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University of Groningen
Electric current induced prevention of biofilms on stainless steel
van der Borden, Arnout
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Publication date:
2005
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Citation for published version (APA):
Borden, A. J. V. D. (2005). Electric current induced prevention of biofilms on stainless steel Groningen: s.n.
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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.
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