiofilmresearch

•  InstudiesofinfecEouslungdiseaseincysEcfibrosis;oStudiesonthepotenEalofdiagnosEcproceduressuchasBronchoalveloarlavage(IrrigaEon)andbronchoscopytodisturblocalbiofilmfloraandinoculatedistantlocaEons;

•  oDevelopmentofmathemaEcalmodelsandcomputersimulaEonsofbiofilms;oDevelopmentofthemethodologyfortheprevenEonandcontrolofbiofilmsfromcatheters,waterunitlines,andotherclinicallyimportantsolidsurfaces;.

SearchingforalternaEves–Tissueengineering

•  Role of biofilms in mulEple pathologies and thedifficultyinresolvingthesepathologiesspeakstotheimportance of developing means of replacing orenhancing the therapies already in use. The use ofsyntheEc materials in the body ranges fromcatheters to mesh to stents to heart valves andbeyond. UnEl the development of viable andpracEcalEssueengineering, thennumberandtypesofapplicaEonsinwhichsyntheEcmaterialsareusedwillconEnuetoincrease.

EmergingMethods•  Severalresearchersare

findingsoluEonsforthecureofBiofilms,yetitisexperimental,withadvancesinmolecularbiologybeYermodeltreatmentscanbeidenEfiedtoreducetheproblemofBiofilminterferenceinAnEbioEctherapy.