Download Methicillin-Resistant Staphylococcus Aureus (MRSA)

Methicillin-ResistantStaphylococcusAureus(MRSA)
Methicillin-resistantStaphylococcusaureus(MRSA)isatypeofstaphbacteriathatisresistanttocertain
antibioticscalledbeta-lactams.Theseantibioticsincludemethicillinandothermorecommonantibiotics
suchasoxacillin,penicillin,andamoxicillin.Inthecommunity,mostMRSAinfectionsareskininfections.
Bacteriology
Methicillin-resistantStaphylococcusaureus(MRSA)referstoStaphylococcusaureusisolatesthatare
resistanttoallcurrentlyavailableβ-lactamantibiotics(penicillins,cephalosporinsandcarbapenems).
Methicillin-resistantStaphylococcusaureus(MRSA)isanon-sporeforming,grampositivecoccithatis
non-motileandusuallyfoundinclusters.ManyMRSAstrainsproduceexotoxinsincludingstaphylococcal
enterotoxinsA,B,C,D,E,toxicshocksyndrometoxin(TSST-1)andexfoliativetoxinsA,andB.OnceMRSA
becomesendemicwithinahospital,itisrarelyeliminatedandmayeventuallyaccountfor5–50%ofall
nosocomialStaphinfections.
ClinicalManifestations
MRSAinhealthcaresettingsusuallycausesmoresevereandpotentiallylife-threateninginfections,
suchasbloodstreaminfections,surgicalsiteinfections,orpneumonia.Thesignsandsymptomswillvary
bythetypeandstageoftheinfection.Inthecommunity,mostMRSAinfectionsareskininfectionsthat
mayappearaspustulesorboilswhichoftenarered,swollen,painful,orhavepusorotherdrainage.
Theyoftenfirstlooklikespiderbitesorbumpsthatarered,swollen,andpainful.Theseskininfections
commonlyoccuratsitesofvisibleskintrauma,suchascutsandabrasions,andareasofthebody
coveredbyhair(e.g.,backofneck,groin,buttock,armpit,beardareaofmen).
EpidemiologyofTransmission
Atanygiventime,between20and30percentofthegeneralpopulationcarryStaphbacteriaand
/orMRSAontheirhandsorintheirnoses,butarenotill.Transmissionisgenerallybycontactwith
nasalcarriers(30-40%ofpopulation);fromcontactwithdraininglesionsorpurulentdischarges,spread
person-to-personorbyingestionoffoodcontainingstaphylococcalenterotoxin(foodmaybe
contaminatedbyfoodhandlers’hands).Theincubationperiodishighlyvariableandcanbeindefinite
duetocolonization.Mostcommonlytheincubationperiodis4-10days;however,diseasemaynotoccur
untilseveralmonthsaftercolonization.Therelatedincubationintervalbetweeneatingfoodandonset
ofsymptomsisusually2-4hoursbutcanbeasshortas30minupto8hours.
BasicPrevention
TheimportanceofhandhygieneintheeliminationofMRSAtransmissioncannotbeoverstated.Alcoholbasedhandsanitizers(≥70%ethanol)maybehelpfulasanadjunctmethodofhandhygiene,
butshouldnotreplacewashingwithsoapandwater.
Anywoundsthataredrainingorhavepusmustbekeptcoveredwithclean,drybandages.Pusor
otherdrainagefromthewoundcancontainMRSA,somakesurethatthebandagesandtapeusedto
coverthewoundareproperlydiscarded.
Avoidsharingpersonalitems.Bacteriacanbetransferredtoanotherpersonthroughcontact
withitemssuchastowels,razorsorwashclothssotrytoavoidsharingtheseitems.Makesureany
soiledclothingiswashed;waterandregularlaundrydetergentissufficient.
PreventionMeasures
InadditiontoRoutine/StandardPrecautions,ContactPrecautionsshouldbeimplementedwith
patientswhoaresuspectedorconfirmedtohaveMRSA.
• PatientswithsuspectedorconfirmedMRSAmaybeplacedinprivateroomsorcohortwith
otherpatientswiththesameinfection.
• Followhand-hygieneguidelinesbyeithercarefullywashinghandswithsoapandwaterorusing
Alcohol-BasedHandSanitizers(ABHS)aftercontactwithpatientswithinfluenzainfection
• Usegownsandgloveswhenincontactwith,orcaringforpatientswhoaresymptomaticwith
MRSAforallinteractionsthatmayinvolvecontactwiththepatientorpotentiallycontaminated
areasinthepatientsenvironment
• AsymptomaticMRSA-colonizedHCWsrarelytransmitMRSAtopatients.Currentguidelinesdo
notrecommendrestrictingworkactivitiesunlesscolonizedHCWsarefoundtobethesourceof
MRSAtransmission.
EnvironmentalControlMeasures
MRSAhasbeenfoundtosurviveintheenvironmentfrom1to56daysoncommonhospitalmaterials
andonskinfrom30minto38days.PeoplecolonizedwithMRSAcontinuouslyshedintothe
environment.
Hospital-gradecleaninganddisinfectingagentsaresufficientforenvironmentalcleaninginthecontext
ofMRSA.Allhorizontalandfrequentlytouchedsurfacesshouldbecleaneddailyandwhensoiled.The
healthcareorganization’sterminalcleaningprotocolforcleaningofthepatient’sroomfollowing
discharge,transferordiscontinuationofContactPrecautionsshouldbefollowed.Allpatientcare
equipment(e.g.,thermometers,bloodpressurecuff,pulseoximeter,etc.)shouldbededicatedtothe
useofonepatient.AllpatientcareequipmentshouldbecleanedanddisinfectedasperRoutine/
StandardPracticesbeforereusewithanotherpatientorasingleusedeviceshouldbeusedand
discardedinawastereceptacleafteruse.Toys,electronicgamesorpersonaleffectsshouldnotbe
sharedbypatients.
References:
1.PublicHealthAgencyofCanada(PHAC),MaterialSafetyDataSheet–InfectiousSubstances:
Enterococcusfaecalis.
http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/enterococcus-eng.php
2.GuidelinesforEnvironmentalInfectionControlinHealthcareFacilities,CDC.MMWRJune2003,
Vol52,NoRR-10
3.BestPracticesforCleaning,DisinfectionandSterilizationinAllHealthCareSettings,Provincial
InfectiousDiseasesAdvisoryCommittee(PIDAC),February2010
4.GuidelineforIsolationPrecautions:PreventingTransmissionofInfectiousAgentsinHealthcare
Settings,HICPAC,2007
5.GuidetotheEliminationofMethicillin-ResistantStaphylococcusaureus(MRSA)Transmissionin
HospitalSettings,2ndEd.APIC2010.