MRSA is a dangerous infectious disease caused by resistant strains of Staphylococcus aureus (Golden Staph.). Full name of this disease is Methicillin-resistant Staphylococcus aureus infection.

1. MRSA ANTIBIOTIC RESISTANCE MECHANISM
MRSA isa dangerousinfectiousdiseasecausedbyresistantstrainsof Staphylococcusaureus(Golden
Staph.).Full name of thisdisease isMethicillin-resistantStaphylococcusaureusinfection.
Differenttypesof antibacterials(exceptdrugsincludedinthe groupof beta-lactamantibiotics) canbe
usedto treatresistantstaphinfection.Itshouldbe notedthatabouthalf of all drugsusedto treat
bacterial infectionsare beta-lactamantibiotics.Therefore,tochoose antibioticsforMRSA is muchmore
difficultthanforthe treatmentof othertypesof bacterial infections.WhentreatingMRSA,itis
importantto choose antibioticsthatwork,helpquicklygetridof the infectionandpreventtransmission
of dangerous bacteriafromaninfectedpersontohealthypeople.
Before startingantibiotictherapy,itisnecessarytofindoutwhattissuesandorgansare alreadyinfected
withStaphylococcusaureus.Incasesif strainsof staphinfectblood,heart,bone tissue,skin,orlower
respiratorytract,intravenously(IV) drugsforMRSA can be administered.IV antibioticsare usedtotreat
severe MRSA inpatientswhohave failedtorespondtootherdrugs.IV injectionsorVancomycin
infusions(Vancoled,Vancor,Vancocin,Lyphocin) are usedasthe first-line therapyof MRSA.
For successfullyMRSA cure,thisIV antibioticcanbe administeredincombinationwithother
antibacterialsfromthe rifamycingroup(e.g.,Rifapentine,Rifampin,Rifabutin)oraminoglycosidegroup
(e.g.,Gentamicin,Kanamycin,Neomycin,Paromomycin,Spectinomycin,Streptomycin,Tobramycin).
Unfortunately,notall patientswithMRSA manage tocure a dangerousinfectiousdiseaseafterthe first
course of antibiotictherapy.Forthe re-treatmentof MRSA,IV infusionsof antibioticsLinezolid,
Daptomycinor Tigecyclinecanbe used.All the listedantibioticsforMRSA reallyworkandhelpquicklyto
stopthe developmentof infection.However,veryoften,MRSA iscomplicatedbyothertypesof
bacterial infections. Insuchcases,patientsshouldbe prescribedwithdrugscontainingseveral
antibacterial agents.Advantage of antibacterial cocktail drugsisthattheiractive ingredientshave
differentmechanismsof action.Therefore,drugsforMRSA containingtwoantimicrobial agentshave an
extendedrange of antibacterial activity.
One of the mostprescribedcombinationantibioticsforMRSA is Synercid.Thisinjectable drugincludes
antibacterial agentsDalfopristinandQuinupristin.
It shouldbe notedthatinjectiontherapyof MRSA isveryeffective,butisveryexpensive.Therefore,
manypatientshave touse cheap oral antibioticsforMRSA treatment.
Some of the mosteffectiveoral drugsforMRSA are Bactrim, Cotrim, Septra,Sulfatrim, Sulmeprim
(containantibacterial agentsTrimethoprimandSulfamethoxazole),aswell asZyvox oral tablets(contain
antibacterial agentLinezolid).Lesseffective oral antibioticsforMRSA treatmentare Clindamycin
(Cleocin,Calindamin,Clindamyk),Erythromycin(Erymax,ERYC,Eryped,Erythrolar).Particularattention
shouldbe paidto oral antibacterialsfromthe groupof quinolones(suchas,Ciprofloxacin,Levofloxacin,
Moxifloxacin,Ofloxacin,Norfloxacin,Gemifloxacin).Drugsof thisgrouphave a bactericidal effect.
Therefore,theycan be administeredtotreatMRSA inpatientswithbacteremia.

2. If you wantto buy antibioticstotreatMRSA at the lowestprice,youcanfindcheaporal and IV
antibacterialsononlinepharmacy.Topurchase drugsfor the treatmentof Methicillin-resistant
Staphylococcusaureusinfection(MRSA) online,aprescriptionisnotrequired.Therefore,youcanmake
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DefinitionofMRSA
By the CDC’s definition,MRSA infectionisclassifiedascommunity-associatedinindividualswhohave
not beenhospitalizedorundergone amedical procedurewithinthe past12 months.Previously,
infectionwithMRSA typicallyoccurredinhospitalizedpatients,knownashealthcare-associatedMRSA
infection.Todifferentiatethese strains,patientswithCA-MRSA infectionmustmeetone of the
followingcriteria:
Edward A. Bell
 diagnosisof MRSA was made inthe outpatientsettingorbyculture positive forMRSA within48
hoursafterhospital admission;
 no medical historyof MRSA infectionorcolonization;
 no medical historyinthe pastyearof hospitalization,admissiontoanursinghome,skilled
nursingfacility,orhospice,orsurgery;
 no permanentindwellingcathetersormedical devicesthatpassthroughthe skinintothe body.
OtherdifferencesbetweenHA-MRSA andCA-MRSA exist.Fortunately,CA-MRSA isolatesare usually
susceptibletomore antibioticagentsthanHA-MRSA isolates,whichtendtobe resistanttomultiple
antibiotics.CA-MRSA isolatesare more likelytoproduce specificvirulence factorsorexotoxins.An
importantvirulence factorproducedbymanyMRSA strainsisPanton-Valentine leukocidin(PVL),a
cytotoxin.InfectionwithaPVL-producingstraincanresultinseriousclinical illness,suchasosteomyelitis
or hemorrhagicnecrotizingpneumonia.
Illnessdue toCA-MRSA mostcommonlyresultsinskinandsofttissue infections,suchascellulitis,
abscessformationorfolliculitis.Patientsmayinitiallypresenttoprimarycare clinicianscomplainingof
“spiderbites.”However,CA-MRSA infectionmayalsoresultinseriousorfatal disease.Case reportsor
seriesof necrotizingpneumonia,empyema,osteomyelitisorsepsisoccurringinadultsandchildrenhave
beenpublished.In1999, the CDC publishedcase reportsof fatal CA-MRSA infectioninfourinfantsand
children.
Genotype differences
Genotypesof CA-MRSA strainsare distinctfromHA-MRSA isolates.The mecA gene instaphylococci is
responsible forresistance tobeta-lactamantibiotics.The mecA gene istransportedonamobile genetic
elementknownasastaphylococcal cassette chromosome(SCC).Five SCCmeccomplex typeshave been
foundforStaphylococcusaureus.

3. HA-MRSA strainscontainprimarilySCCmectypesI,IIand III.These genesare associatedwithresistance
to multiple drugclasses,inadditiontobeta-lactamantibiotics.SCCmectypesIV andV encode for
resistance tobeta-lactamantibioticsandare foundprimarilyinCA-MRSA isolates.
AnotherimportantcharacteristicdifferentiatingCA-MRSA strainsfromHA-MRSA strainsisthe
productionof unique toxinsandvirulence factors.Analyseshave revealeddifferinggenesandtoxins
isolatedfromCA-MRSA strainsthathave notbeenfoundinHA-MRSA isolates.A clinicallysignificant
virulence factorunique toCA-MRSA strainsisthe PVLtoxin.Thiscytotoxindamageshumanleukocytes
and can produce severe tissue necrosis.Case reportsof previouslyhealthychildrenandadultsaffected
withCA-MRSA infectionandthe resultingnecroticclinical manifestations,whichhave beenfatal insome
cases,have been published.Althoughthe true prevalence of PVLtoxinproductioninCA-MRSA isnot
known,some reportsindicate thatthe majorityof CA-MRSA isolatesare able tosecrete thishighly
potenttoxin.The mostcommonCA-MRSA clone circulatinginthe UnitedStates,USA300,carries the
genesencodingPVL.However,the USA 300 CA-MRSA clone isbeingincreasingrecognizedasa
nosocomial pathogenandsothe molecularcharacteristicsof CA-MRSA andHA-MRSA strainsare
becomingblurred.
Antibiotictreatment
Due to the genotypicdifferencesdescribedabove,CA-MRSA isolatesare primarilyresistanttobeta-
lactam antibiotics(penicillins,cephalosporins,carbapenems) andmacrolides.Thus,additional treatment
optionsare available toclinicianstreatingCA-MRSA infection. However,nodatafrom controlledtrials
are available assessingwhichantibioticsare mostlikelytobe effectivewhentreatinginfantsand
children.Dataavailable come primarilyfromcase reportsandretrospectivestudies.Treatmentchoice is
guidedby strain-specificantibioticsusceptibilities,clinical severity,patientallergystatus,cost,
tolerabilityandage.
Initiationof antibiotictherapymaynotbe necessaryinall childrenwithskinandsofttissue infections
causedby CA-MRSA.Lee andcolleaguesdescribedanobservationalstudyof 62 children(meanage 5.5
years) withculture-provenCA-MRSA skinandsofttissue abscessinfection.All childrenreceived
antibioticsand96% of childrenreceivedwoundincisionanddrainage.Initialantibiotictherapyfor62
children,priortoculture results,consistedof anineffective antibiotic(baseduponsusceptibility
studies).For37 children,therapywasnotchangedtoan antibiotictowhichthe pathogenwas
susceptible,whereastherapywaschangedtoanappropriate antibioticfor21 children.
There wasno difference inoutcome inchildrenwhoreceivedanappropriate antibioticcomparedwith
childrenwhodidnotreceive anappropriate antibiotic.Of the fourchildrenhospitalizedonthe first
follow-upvisit,none hadreceivedanappropriate antibiotic.A significantpredictorof hospitalization
was initial lesionsize –childrenwithalesionmore than5 cm were more likelytobe admitted.Receipt
of an initial antibiotictowhichthe CA-MRSA isolate wasnotsusceptible wasnota significantpredictor
of hospitalization.Thus,incisionanddrainage withoutadjunctive antibiotictreatmentwasaneffective
therapyinchildrenwithCA-MRSA skinandsofttissue abscessinfectionwhenthe lesionwasfivecmor
less.Otherpublishedstudieshave alsoconcludedthatincisionanddrainage,withoutantibiotictherapy,

4. can be employedassuccessful treatmentof skinandsofttissue abscessformation,includingCA-MRSA
infection.
Oral antibioticchoicesmostlikelytobe usedbypediatriccliniciansinclude clindamycin,trimethoprim-
sulfamethoxazole,doxycycline,minocycline,rifampinandlinezolid.Datadescribingthe effectivenessof
these agentsinchildrenwithCA-MRSA infectioncome primarilyfromobservationalstudiesandcase
reports.Data are notavailable fromcontrolledtrials,andthusmore definitive treatment
recommendationsandguidelinesare notcurrentlyavailable.The 2006 RedBook listsTMP-SMXor
clindamycinasantibioticchoicesforskin/softtissue infectionorpneumonia,andvancomycinforlife-
threateninginfection.
TMP-SMX,clindamycin,vanco
TMP-SMX isa viable initial antibioticforCA-MRSA infection,asmany,butnotall,isolateshave been
reportedtobe susceptible tothisagent.Documentationof the effectivenessof TMP-SMXcomesfrom
case reportsandanecdotal recommendations.Sensitivitystudiesdocumentingthe susceptibilityof CA-
MRSA to TMP-SMX shouldbe obtainedwithitsuse.Because TMP-SMXcontainsasulfonamide
antibiotic,itshouldnotbe usedinchildrenwithahistoryof a documentedtrue allergicreactionto
previoussulfonamide use.AsCA-MRSA infectionmayalsooccurin newborns,cautionshouldbe used
whenprescribingTMP-SMXinthese patients.AsTMP-SMXmay displace bilirubinfromalbuminbinding
sites,thisantibioticshouldnotbe usedinnewbornswithincreasedbilirubin.Because TMP-SMXdoes
not provide adequate activitytowardgroupA streptococcus,itshouldnotbe usedif thispathogenis
suspected(eg,infectionassociatedwithlymphangitis,concomitantstreptococcal pharyngitis,erysipelas)
or is grownuponculture.
Clindamycinisanotherantibioticfrequentlyrecommendedasaninitial therapeuticoption.MostCA-
MRSA isolatesare susceptible toclindamycin.However,itisimportantthatinducible resistancebe
testedforwhenusingclindamycin.Resistance maydeveloprapidlywithclindamycinuse,despite an
initial sensitivityreportindicatingthatthe MRSA isolate issusceptible.Most,if notall,microbiology
laboratoriescanutilize the diskdiffusionmethod(D-zone test)totestforinducible macrolide-
lincosamide-streptograminB(MLSB) resistance.Clindamycinshouldnotbe usedif the D-testispositive,
whichindicatesinducibleresistance.Clindamycinisaviable optionforinfantsagedyoungerthan2
monthswithCA-MRSA infection.Clindamycinisavailable inliquidformation,althoughitisnot
particularlypalatable.Parenthetically,manypharmaciesare able toflavorliquidmedicationproducts
withcommerciallyavailable flavoringsystems.
Vancomycinisgenerallyconsideredthe drugof choice forsevere CA-MRSA infections.AlthoughMRSA is
usuallysensitivetovancomycin,strainswithintermediate susceptibility,or,more rarely,resistant
strainshave beenreported.
What Is the Prognosisof MRSA Infections?

5. Accordingto the U.S. National Institutesof Health,the outcome (prognosis) of MRSA infectionvaries
accordingto the severityof the infectionandthe general conditionof the personwhohasthe infection.
People withgoodgeneral healthwhohave mildCA-MRSA thatisappropriatelytreatedrecoverinalmost
everycase.Mildskininfectionsandevensomemoderate infections(boils,smallabscess) canhave an
excellentprognosisif treatedearlyandeffectively.Othermore seriousorextensive MRSA infections
have a range of prognoses(outcomes) fromgoodtopoor.MRSA pneumoniaandsepsis(blood
poisoning) have highdeathrates.The calculateddeathrate of invasive MRSA isabout20%.
Data are sparse on the on recurrence of MRSA infections.The recurrence rate of MRSA infectioninmild
casesis thoughtto be verylow,butsome investigatorsreportthatpatientsmaybe carriersforup to 30
months,soit ispossible foracarrier to have a contagiousperiodforthislengthof time.One groupof
investigatorsreportsa21% recurrence rate inHIV patientsnine monthsafterthe initial diagnosis.Other
investigatorsreportarecurrence rate of 41% inindividualswithMRSA skin infections.Most
investigatorsagree thatstricthygienehelpsreduce the riskof recurrentinfections.
As mentionedabove,complicationsof MRSA can be seriousandinclude sepsis,pneumonia,organ
damage,tissue lossandscarringdue to necessarysurgery. Additionally,aseriouscomplicationsof
antibiotictreatmentisintestinal infectionbythe anaerobicorganismClostridiumdifficile.Thisorganism
and the problemsitcausesmeritanotherarticle (see reference 4);it,too,istreatable butitmay
markedlyextendthe recoverytime foraMRSA-infectedpatient
Doxycycline,minocycline,linezolidandrifampin
Doxycycline andminocyclinehave beenreportedinasmall numberof adultcase reportsto be effective
therapyforMRSA infection,includingskinand softtissue infectionscausedbyCA-MRSA.Asbothof
these agentsare membersof the tetracycline class,theyshouldnotbe usedinchildrenagedyounger
than 9 years.No data are available fortheiruse inchildren.Minocycline mayrarelycause significant
adverse effects.
Linezolid(Zyvox)isaunique antibiotic,amemberof the oxazolidinone class.Linezolidprovidesgoodin
vitroactivitytowardMRSA, althoughresistance hasbeenreported.Dataonitsuse and effectivenessin
treatingCA-MRSA are limited.AslinezolidisFDA-labeledforuse innewborninfantsandolder,thisagent
isan optionfor veryyoungpatients.Linezolidshouldnotbe usedinitiallyformildCA-MRSA treatment
as it isexpensive andislimitedbyitsadverse effectprofile,includingthrombocytopeniaandperipheral
neuropathy.Pyridoxine atadosage of 50 mg dailymaymodifylinezolid-inducedthrombocytopenia.
Linezolidcanbe usedforseriousinfectionandisequivalentinefficacytovancomycinforseriousMRSA
infection.Linezolidisavailableinanoral liquidformulationandintravenousformulation.
An importanttheoretical butunprovenbeneficial effectof linezolidandclindamycinmaybe the ability
of these agentstomodifyCA-MRSA toxinproduction.A case reportpublishedin 2005 (Micek) described
fouradultswithsevere respiratoryCA-MRSA infection,inwhichall the isolateswere positive forPVL.
Three patientsfailedtherapywithvancomycinbutrespondedtolinezolidorclindamycin.Aslinezolid
and clindamycinbothfunctiontoinhibitproteinsynthesis,thismechanismmaybe valuableinmodifying
exotoxinproduction.

6. RifampinmaypossessgoodinvitroactivitytowardCA-MRSA.Case reportshave beenpublished
describingthe use of rifampinincombinationwithanotherantibiotic,suchasTMP-SMX,clindamycin,or
doxycycline/minocycline.There are nodata documentingincreasedefficacybyaddingrifampin
comparedwithsingle drugtherapy.Rifampinshouldnotbe usedasmonotherapyasresistance may
developrapidly.Asrifampinisapotenthepaticdrugmetabolizingenzymeinducer,the potential for
drug-druginteractionsshouldbe consideredwhenitisemployed.
Conclusion
Culture andsusceptibilitystudiesshouldbe obtainedinall patientswithsuspectedCA-MRSA infection.
Incisionanddrainage ishelpful,anditmaybe sufficientalone withoutantibioticsinmildcases.In
childrenwithmild-moderateillness(eg,febrile,systemicsymptoms),itisappropriate toaddsystemic
antibiotictherapy.TMP-SMX,doxycycline/minocyclineorclindamycinare reasonable antibioticstouse
empirically,priortosusceptibilitystudyresults.However,if local orregional CA-MRSA susceptibilitydata
indicate thatresistance toclindamycinisgreaterthan15%,it has beenrecommendedtoavoid using
clindamycinempirically.Treatmentforsevereillnessshouldincludevancomycinorlinezolid.
Clindamycinmaybe usedempiricallyif local resistance patternsare low.Some evidence suggeststhat
therapywithlinezolidorclindamycinmaybe beneficialinPVL-positiveCA-MRSA infection.
Considerationmaybe giventoaddingrifampinorgentamicintovancomycinforseriousillness.When
usingvancomycinempirically,itisappropriate toinitiallyprescribe nafcillinoroxacillinadditionally,as
these agentsprovide more rapidbactericidal actiontowardmethicillin-susceptible Staphylococcus
aureus.Nasal applicationof mupirocinmaybe beneficial insome patientstopreventrecurrence of
infection.However,itislikelythatrecolonizationwill occurshortly.
What Is the Prognosisof MRSA Infections?
Accordingto the U.S. National Institutesof Health,the outcome (prognosis) of MRSA infectionvaries
accordingto the severityof the infectionandthe general conditionof the personwhohasthe infection.
People withgoodgeneral healthwhohave mildCA-MRSA thatisappropriatelytreatedrecoverinalmost
everycase.Mildskininfectionsandevensomemoderate infections(boils,smallabscess) canhave an
excellentprognosisif treatedearlyandeffectively.Othermore seriousorextensive MRSA infections
have a range of prognoses(outcomes) fromgoodtopoor.MRSA pneumoniaandsepsis(blood
poisoning) have highdeathrates.The calculateddeathrate of invasive MRSA isabout20%.
Data are sparse on the on recurrence of MRSA infections.The recurrence rate of MRSA infectioninmild
casesis thoughtto be verylow,butsome investigatorsreportthatpatientsmaybe carriersforup to 30
months,soit ispossible foracarrier to have a contagiousperiodforthislengthof time.One groupof
investigatorsreportsa21% recurrence rate inHIV patientsnine monthsafterthe initial diagnosis.Other
investigatorsreportarecurrence rate of 41% inindividualswithMRSA skininfections.Most
investigatorsagree thatstricthygienehelpsreduce the riskof recurrentinfections.

7. As mentionedabove,complicationsof MRSA can be seriousandinclude sepsis,pneumonia,organ
damage,tissue lossandscarringdue to necessarysurgery.Additionally,aseriouscomplicationsof
antibiotictreatmentisintestinal infectionbythe anaerobicorganismClostridiumdifficile.Thisorganism
and the problemsitcausesmeritanotherarticle (see reference 4);it,too,istreatable butitmay
markedlyextendthe recoverytime foraMRSA-infectedpatient.
MRSA and Pregnancy
If a pregnantwomanisa MRSA carrier, there isnoresearchevidence thatherpregnancywill be
compromised.Ingeneral,MRSA screeningisnotdone routinelyduringpregnancy.However,if awoman
has beendiagnosedpreviouslywithMRSA andishavinga plannedC-section,she hasa highriskfor
complications,hasaMRSA-positivehouseholdmember,orhasbeenhospitalizedinthe lastthree
months,she maybe screenedforMRSA.Some clinicianswill offertreatmenttosuppressthe bacteria;
othercliniciansmaynot,dependingonthe mother’scircumstances.PregnantwomenwhogetMRSA
infectionsare treatedwithantibiotics;if theypassMRSA to theirinfant,the babycan alsobe treated.
Fortunately,seriousMRSA infectionsininfantsare rare.PregnantwomenwithMRSA infectionsshould
be treatedby specialists,usuallyateamconsistingof anob-gynandinfectiousdisease consultant,since
careful choicesinantibioticsandclose follow-upyieldthe bestoutcomesforthe motherandbaby.
How Is MRSA Diagnosed?
Your healthcare providerwill examinethe areaandbe able to run labteststo see if you have MRSA.If
youhave an infectiononthe skin,yourdoctorwill take a culture fromthe infectedarea.Dependingon
your symptoms,yourdoctoralsomighttestblood,urine,orsputum(mucuscoughedupfromthe
respiratorytract).
What Are the Treatments for MRSA?
MRSA istreatable.Bydefinition,MRSA isresistanttosome antibiotics.Butotherkindsof antibioticsstill
work.If youhave a severe infection,orMRSA inthe bloodstream, youwill needintravenousantibiotics.
Unfortunately,there isemergingantibioticresistance beingseenwithsomeof these medications.
Antibiotics,however,aren’talwaysnecessary.If youhave a small skinboil causedbyMRSA, yourdoctor
may justmake an incisionanddrainit.
If you are prescribedantibiotics,follow yourhealthcare provider’sinstructionsprecisely.Neverstop
takingyourmedicine,evenif you’re feelingbetter.If youdon’ttake all of yourmedicine,some of the
staphbacteriamaysurvive,requiringre-treatment.Inadequatetreatmentalsoincreasesthe
developmentof antibioticresistance inthe survivingstaphpopulation.If youstill have staphyoucan
infectsomeone else.
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