brazilian journal of microbiology47(2016)703–705
h tt p : / / w w w . b j m i c r o b i o l . c o m . b r /
Medical
Microbiology
Contamination
of
environmental
surfaces
by
methicillin-resistant
Staphylococcus
aureus
(MRSA)
in
rooms
of
inpatients
with
MRSA-positive
body
sites
E.
Jessica
Ohashi
Kurashige,
Shigeharu
Oie
∗,
H.
Furukawa
PharmaceuticalService,YamaguchiUniversityHospital,Minamikogushi,Ube,Japan
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received7November2014
Accepted8January2016
Availableonline22April2016
AssociateEditor:AnaLúciadaCosta
Darini Keywords: Methicillin-resistantStaphylococcus aureus Curtain Overbedtable
Bedsiderail
Contamination
a
b
s
t
r
a
c
t
Methicillin-resistantStaphylococcusaureus(MRSA)cancontaminateenvironmentalsurfaces
thatarefrequentlytouchedbythehandsofpatientswithMRSAcolonization/infection.
TherehavebeenmanystudiesinwhichthepresenceorabsenceofMRSAcontamination
wasdeterminedbutnostudiesinwhichMRSAcontaminationlevelswerealsoevaluated
indetail.WeevaluatedMRSAcontamination ofenvironmentalsurfaces(overbedtables,
bedsiderails,andcurtains)intheroomsofinpatientsfromwhomMRSAwasisolatedvia
clinicalspecimens.Weexaminedthecurtainswithin7–14daysaftertheyhadbeennewly
hung.Theenvironmentalsurfaceswerewipedusinggauze(moldedgauzeforwipingof
surfacebacteria;100%cotton,4cm×8cm)moistenedwithsterilephysiologicalsaline.The
MRSAcontaminationrateandmean counts(range)were25.0%(6/24samples)and30.6
(0–255)colony-formingunits(cfu)/100cm2,respectively,fortheoverbedtablesand31.6%
(6/19samples)and159.5(0–1620)cfu/100cm2,respectively,forthebedsiderails.NoMRSA
wasdetectedin24curtainsamples.TherateofMRSAcontaminationofenvironmental
surfaceswashighfortheoverbedtablesandbedsiderailsbutlowforthecurtains.Therefore,
atleastuntilthe14thdayofuse,frequentdisinfectionofcurtainsmaybenotnecessary.
©2016PublishedbyElsevierEditoraLtda.onbehalfofSociedadeBrasileirade
Microbiologia.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://
creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
Topreventthe transmissionofmethicillin-resistant
Staphy-lococcusaureus(MRSA)infection,maintainingthecleanliness
ofthehandsofmedicalstaffandthehospitalenvironment
is important.1–4 In particular, maintaining the cleanliness
∗ Correspondingauthor.
E-mail:oie-ygc@umin.ac.jp(S.Oie).
of environmental surfaces that are frequently touched by
patients’hands(overbedtables,bedsiderails,andcurtains)
isnecessary.5,6 Therehavebeenmanystudiesinwhichthe
presenceorabsenceofMRSAcontaminationwasdetermined
on environmentalsurfaces that are frequently touchedby
patientswithMRSAcolonization/infection,butthesestudies
didnotevaluateMRSAcontaminationlevelsindetail.7–12For
http://dx.doi.org/10.1016/j.bjm.2016.04.002
1517-8382/©2016PublishedbyElsevierEditoraLtda.onbehalfofSociedadeBrasileiradeMicrobiologia.Thisisanopenaccessarticle
704
brazilian journal of microbiology47(2016)703–705theestablishmentofinfection,bothcontaminantsand
con-taminantlevelsareimportant.Therefore,weevaluatedboth
therateandthelevelofMRSAenvironmentalcontamination
inthe rooms ofpatients withMRSA colonization/infection
usingthegauze-wipingmethod,whichismoreeffectivethan
theswabmethodforthedetectionofmicroorganisms.13
Materials
and
methods
Duringa1-monthperiodfromAugust1to31,2013,in
Yam-aguchiUniversityHospital(736beds),weinvestigatedMRSA
contaminationoftherooms(curtains,overbedtables,bedside
rails)of24inpatients(age,1–85years)fromwhomMRSAwas
isolatedviaclinicalspecimens.
MRSAwasisolatedfromthefollowingpatientspecimens:
8samples ofopen pus, 5expectorated (aspirated) sputum
samples,3enclosedpussamples,2eardischargesamples,2
pharyngealmucussamples,1tracheotomyswab,1nasal
dis-chargeswab,1vaginal/vulvarswab,and1earswab.Infiscal
yearof2012,therateofMRSAtransmissionatthehospital
was0.5nosocomialMRSAcasesper100hospitaladmissions.
For sampling, the surfacesof the bed curtains,overbed
tables,and bed siderails were wipedusinggauze (molded
gauze for the wiping of surface bacteria; 100% cotton,
4cm×8cm; Sawada Menko Co., Ltd., Tokyo, Japan)
moist-enedwithsterilephysiologicalsaline. Forthebed curtains,
anareaofapproximately10cm×10cmneartheheadsofthe
patientswasexamined.Inaddition,anareaofapproximately
1cm×100cmofthesiderailsofthebedswasexamined,and
anareaofapproximately10cm×10cmoftheoverbedtables
wasexamined.
Thegauzeusedforwipingwasplacedinatubecontaining
3mLofnutrientbroth.Thetubewasultrasonicated(SineSonic
100;IkemotoRikagaku,Co.,Tokyo,Japan)at36kHzfor5min
andswirledfor30s.Eachsamplewasdiluted10-,100-,and
1000-foldinnutrientbroth;0.5mLofeachdilutionandofan
undilutedsamplewereplatedonsalteggyolkagarplates
(Nis-suiPharmaceutical,Co.,Tokyo,Japan).Thesesalteggyolkagar
plateswereincubatedat35◦Cfor48h.Yellowcoloniesonthe
plateswithapearl-ringformationinthesurroundingmedium
wereexaminedbyGram-stainingandthecoagulasetest(for
morphology)(StaphyloLaSeiken;DenkaSeiken,Co.,Tokyo,
Japan)andbyanApiStaph(Analytab Products,Plain View,
N.Y.,USA)todeterminewhethertheywereS.aureus.Staphylo
LaSeikenisbasedontheagglutinationmethodandis
com-posedofalatexsuspensioncoatedwithhumanfibrinogenand
rabbitIgG.
Themethicillinsensitivity ofthecultured S.aureuswas
determined usingMRSAscreeningagar containing6g/mL
oxacillin(NipponBectonDickinson,Co.,Tokyo,Japan).Positive
growthofMRSAwasconfirmedonthescreeningagar.When
10ormorecolonyformingunits(cfu)ofS.aureusculturedon
salteggyolkagarweredetected,10colonieswererandomly
selected,andtheirmethicillinsensitivitywasdetermined.The
MRSAormethicillin-sensitiveS.aureus(MSSA)countpergauze
wipewasquantifiedfromtheratioofmethicillin-resistantto
methicillin-sensitivecolonies.14 S.aureus209P wasused as
qualitycontrol.
Table1–Methicillin-resistantStaphylococcusaureus
(MRSA)contaminationoftheenvironmentalsurfacesin roomsof24inpatientswithMRSA-positivebodysites.
Examineditems (ca.100cm2) Contaminantrate (%)(no.of samples/no.of samples examined) Mean±standard deviation(range)of thecontamination level(cfu/examined item) Overbedtables 25.0(6/24) 30.6±65.6(0–255)
Bedsiderailsa 31.6(6/19) 159.5±396.4(0–1620)
Curtains 0(0/24) 0
a Nineteensampleswereexaminedbecausebedswithoutsiderails
wereusedin5ofthe24patients.
InYamaguchiUniversityHospital,environmentalsurfaces
intheroomsofpatientsfromwhomMRSAwasisolatedvia
clinicalspecimensaredisinfectedbynursesbywipingwithan
80vol%ethanolsolutiononceaday.Thepresent
environmen-talcontaminationsurveywasperformedimmediatelybefore
this routine wiping. Although the 100% polyester curtains
(KingRun,KingrunCo.,Ltd.,Tokyo,Japan)arenotroutinely
disinfected, weexamined themwithin7–14daysafterthey
hadbeennewlyhung.
Results
Table 1shows therates andlevelsofMRSAcontamination
oftheenvironmentalsurfaces(overbedtables,bedsiderails,
andcurtains)intheroomsof24patientsinwhomMRSAwas
detected.MRSAcontaminationwasobservedin6(25%)of24
overbedtablesamplesand6(31.6%)of19bedsiderailsamples
butwasnotobservedin24curtainsamples.ThemeanMRSA
counts (range)/100cm2 were 30.6 (0–255)cfuin theoverbed
tablesamplesand159.5(0–1620)cfuinthebedsiderail
sam-ples.TheMRSAcontaminationrateswerethereforehighfor
theoverbedtablesandbedsiderailsbutlowforthecurtains.
Inaddition,thebedsiderailssometimesshowedaMRSAlevel
of103cfu/100cm2.
Discussion
MRSA can survive for a long period of time in the
environment.14 When the hospital room environment is
contaminated with MRSA, fingers also tend to become
contaminated.MRSAcontaminationoftheenvironment
sur-roundingpatientsmayplayamajorroleinthetransmission
ofMRSAinfection.Therefore,weevaluatedMRSA
contami-nationintheenvironmentsurroundingpatientsfromwhom
MRSAwasisolatedviaclinicalspecimens.Inthisstudy,both
thecontaminationrateandthecontaminationlevelwere
eval-uatedbecausethelatterisalsoimportantinthedevelopment
ofinfection. Wedetermined thatboth the MRSAdetection
ratesofthe overbedtableandbed siderailsamples(25.0%
and31.6%,respectively)andthemeancontaminationlevels
oftheseareas(30.6and159.5cfu/100cm2,respectively)were
high.IntheU.K.,theproposedcriteriaforthecleanlinessof
hospitalenvironmentsincludeanindicatororganismcount
brazilian journal of microbiology47(2016)703–705
705
tablesamplesshowedaMRSAcontaminationlevelof>1cfu.
Overbedtablesandbedsiderailssurroundingpatientsfrom
whom MRSA isdetectedfrom clinical specimensmay
fre-quentlybecontaminatedwithahighlevelofMRSA.
However,noneofthecurtainsampleswerecontaminated
with MRSA in this study. This result was consistent with
thatofanotherstudythatfoundnoMRSAcontaminationin
curtains.5Incontrast,therateofMRSAcontaminationin
cur-tainswasreportedtobe92%(12of13samples)byOhletal.,
15.5%(31of200samples)byKlakusetal.,and28%(14of50
samples)byTrillisetal.16–18 Thedifferencesinthe
contami-nationratemayhavebeenduetotheMRSAdetectionmethod
usedand/orthecurtainmaterial;therefore,furtherstudiesare
necessarytoresolvethediscrepanciesintheseresults.
Basedontheresultsofthisstudy,disinfectionofoverbed
tablesand bed siderails surrounding patients from whom
MRSAhasbeenisolatedisessential.Whenpatientsand
med-icalstafftouchsuchenvironmentalsurfaces,itisnecessary
toregardthemasbeingcontaminatedandtakeappropriate
countermeasures.However,atleastuntilthe14thdayofuse,
frequentdisinfectionofcurtainsmaynotbenecessary.
Meas-uressuchascleaningcurtainsafterapatient’sdischargefrom
theroommaybeadequate.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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