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University of Groningen Electric current induced prevention of biofilms on stainless steel van der Borden, Arnout IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2005 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Borden, A. J. V. D. (2005). Electric current induced prevention of biofilms on stainless steel Groningen: s.n. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 17-06-2017 Summary lnfection of percutaneousbiomaterialsimplants, such as fixation frames used for the repair of complicatedÍiactures in orlhopaedics,is a major complication that almost inevitablyleadsto replacernent of the implant.If nothingis undeÍaken,the infection can ultimately lead to osteomyelitiswith devastatingeÍïectson bone and surroundingtissue. inÍèctions,since As antibiotictherapyusuallyhas little impacton biomaterials-associated the bioÍilm rnodeof growth offers protection,it is the aim of this thesisto investigatethe pr-evention pins and screwsas used in the externalfixator, of infectionon percutaneous with the aid of an electriccuffent,as presentedin chapter I To study bacterialadhesion,a parallelplate flow chamberwas used,which allows the in situ observationundercontrolledhydrodynamicconditions.In the flow chamber,bacteria w'ereallowed to adherefrom a flowing suspensionof physiologicalionic strengthto a stainlessstcel surÍàce,aÍter which the suspensionwas replacedby a bacterium lree solutionwith a speciÍiedionic strength(0.5 to 150mM potassiumphosphate).In chapter 2 DC currentsrangingfrom 15 to 125 pA were appliedto induce bacterialdetachment. Initial detachmentdecreasedwith increasingionic strengthat 100 ptA. The percentage detachmentachievedby applicationof an electriccunent after2.5 h was highest(95 %) in I mM potassiumphosphateand decreasedto l5 'J/owhen the ionic strengthexceeded 40 mM. The electric current did not significantlyaffect the percentagedetachrnent,but initial detachmentratesincreasedwith increasingcurrentfrom 1000 cm-2s-rat 15 pA to epidermidisand 7000 crn-2s-r at 125 pA. Although diÍïerent isolatesof Staphylococcus Stctphylococ'cu.t aureus showed different pattems of current induced detachment,all strains could be stimulatedto detach.The results of this study define ionic strength conditions and electric currents yielding staphylococcaldetachmentfrom surgical stainlesssteel and therewith point to a pathway for the treatnlentand prevention of percutaneous metal-irnplantinfection. However, DC currentsproduce more power that has to be dissipatedby the skin as comparedto alternatingcurrents.Also, an excessof ions on the steelcan causenegative osteogenesisand Ílxation results. ThereÍbre, in chapter 3 the airn was to examine whetherdetachmentof S. epidermidlsHBH 276 írom stainlesssteelsurfacesin a parallel plate flow chambercan alsobe stimulatedusingelectricblock currents.Block currentsof 15, 60 and 100 ptA with different Íiequencies(0.1 to 2 Hz) and duty cycles(5 to 50 %) of were appliedto inducebacterialdetachment.100 pA block currentscausedetachmerrt about 76 % of adhering staphylococcifrom stainlesssteel, whereas in addition the t) Summary remainingbacteriaare less viable, as determinedby culturing the remainingbacteriaon agar plates. Therewith, block current induced detachmentof adhering bacteria Íiom stainlesssteel appearsto be an equally promising ntethod to prevent infection of orthopaedictixation pins and screwsthanapplicationof DC currents. It is klow that initially adheringbacteriaadheremore reversiblythan bacteriagrowing in the later stagesof bioÍilrn formation. Hence, it is the airn of chapter 4 to examine wlrethera growing S. epidermidi.sHBH 276 biofilm can be stimulatedto detachfrom surgicalstainlesssteelusingelectriccurrents.In separateexperirnents, four currentsof60 pA DC, 100 pA DC,60 pA block (50 % duty cycle,1 Hz) and 100pA block (50 oÁduÍy cycle, I Hz) u'ere applied Íbr 360 mir-rto stimulatedetachnrentof a S. epidermidi.t biofilm, grown fbr 200 rnin. A 100 pA DC currentyielded a detachmentof 78 %, wlrereasthe 100 pA block currentunderthe sameexperimental conditionsyieldedonly 3l % detachment.The sarnetrend r,vasfound fbr 60 uA rvith 37 oÁdetachmentfor a DCI cunent and 24 oÁ Ïor a block cunent. Bacteriaremaining on the surfaceaÍïer current applicationwere lessviablethanprior to currentapplication,as demonstrated by contbcal laser scanning microscopy. Cioncluding,these results suggest that DC currents are preÍèrredin curing infections.The three chaptersr,vithin vitro data were encouraeing enoughto testthe applicationofan electriccurrentin vivcl.In chapter5, electriccurrents appliedto infectedstainlesssteelpins were evaluatedin a goat model.Threepins were insertedinto the lateral right tibia of six goats, of which one solely served Íbr extra support,one was taken as a control and anotherwas infectedu'ith S. epidernitli,sHBH 216.Pin siteswereexamineddaily and aÍier21 daysthe anirnalswerekilled and the pins takenor.rt. lnÍèction developedin 100 % of the control pins whereasthe pins in the current group showedno infèctionin flawlessexperinrents, and only in caseof cunent application problems.tcmporaryinlèctionwasseen. In thegeneraldiscussion, chapter6, therole of EPSand irrigationon detachment andthe antimicrobialresistancewere discussedupon applicationof an electric curreut. Furthenr.rore, the electrodedesignwas discussedwith respectto irnplantationin muscle and rnovingtissue.Finally, someremarkswith respectto futureresearchwere rnade. 74