USF Libraries
USF Digital Collections

Risk factors for pediatric community-acquired methicillin-resistant Staphylococcus aureus

MISSING IMAGE

Material Information

Title:
Risk factors for pediatric community-acquired methicillin-resistant Staphylococcus aureus
Physical Description:
Book
Language:
English
Creator:
Kessler, Melissa Gail
Publisher:
University of South Florida
Place of Publication:
Tampa, Fla.
Publication Date:

Subjects

Subjects / Keywords:
antibiotic resistance
MRSA
bacterial infections
infection control
hospital epidemiology
Dissertations, Academic -- Public Health -- Masters -- USF   ( lcsh )
Genre:
government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
ABSTRACT: Methicillin-Resistant Staphylococcus aureus (MRSA) began as a nosocomial infection due to overuse of antibiotics. Several previous studies have reported an increase in this infection in adult patients who have not been hospitalized. It has also been reported that there is an increase in MRSA in children. Some of these children became infected even though they were not at high risk for the infection. After approval from the All Children's Hospital Institutional Review Board (IRB), a cross sectional study was conducted with pediatric admissions and pediatric emergency room visits to determine the characteristics of Methicillin-Sensitive Staphylococcus aureus and MRSA. During this study, a review of 672 medical charts was conducted. The study participants ranged in age from newborns to 18 years of age. In order to be enrolled in the study, the subjects' cultures were collected either as outpatients or within 72 hours of admission. The data that was collected from each chart included age, race/ethnicity, gender, type of infection, preexisting medical conditions, and risk factors for infection. The potential risk factors include antibiotic use, previous surgery or outpatient procedure, previous MRSA infection, immunotherapy, community worn device, and residence in a facility. Statistical analysis was conducted using Epi Info and SAS software packages. In regards to demographic characteristics, black children are 2.98 times more likely to have an MRSA infection than white children. Gender and age were not risk factors for the development of the infection. The risk factors that were significant in whites were home health care (OR= 6.12, CI= 5.16, 7.08), community worn device (OR= 2.28, CI= 1.67, 2.89), previous hospitalization (OR= 2.43, CI= 1.95, 2.91), previous MRSA infection (OR= 3.69, CI= 2.90, 4.48), and previous surgery (OR= 2.02, CI= 1.51, 2.53). In blacks, females were more likely to have MRSA (OR= 2.57, CI= 1.73, 3.41). This finding may be due to the small sample size of black children in the study. Of the analyzed risk factors, home health care (OR= 2.95, CI= 1.11, 4.79), community worn device (OR= 2.85, CI= 1.71, 4.01), previous hospitalization (OR= 1.98, CI= 1.13, 2.83), previous surgery (OR= 2.79, CI= 1.79, 3.79), and previous antibiotic (OR= 5.60, CI= 4.66, 6.54) use were all significant risk factors in blacks. Effect modification was tested between race and all risk factors. Race was an effect modifier only for the risk factor of previous antibiotic use (pvalue =.02). Adjustment of confounding was performed for each race due to the presence of effect modification. After the adjustment for confounding in whites, only home health care (OR=4.37 CI= 1.55, 12.32), previous MRSA infection (OR= 2.86 CI= 1.16, 7.05), and previous hospitalization (OR= 2.00 CI= 1.14, 3.50) remained statistically significant. In blacks, after adjustment of confounding, only previous antibiotic use (OR= 5.13 CI= 1.75, 15.08) remained significant. Adjustment for confounding was also preformed on the total risk factors model. A dose response relationship was present with increasing risk factors present.
Thesis:
Thesis (M.S.P.H.)--University of South Florida, 2004.
Bibliography:
Includes bibliographical references.
System Details:
System requirements: World Wide Web browser and PDF reader.
System Details:
Mode of access: World Wide Web.
Statement of Responsibility:
by Melissa Gail Kessler.
General Note:
Title from PDF of title page.
General Note:
Document formatted into pages; contains 61 pages.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 001469351
oclc - 55520417
notis - AJR1105
usfldc doi - E14-SFE0000253
usfldc handle - e14.253
System ID:
SFS0024948:00001


This item is only available as the following downloads:


Full Text

PAGE 1

RiskFactorsForPediatricCommunityAcquiredMethicillinResistantStaphylococcusaureusbyMelissaGailKesslerAthesissubmittedinpartialfulllmentoftherequirementsforthedegreeofMasterofScienceinPublicHealthDepartmentofEpidemiologyandBiostatisticsCollegeofPublicHealthUniversityofSouthFloridaCo-MajorProfessor:HeatherStockwell,Sc.D.Co-MajorProfessor:RogerSanderson,M.A.YouguiWu,Ph.D.DateofApproval:March24,2004Keywords:antibioticresistance,mrsa,bacterialinfections,infectioncontrol,hospitalepidemiologycCopyright2004,MelissaGailKessler

PAGE 2

DEDICATIONTomylovinghusband,ScottforallyourhelpwithSASandLaTeXandforyourpatience,support,andcomfortingwords,anddryingmytears.Tomyparentsforalltheirsupportandhelpingmeto"notscrewup"and"keepmyfocus."Tomybrother,Ericthanksforlisteningtomytrialsandtribulationsandprovidingmesomemuchneededcomicrelief.ToKelly&Will,thanksforalltheendlesshoursofproofreadingandrehearsalfordefense.ToAndreas,thanksforallyoursupportandkindwords.ToFoundations,thanksforlisteningearsandmanyprayers.TomyCoworkers,thanksforlistening,support,kindwords,andsacricingsoIcouldgotoclass.Tomycommitteemembers,thankyouforyourhelpanddirection.

PAGE 3

TABLEOFCONTENTSLISTOFTABLESiiiABSTRACTivCHAPTER1INTRODUCTION11.1PurposeoftheStudy21.2ResearchQuestions2CHAPTER2HISTORY32.1Transmission42.2Epidemiology42.2.1Seasonality42.2.2Age42.2.3GeographicDistribution42.3UnderlyingMedicalConditions52.4ClinicalFeatures62.4.1Abscesses62.4.2Bacteremia72.4.3Endocarditis72.4.4Osteomyelitis82.4.5Pneumonia82.4.6ToxicShockSyndrome82.4.7StaphylococcalScaldedSkinSyndrome92.5Microbiology92.6AntibioticResistance102.7PathogenicMechanisms112.7.1Enzymes112.7.2Toxins122.8ImmunologicResponse132.9Treatment132.10Prevention14CHAPTER3LITERATUREREVIEW153.1PreviousStudies16i

PAGE 4

CHAPTER4METHODS284.1StudyDesign284.2InstitutionalReviewBoard284.3StudyPopulation294.4InclusionCriteria294.5ExclusionCriteria294.6SourcesofData304.7DataCollection304.8DenitionsandClassicationofVariables304.9StatisticalAnalysis32CHAPTER5RESULTS345.1DemographicCharacteristics345.2RiskFactorsforMethicillin-ResistantStaphylococcusaureus365.3MedicalConditions375.4TotalRiskFactors385.5EectModication385.6Confounding42CHAPTER6DISCUSSION436.1Findings436.2Strengths&WeaknessesoftheStudy466.3FutureDirections48REFERENCES51ii

PAGE 5

LISTOFTABLESTable1.Characteristicsofstudyparticipantsage18oryoungerseenatAllChildren'sHospital1/1/02-8/20/03intotalandbymethicillinstatus.35Table2.OddsRatiosandCondenceIntervalsforRiskFactorsforMRSAinfectionsinchildrenage0-18yearsatAllChildren'sHospital1/1/02-8/20/03.36Table3.Characteristicsofblackstudyparticipantsage18oryoungerseenatAllChildren'sHospital1/1/02-8/20/03intotalandbymethicillinstatus.39Table4.Characteristicsofwhitestudyparticipantsage18oryoungerseenatAllChildren'sHospital1/1/02-8/20/03intotalandbymethicillinstatus.40Table5.OddsRatiosand95%CondenceIntervalsforSubgroupAnalysisofBlackandWhiteofChildrenages0-18yearsfromAllChildren'sHospital1/1/02-8/20/0341Table6.AdjustmentofConfoundingforBlackandWhiteofChildrenages0-18yearsfromAllChildren'sHospital1/1/02-8/20/0342iii

PAGE 6

RiskFactorsforPediatricCommunity-AcquiredMethicillin-ResistantStaphylococcusaureusMelissaGailKesslerABSTRACTMethicillin-ResistantStaphylococcusaureusMRSAbeganasanosocomialinfec-tionduetooveruseofantibiotics.Severalpreviousstudieshavereportedanincreaseinthisinfectioninadultpatientswhohavenotbeenhospitalized.IthasalsobeenreportedthatthereisanincreaseinMRSAinchildren.Someofthesechildrenbe-cameinfectedeventhoughtheywerenotathighriskfortheinfection.AfterapprovalfromtheAllChildren'sHospitalInstitutionalReviewBoardIRB,acrosssectionalstudywasconductedwithpediatricadmissionsandpediatricemergencyroomvisitstodeterminethecharacteristicsofMethicillin-SensitiveStaphylococcusaureusandMRSA.Duringthisstudy,areviewof672medicalchartswasconducted.Thestudyparticipantsrangedinagefromnewbornsto18yearsofage.Inordertobeenrolledinthestudy,thesubjects'cultureswerecollectedeitherasoutpatientsorwithin72hoursofadmission.Thedatathatwascollectedfromeachchartincludedage,race/ethnicity,gender,typeofinfection,preexistingmedicalconditions,andriskfac-torsforinfection.Thepotentialriskfactorsincludeantibioticuse,previoussurgeryoroutpatientprocedure,previousMRSAinfection,immunotherapy,communityworndevice,andresidenceinafacility.StatisticalanalysiswasconductedusingEpiInfoandSASsoftwarepackages.Inregardstodemographiccharacteristics,blackchildrenare2.98timesmorelikelytohaveanMRSAinfectionthanwhitechildren.Genderandagewerenotriskfactorsforthedevelopmentoftheinfection.TheriskfactorsthatweresignicantinwhiteswerehomehealthcareOR=6.12,CI=5.16,7.08,iv

PAGE 7

communityworndeviceOR=2.28,CI=1.67,2.89,previoushospitalizationOR=2.43,CI=1.95,2.91,previousMRSAinfectionOR=3.69,CI=2.90,4.48,andpre-vioussurgeryOR=2.02,CI=1.51,2.53.Inblacks,femalesweremorelikelytohaveMRSAOR=2.57,CI=1.73,3.41.Thisndingmaybeduetothesmallsamplesizeofblackchildreninthestudy.Oftheanalyzedriskfactors,homehealthcareOR=2.95,CI=1.11,4.79,communityworndeviceOR=2.85,CI=1.71,4.01,previoushospitalizationOR=1.98,CI=1.13,2.83,previoussurgeryOR=2.79,CI=1.79,3.79,andpreviousantibioticOR=5.60,CI=4.66,6.54usewereallsignicantriskfactorsinblacks.Eectmodicationwastestedbetweenraceandallriskfactors.Racewasaneectmodieronlyfortheriskfactorofpreviousantibioticusepvalue=.02.Adjustmentofconfoundingwasperformedforeachraceduetothepresenceofeectmodication.Aftertheadjustmentforconfoundinginwhites,onlyhomehealthcareOR=4.37CI=1.55,12.32,previousMRSAinfectionOR=2.86CI=1.16,7.05,andprevioushospitalizationOR=2.00CI=1.14,3.50remainedstatisti-callysignicant.Inblacks,afteradjustmentofconfounding,onlypreviousantibioticuseOR=5.13CI=1.75,15.08remainedsignicant.Adjustmentforconfoundingwasalsopreformedonthetotalriskfactorsmodel.Adoseresponserelationshipwaspresentwithincreasingriskfactorspresent.v

PAGE 8

CHAPTER1INTRODUCTIONInthepasttwentyyears,therehasbeenanincreasingnumberofcasesofCommunity-AcquiredMethicillin-ResistantStaphylococcusaureusCA-MRSA.Manystudieshavebeenconductedontheadultpopulationbutverylittleattentionhasbeenpaidtothepediatricpopulation.Ofthestudiesthathavebeenconducted,manyfoundastartlingincreaseinCA-MRSAinchildren.HeroldetalconductedastudycomparingtheprevalenceofpediatricCA-MRSAinAugust1988-July1990toAugust1993-July1995atTheUniversityofChicagoChildren'sHospital.[1]Thestudyconcludedthattheprevalencehadrisenfrom10per100,000in1998-1990to259per100,000in1993-1995.[1]ThepredisposingriskfactorsforCA-MRSAnotedinthisstudywereprolongedhospitalization,invasiveorsurgicalprocedures,indwellingcatheters,en-dotrachealtubes,andprolongedorrecurrentexposuretoantibiotics.[1]SattleretalalsoconductedacomparisonofriskfactorsandclinicalcharacteristicsofCA-MRSAinchildrenandfoundthathospitalizationofhouseholdcontactsincreasedtheriskofMRSAinfection.[2]Anotherriskfactorthathasbeenreportedintheliteratureistheassociationbetweenparentsandhouseholdcontactsworkinginthehealthcareeldandtheseinfections.[2]IthasalsobeennotedthatCA-MRSAinfectionsaremorelikelytobesupercialskininfectionsthennosocomialMRSAinfections.[1,2,3]CA-MRSAcanalsobemoreeasilytreatedbecauseoftheirlackofresistancetonon-beta-lactamantibioticswhencomparedtonosicomiallyacquiredisolates.[1]1

PAGE 9

1.1PurposeoftheStudyThisstudywasinitiatedasaresultoftheconcernsexpressedbythestaatAllChildren'sHospitaltoRogerSanderson,RegionalEpidemiologistfortheFloridaDe-partmentofHealth,aboutapossibleincreaseinCA-MRSAattheirinstitution.ThepurposeofthisstudyistoexaminethecasesofMRSAoveraperiodofoneandahalfyears,2002-2003toperformepidemiologicanalysisofchildrenwithStaphylococ-cusaureusinfections.Theriskfactorsforinfectionwillalsobecollectedinordertodeterminetypeofpatientmostlikelytobecomeinfected.TheinformationfromthisstudywillbeutilizedtobetterassesspatientsuponentrytothehospitalastotheirriskofharboringMRSA.ThiswillalsohelpthehospitalpreventthespreadofMRSAtootherpatients.1.2ResearchQuestions1.DetermineiftheriskfactorsforMRSAintheadultpopulation,identiedinpreviousstudies,alsoapplytothepediatricpopulation.2.DeterminewhichriskfactorsaremorelikelytopredisposechildrentoMethicillin-ResistantStaphylococcusaureusinfection.3.ComparethedemographiccharacteristicsofchildrenwithMRSAtochildrenwithMethicillin-SensitiveStaphylococcusaureus.2

PAGE 10

CHAPTER2HISTORYInfectionfromStaphylococcusaureuswasaseriouscauseofmortalitybeforethead-ventofpenicillin.ItwasrecordedintheIliadbyHomerthat75%ofwoundedsoldiersdiedfollowingtheirinjuriesandthemostlikelycausewasinfection.[4]Itwasalsorecordedthat90-100%ofamputationsfrom1870-1871resultedindeathduringtheFranco-Prussianwar.[4]DuringtheSurgicalCongress,inBerlinonApril9,1880,AlexanderOgstondeliveredalectureonabscessesinwhichStaphylococcusaureuswasrstdescribedandillustrated.[4]HenamedthemStaphylococcusbecausetheirappearanceinclusterslookedlikeabunchofgrapes.[4]StaphylemeansbunchofgrapesinGreek.StaphylococcusaureusisagrampositivecocciintheMicrococcifamilyandmeasures0.5-1.5micronsindiameter.[5]InOgston'slecturehestatedthatherecoveredthesecoccifromnearly100%ofsamplesfromacuteabscessesfromvaryingpartsofthebody.[4]Aftertheintroductionofpenicillin,mortalityduetoStaphylococcusaureusin-fectionsdramaticallydecreased.[4]However,resistancetopenicillinsoonbegantodevelop.[4]Methicillinwasthenintroducedtotreatinfectionscausedbypenicillinresistantstrains.[4]Then,in1961,therstreportsinBritianofmethicillinresis-tantstrainsbegantosurfaceandsoonafter,severalcountrieswerereportingsimilarndings.[4,6]In1980only20%ofStaphylococcusaureusstrainsweresusceptibletopenicillin.NowMethicillin-ResistantStaphylococcusaureusMRSAisaglobalprobleminhospitals.[4]3

PAGE 11

2.1TransmissionMRSAinfectionsmaybeacquiredinseveraldierentways.Themostcommonwayistobecolonizedbythesestrains.[7]Health-careworkersarethemostfrequentsourceofexposureforpatients.[7]Thehealth-careworkers'handsfrequentlybe-cometransientlycolonizedwiththebacteriafromtheirownsourcesorthroughotherinfectedpatients.[7]Patientsmayalsobecomecolonizedorinfectedthroughothervarioussourcessuchasstethoscopes,bedding,bedrails,bedsidetables,andotherenvironmentalsources.[8]2.2Epidemiology2.2.1SeasonalityTherateofStaphylococcusaureusinfectionsisconstantthroughouttheyear,thereforeStaphylococcusaureusdoesnotshowanyseasonaltrend.[4]2.2.2AgeThosemostsusceptibletoinfectionscausedbyStaphylococcusaureusarethosewithweakerimmunesystems.[5]Withregardtoage,thetwopopulationswiththeweakestimmunesystemsaretheveryyoungandtheelderly.[5]Neonatalinfectionusuallyoccurintherstseveralweeksafterbirth.[5]Intheelderly,theinfectionsareas-sociatedwithincreasedexposuretovarioushealth-caresettingsincludinglong-termnursinghomefacilities.[5]2.2.3GeographicDistributionStaphylococcusaureusinfectionsarefoundworldwide.[4]Incidenceofinfectionishigherinareasassociatedwithpovertywhereovercrowdingiscommonandrunning4

PAGE 12

waterisscarce.[4]ClustersofinfectionshavebeendocumentedinaboriginalsinCanada,NewZealand,andAustralia.[4]AstudywasconductedbetweenJanuary1997andDecember1999wherebloodstreamisolateswererecordedinvariousareasoftheworldincludingtheUS,Canada,LatinAmerica,Europe,andtheWesternPacic.[9]ThisstudyfoundthatStaphylococcusaureuswasfoundtobethemostprevalentcauseofinfectioninallgeographicregions.[9]TheratesofMRSAinbothcommunityandnosocomialisolatesaresteadilyincreasing.[9]IntheUSbetween30-40%ofStaphylococcusaureusisolateswereMRSAandtherateofMRSAinEuropeancountriesisabout25%.[9]ThehighestrateswerefoundintheAsia-PacicregionwhichincludedTaiwan,Singapore,Japan,andHongKong.[9]TherateofMRSAinthisregionwasgreaterthan60%.[9]2.3UnderlyingMedicalConditionsSeveralunderlyingmedicalconditionsincreaseaperson'slikelihoodofbecomingin-fectedwithMRSA.ThemostimportantriskfactorforbecominginfectedwithMRSAistobecolonized.[10]Ofhealthyadults,30-50%arecolonized,with10-20%persis-tentlycolonized.[7]PatientswithtypeIdiabetes,patientsundergoinghemodialysis,surgicalpatients,burnpatients,andpatientswithHIV/AIDSareallatincreasedriskforinfection.[10]Patientswithqualitativeorquantitativedefectsinwhitebloodcellssuchascancerandleukemiapatientsandtransplantpatientsarealsoatrisk.[7]Pa-tientswithchronicskinconditionsandintravenousdrugusersarealsoatanincreasedrisk.[7,11]ThiswasrstdescribedinaCommunity-AcquiredMethicillin-ResistantStaphylococcusaureusCA-MRSAoutbreakinaDetroithospital.[11]Itishypoth-esizedthattheincreasedriskinduetotheuseofcommunalneedlesandsharingof5

PAGE 13

otherdrugparaphernalia.[11]Intravenousdrugusersalsotendtohavepoorhygienewhichincreasestheirlikelihoodtobecolonizedbythebacteria.[11]2.4ClinicalFeaturesInfectionscausedbyStaphylococcusaureuscaneitherbelocalizedorsystemic.Thisdependsonthedegreeofinvasionandtoxinproductionofthebacteria.Localizedinfectionsarecommonlyknownasabscesses.Systemicinfectionsmayincludebutarenotlimitedtobacteremia,endocarditis,osteomyelitis,andpneumonia.Therearealsotwotoxigenicstaphylococcaldiseases:toxicshocksyndromeandStaphylococcalscaldedskinsyndrome.2.4.1AbscessesStaphylococcusmayinvadetheskininseveralwaysincludingwounds,follicles,orskinglands.[5]Themostcommontypeofinfectionisfolliculitisandhidradenitis.[5]Theseinfectionsareamild,supercialinammationofhairfolliclesorglands.[5]Theseinfectionsareusuallyselflimitingbutmayprogresstosubcutaneoustissueinfections.[5]Furunclesorboilsareaprogressionoffolliculitisorhidradenitistoalargeredtenderpustule.[5]Theseoftenoccurinclusters,infrictionbearingareasofthebodysuchasbuttocks,breasts,axillae,andbackoftheneck.[5]Carbunclesareanaggregationofaclusteroffuruncles.[5]Theseinfectionsaremuchlargerandmorepainful.[5]Theyusuallyappearonareasofthickerskinsuchasthebackoftheneck.[5]Thisinfectionmayprogresstosystemicdisease.[5]Anothertypeofstaphylococcalskininfectionisimpetigo.[5]Thisinfectionischaracterizedbybubble-likeepidermalswellingsandmaybreakandpeelaway.[5]6

PAGE 14

2.4.2BacteremiaBacteremiaisdenedasthepresenceofviablebacteriainthebloodstream.[7]ThebacteriagainentrytothebloodstreamfromanytypeofStaphylococcalinfectioninwhichthebody'simmunesystemcannotcontain.[7]ThemortalityofStaphylococcalbacteremiahasremainedbetween11-43%overthepast15years.[7]Factorsassociatedwithincreasedmortalityduetobacteremiaareover50yearsofage,non-removablefociofinfection,andseriousunderlyingcardiac,neurologic,orrespiratorydisease.[7]Complicationsfrombacteremiafrequentlyoccursandtheratemaybeanywherefrom11-53%.[7]BacteremiacausedbyMRSAdoesnothaveanincreaseinmortalitywhencomparedwithMethicillin-SensitiveStaphylococcusaureus.[7]2.4.3EndocarditisEndocarditisistheinammationofthevalvesandliningoftheheart.[7]Thein-cidenceofendocarditiscausedbyStaphylococcusaureushasincreasedfrom1981to1988andmayaccountfor25-35%ofallendocarditiscases.[7]SomeriskfactorsforStaphylococcalendocarditisarebeinganintravenousdruguser,elderlypatients,patientswithprostheticvalves,andhospitalizedpatients.[7]Staphylococcusaureusendocarditisdiersinpresentationfromotherendocarditisbyitsrapidonset,highfever,andfrequentinvolvementofnormalcardiacvalves.[7]Inintravenousdruguserswhodevelopendocarditis,thediseaseismostoftenfoundontherightsideoftheheart.[7]ThepatientsalsotendtobeyoungerandhavealowermortalityrateifnotalsoinfectedwithHIV.[7]Inendocarditis,notrelatedtodruguse,thediseaseismoreoftenfoundintheleftsideoftheheartandhasahighmortalityrate.[7]Thediseaseusuallyinvolvespreviouslydamagedvalves.[7]Staphylococcusaureusisoneofthemostcommonpathogensinnosocomialandprostheticvalveendocardi-7

PAGE 15

tis.[7]Intravenouscathetersarethemostfrequentsourceofbacterialinoculation.[7]Themortalityratefornosocomialendocarditisregardlessofpathogenis40-56%.[7]TheratemaybeevenhigherwhentheonlypathogentakenintoconsiderationisStaphylococcusaureus.[7]2.4.4OsteomyelitisOsteomyelitisisaninfectionofthevascularmetaphysisofbones.[5]Thebonesthataremostcommonlyinvolvedarethefemur,tibia,ankle,orwrist.[5]Necrosisofbonytissueandabscessformationleadtoanelevatedandtenderlump.Osteomyelitisoccursintwoforms,primaryandsecondary.[5]Primaryosteomyelitisistypicallyseeningrowingchildren,adolescents,andintravenousdrugusers.[5]Secondaryortraumaticosteomyelitistypicallydevelopsafteracompoundfractureorsurgeryincancerordiabetespatients.[5]2.4.5PneumoniaStaphylococcusaureuscanbeaspiratedintothelungsandcausepneumoniabecausethebacteriafrequentlycolonizingthenasopharynx.[5]Thefatalityrateis50%eventhoughStaphylococcusaureusaccountsforonlyaverysmallproportionofpneumoniacases.[5]2.4.6ToxicShockSyndromeToxicShockSyndromecameintoprominencein1980-1981,whennumerouscaseswereassociatedwithinintroductionofsuperabsorbenttampons.[7]Thediseasehadafulminantonsetandwasoftenseeninpreviouslyhealthyfemales.[7]ToxicShockSyndromedoesnotdevelopfromasiteofcolonizationandisnotalwaysasso-ciatedwithmenstruation.[7]Infact,athirdofallcasesarenon-menstrual.[7]The8

PAGE 16

non-menstrualcasesareassociatedwithlocalizedinfectionsfromsurgeryorinsectbites.[7]ToxicShockSyndrometoxinIispresentin90%ofToxicShockSyndromemenstrualcases,howeverotherToxicShockSyndrometoxinshavebeenassociatedwithnonmenstrualcases.[7]PatientwithnonmenstrualToxicShockSyndromehaveahighermortalityratethanthoseassociatedwithmenstruation.[7]2.4.7StaphylococcalScaldedSkinSyndromeStaphylococcalScaldedSkinSyndromeiscommonlyseenischildrenwithinfectionsoftheumbilicalstumporeyes.[5]Theseinfectionsleadtotoxemiaandwhenthetoxinreachestheskinitinducesapainfulbrightredushovertheentirebody.[5]Theskinthenblistersfollowedbydesquamationoftheepidermis.[5]Themajorityofcaseshavebeendescribedininfantsandchildrenunderagefour.[5]Exfoliativetoxinisthetoxinthatisresponsibleforthisinfection.[5]ThistoxinalsocausesStaphylococcalimpetigowhichcanaectallages.[5]2.5MicrobiologyStaphylococcicanbeisolatedfrompus,tissueexudates,sputum,urine,andblood.[5]Thesespecimensaretheninoculatedontosheeporrabbitbloodagar.[5]ThecoloniesthatgrowifStaphylococcusaureusispresentinthespecimenarelarge,round,andopaque.[5]Thebacteriagrowsbestat37degreesCelsiusandisafacultativeanaer-obe.[5]Thismeansthebacteria'sgrowthisenhancedinthepresenceofoxygenandcarbondioxide.[5]Thebacteriacanwithstandhighsaltcontents,extremesinpH,andhightemperatures.[5]Itcanalsoremainviableaftermonthsofairdryinginad-ditiontobeingresistanttomanydisinfectants.[5]Thesecharacteristicshaveallowed9

PAGE 17

theorganismtocontinuetoplaguethehealth-caresystemdespiteimprovementinbothpublichealthandhealth-care.WhenagramstainisperformedonStaphylococcusaureuscoloniesitstainsgrampositiveandmaybeobservedinirregularclusters.[5]GramstainaloneisnotenoughtoconrmthepresenceofStaphylococcusaureus.[5]ThebacteriawillbetestedforthepresenceofcatalasewhichdierentiatesitfromStreptococciwhichlacktheenzyme.[5]StaphylococciaredierentiatedfromMicrococcibytheirabilitytogrowanaerobicallyandtofermentsugars.[5]AfterthegenusStaphylococcushasbeenconrmed,acoagulasetestisperformed.[5]StaphylococcusaureusistheonlyspeciesofStaphylococcitoproducecoagulase,therefore,thepresenceoftheenzymeconrmsapositivecultureforStaphylococcusaureus.[5]2.6AntibioticResistanceShortlyaftertheintroductionofpenicillin,resistantstrainstotheantibioticwerenoted.Despitethepresenceoftheantibiotic,thebacteriacontinuedtogrow.Thebacteriahadadaptedtoitsnewtreatmentbyproducinglactamaseorpenicillinase.Thisenzymeinactivatesthepenicillinbyhydrolyzingthe-lactamringinitsstruc-ture.[7]Thisenzymeisinducibleandisoftencodedforinplasmids.[7]Today,lessthan5%ofStaphylococcusaureusisolatesaresensitivetopenicillin.[7]Otherantibiotics,suchasmethicillin,werecreatedtoovercomethepresenceof-lactamase.[7]Aftertheintroductionofmethicillinandothersimilarantibi-otics,resistancewasalsonoted.Resistancetomethicillinconfersresistancetoallpenicillinase-resistantpenicillinsandcephalosporins.[7]Thisresistancerequiresthemecgenewhichencodesforpenicillin-bindingprotein2a.[7]Penicillin-bindingpro-teinsaremembraneboundenzymesthatbecomealteredwiththepresenceofthemec10

PAGE 18

gene.[7]Thepenicillin-bindingproteinsarethetargetsofthe-lactamantibiotics.[7]Withoutthemecgenetheseantibioticshaveahighanityforthepenicillin-bindingproteins.[7]Withtheintroductionofthemecgenethebacteriaproducesmodiedpenicillin-bindingproteinswhichhavealoweranityfortheantibiotic.[7]2.7PathogenicMechanismsStaphylococcusaureusisacommonorganismthatcanbefoundaspartofaperson'snormalora.[7]Itcancolonizevariousareasofthebodyincludingthenares,axillae,vagina,pharynx,anddamagedskin.[7]Staphylococcusaureuscanremaincolonizedonapersonindenitelywithoutcausinganyproblems.[7]Onlywhentheorganismisintroducedintosurroundingtissuesorthebloodstreamthroughabreakintheskinormucousmembrane,mayaproblemarise.[7]Theinfectionmayremaincontainedinoneareaordisseminatedependingontheindividualsdefensemechanisms.[7]Thepresenceofintravenousdevicesandurinarycathetersincreasestheriskofinfection.[7]ThepathogenicityofStaphylococcusaureusiscausedbyseveralenzymesandtox-ins.Theprincipleenzymesthataredocumentedarecatalase,coagulase,hyaluronidase,and-lactamase.Theprincipletoxinsarehemolysins,exotoxins,andexfoliativetoxin.2.7.1EnzymesCatalase:AllStaphylococcispeciesproducecatalase.[5]Thisenzymesbreaksdownhydrogenperoxideintowaterandoxygen.[5]Hydrogenperoxideisusedbyneu-trophilsduringphagocytosis.[5]Theneutrophilsuseshydrogenperoxidetoformtoxicoxygenradicals.[5]Thepresenceofcatalasecounteractsthismechanism.[5]11

PAGE 19

Coagulase:OnlyStaphylococcusaureusspeciesproducecoagulase.[5]Thisenzymecoagulatesplasmaandbloodandcausesbrintosurroundthebacteriaandprotectitfromthehostdefenses.[5]Theenzymealsopromotesadherencetotissues.[5]Hyaluronidase:Thisenzymeisalsoknownasthespreadingfactor.[5]Itdigeststheintracellularglueorhyaluronicacidthatbindstheconnectivetissueinthehost.[5]-Lactamase:Thisextracellularenzymeopensthe-lactamringofpenicillinbasedantibiotics.[5]2.7.2ToxinsHemolysins:Thisgroupoftoxinscausesthelysisofredbloodcells.[5]Therearefourdierenttypesofthistoxin,,,and.[5]-toxinisthestrongesthemolysin.[5]Aswellaslysingredbloodcellsitalsodamagesleukocytes,andskeletalmuscle,andheartandrenaltissue.[5]-toxindegradessphnogomyelinandeectsredbloodcells,leukocytes,andbroblasts.[5]-toxinlysesredbloodcellsbutthemechanismisunknown.-toxinactsasadetergentdisruptingbiologicmembranes.[5]Exotoxins:Thetwomostimportantexotoxinsareleukocidinandenterotoxin.[5]Leukocidindamagesthecellmembraneofmacrophagesandneutrophilsandisanotherwaytoinhibitthephagocytichostdefense.[5]Enterotoxinsactonthegastrointestinaltractofhumanstoproducediarrhea.[5]ExfoliativeToxin:Thistoxinseparatestheepidermallayeroftheskinfromthedermiscausingittopeelaway.[5]ItisresponsibleforStaphylococcalScaldedSkinSyndrome,inwhichtheskinappearsburned.[5]12

PAGE 20

2.8ImmunologicResponseStaphylococcusaureusinvadesthehostbyabreakintheskinormucousmem-brane.[7]Onceinvasiontakesplacethehostrespondsbyactivatingtheneutrophilsandmacrophages.[7]Thecomplementsystemalsoplaysaroleinthehostdefenses.[7]ThereareseveralcomponentsinthecellwallofStaphylococcusaureusthatactivatethecomplementsystem.[7]Oneofthesecomponentsispeptidoglycanwhichacti-vatesthealternativecomplementpathwaywhichresultsinthereleaseofC3aandC5a,aswellasactivationofneutrophils,macrophages,andnaturalkillercells.[7]Afterthebacteriaiscoatedwithcomplement,themacrophagesattaches.[7]Duringphagocytosis,thebacteriaisexposedtooxygenradicals.[7]ThisleadstoadecreaseinpHandthenthelysosomalenzymesbecomeeective.[7]This,alongwithlactofer-rin,areanothermeansoftheintracellularmechanism.[7]Humoralandcellmediatedresponsesarelaunchedinadditiontointracellularkilling.[7]2.9TreatmentAbscessesmustbesurgicallyperforatedandclearedofpusandforeignbodies.[7]Severesystemicinfectionsrespondslowlyandrequireintensiveandlengthyoralorinjectedtherapy.[7]Penicillinisstillthedrugofchoiceiftheisolateissensi-tive.[7]Semi-syntheticpenicillinsarepreferredif-lactamaseproductionisdemon-strated.[7]Ifthepatienthasanallergytopenicillin,cephalosporinsareused.[7]IfMRSAisrecoveredvancomycin,uoroquinolones,trimethoprim-sulphamethoxazole,clindomycin,orminocyclinemaybeutilized.[7]Thereareseveralotherantimicrobialcombinationsthatmaybeutilizedtoincreasebacteriocidalactivityorpreventthedevelopmentofresistance.[7]Therapyforinvasive,lifethreateninginfectionsisfour13

PAGE 21

weeksorlonger.[7]Iftheinfectionisoriginatingfromanindwellingdevice,removalissuggestedwhenpossible.[7]2.10PreventionItisimpossibletopreventallcolonizationsandinfectionsaslongashumansarethebacteria'sprimaryreservoir.Thebestwaytopreventthespreadofanybacteriaishandwashing.[12]Healthcareworkersandfamilymembersneedtobeeducatedontheproperhandwashingtechniques.[12]APICguidelinesspecifythathandsshouldwashedforatleast10secondsbeforeleavingapatient'sroomregardlessifglovesarewornornot.[13]SHEAguidelinesalsoindicatethatwhenthereisnovisiblecontaminationofgloveswithbloodorbodyuidsthatalcoholbasedhandrubswithemollientmaybeused.[14]ContactprecautionsshouldbepracticedonallcasesofMRSA.[12]Patientsoncontactprecautionsshouldhaveaprivateroom.[12]Contactprecautionguidelinesspecifythatyoushouldwearglovesandgownsuponeachentrytothepatient'sroomforalldirectpatientcare.[12]SHEAguidelinessuggesthowever,thatglovesandgownsshouldbeworneveniftherewillonlybecontactwiththeenvironmentalsurfacesofaninfectedpatientsroom.[14]ThegownsshouldberemovedbeforeleavingthepatientsroominordertopreventthespreadofMRSAtootherpatients.[12]Patientcareequipmentshouldbededicatedtoasinglepatienttopreventthespreadofthebacteriaaswell.[12]Allhospitalpersonnelshouldhaveannualcontinuingeducationonpatientcareandbasicinfectioncontrolpractices.[12]Patientsshouldnotsharefoodordrinksandallpersonalitemsshouldbethoroughlydisinfectedbeforesharingwithotherpatientsorfamilymembers.[12]14

PAGE 22

CHAPTER3LITERATUREREVIEWMethicillin-ResistantStaphylococcusaureusMRSAwasrstisolatedin1961intheUnitedKingdom.[15]Thiswasoneyearaftermethicillinwasintroducedasatreat-mentforStaphylococcusaureus.[15]ThenMRSAslowlydisseminateduntilitbegancausingserioushospitalinfectionsinthe1970's.[15]MRSAhasbecomeincreasinglyprevalentinnursinghomes,rehabilitationfacilities,andnoweveninthecommu-nity.[15]MethicillinresistanceisconferredbytheSCCmecgene.[15]Therearefourgeneticclassesofthemecgene.[15]ItishypothesizedthattypeISCCmecwaspresentintherststrainsofMRSAthatwereisolatedinthe1960's.[15]TypeISCCmecdoesnotcontainanyotherantibioticresistancegenes.[15]TypeIIandtypeIIISCCmeccontainmultipleresistancegenes.[15]Thesetypesbecameprominentinthe1980'sinnosocomialisolates.TypeIVSCCmeciscommonlyisolatedfromcommunityacquiredcases.[15]Thistypeonlyencodesformethicillinresistance.[15]Itissusceptibletomanyothernon--lactamantibiotics.[15]TypeIVSCCmechasbeenisolatedfrommanycountriesincludingJapan,France,andAustraliawhichdemonstratestheinternationaldisseminationoftypeIVSCCmec.[15]ThemajorityofliteraturediscussesriskfactorsfortheacquisitionofMRSA.Someofthemostcommonriskfactorsareprevioushospitalization,especiallyinintensivecareunitsorburnunits,precedingantimicrobialtherapy,andsurgicalprocedures.[16,17,18,19,1,3,20,21]Somestudieshavealsonotedintravenousdruguseandnursing15

PAGE 23

homeresidenceasriskfactors.[16,17,18,19]Inthepediatricpopulation,daycareattendanceandhavingafamilymemberhospitalizedwithinthepastsixmonthsarenotedaspotentialriskfactors.[2,22,19,1,3,20]3.1PreviousStudiesTherehavebeenseveraloutbreaksofCommunity-AcquiredMethicillin-ResistantStaphy-lococcusaureusCA-MRSAnotedintheUnitedStates.Therstofthesewasre-portedbyRathoreandKlinein1989.[23]ThereweretwocasesofseriousMRSAinfectionsinchildrenwholackedanypriorhistoryofseriousmedicalorsurgicalill-ness,antibiotictherapy,orhospitalization.[23]Therstcasewasaneightyearoldboywithosteomyelitisoftheleftcalcaneus.[23]Thesecondcasewasatenmontholdgirlwithbacteremia.[23]Bothchildrenhadparentsthatwerehealthyanddeniedintravenousdruguseorcontactwithofanyfamilymemberwithhealth-careworkersorhealth-carefacilities.[23]TheCentersforDiseaseControlandPreventionhasalsoreleasedseveralreportsofCA-MRSA.TherewerefourpediatricdeathsinMinnesotaandNorthDakota.[24]Therstcasewasasevenyearoldgirlwithaninfectedrighthipjoint.MRSAwasisolatedfromtheblood,hipjoint,andsputum.[24]Thegirlhadnorecenthospital-izationsandnofamilymemberswithanycontactwithnursinghomesorhealth-caresettings.[24]Thesecondcasewasasixteenmontholdgirlwithapriorotitismediainfection.[24]Theorganismwasisolatedfromherbloodandspinaluid.[24]Shealsohadnopredisposingriskfactors.[24]Thethirdcasewasathirteenyearoldgirlwithnopredisposingrisk.[24]MRSAwasisolatedfromherblood,sputum,andpleuraluid.[24]ThelastcasewasatwelvemontholdboywhosesisterwastreatedforanMRSAabscess.Theorganismwasrecoveredfromtheboy'spleuraluidandpost16

PAGE 24

mortemblood.[24]Theisolatesofthebrotherandsisterwereidentical.[24]AlloftheMRSAisolatesinthesefourcasessusceptibletoallantimicrobialagentsexcept-lactams.[24]TherewerealsothreecommunityoutbreaksofskininfectionsassociatedwithMRSAinLosAngelesCountyin2002.[25]Therstoutbreakwasfromtwoathletesonthesamewrestlingteam.[25]ThesecondoutbreakwasreportedbytwolargeinfectiousdiseaseclinicalpracticeswhohadanincreaseinMRSAinhomosexualmen.[25]ThelastoutbreakwasreportedbytheLosAngelesCountyjail.[25]Eachoftheseoutbreakshadsimilarantimicrobialsusceptibilitypatternsandwereallthesamepredominantstrain.[25]ThelastreportedoutbreakofMRSAinthecommunitywasfood-borne.[26]Thisoutbreakwaslinkedtoafoodhandler,foodspecimens,andthreeillpatrons.[26]ThiswastherstreportofanoutbreakofgastrointestinalillnesscausedbyCA-MRSA.[26]Therehavebeentwoprevalencestudiesconductedonadultsconcerningcommu-nitycolonizationbyMRSA.BothofthesestudieswereperformedintheUnitedKingdom.TherstwasconductedbyAbuduetalusingarandomsampleofadultsresidinginBirmingham,UKin1998.[27]ThesamplewasrandomlyselectedfromthesurveypracticeslistontheHealthAuthoritypopulationregisterusingrandomnumbersequences.[27]Theparticipantshadtobeovertheageofsixteenandnurs-inghomeresidentswereexcluded.[27]Swabsoftheanteriornaresweretaken.[27]Commoncultureandantimicrobialsusceptibilitytestingpracticeswereutilized.[27]Theparticipantsalsocompletedaquestionnairewhichassessedinformationaboutriskfactorsfortheacquisitionoftheorganism.[27]Theresponseratewas58%.[27]Femalescomprised60%ofthesampleandminor-ityethnicgroupsmadeup8%ofthesample.[27]Staphylococcusaureuswasobtained17

PAGE 25

from63isolates,whichisaprevalenceof23%.[27]MRSAwasisolatedfrom4ofthe63isolateswhichisaprevalenceof1.5%.[27]Nosignicantdierencewasfoundbe-tweenanyoftheparticipantsfromwhichStaphylococcusaureuswasisolated.[27]AlloftheMRSAisolatesthatwererecoveredwereconsistentwiththeprevalentstraininBirminghamhospitals.[27]Thissuggeststhattheseisolatesweremorelikelytobeassociatedwithcarriageofhospital-acquiredstrainsinthecommunityratherthantransmissionwithinthecommunity.[27]Thisstudyhadseverallimitationsresultingfromsamplingbias.[27]Thiswasduetoapoorresponserate,smallsamplesize,andahigherproportionofsubjectsoversixtyvethaninthegeneralpopulation.[27]ThesecondprevalencestudythatwaspreformedintheUnitedKingdomwasbyGrundmannetalwhoinvestigatedtheprevalenceofnasalcarriageofMRSAinasampleofpeopleagedsixtyveandover.[28]TheseparticipantsallresidedintheirownhomesinthegreaterNottinghamHealthDistrict.[28]Thesamplesizewas962.[28]Samplesweretakenfromtheanteriornaresanddemographiccharacteristicsandriskfactordatawasalsocollectedfromtheparticipants.[28]Staphylococcusaureuswasisolatedfrom257participants,eightwereMRSA.[28]Thepopulationprevalencewaseightperthousand.[28]MRSAwasassociatedwithhospitaladmissioninthepastsixmonthsanddiabetes.[28]ThepresenceofchronicskinulcerswasastronglyassociatedconfounderwithMRSAandprevioushospitaladmissions.[28]AllMRSAisolateswereindistinguishablefromthecloneofMRSAwasprevalentinEnglishhospitals.[28]TherewereseveralmedicalchartreviewsthatwerepreformedinvarioushospitalsonadultCA-MRSApatients.TherstchartreviewwaspreformedbyMorinandHadler.TheydidaretrospectivereviewofallpersonsadmittedwithStaphylococcusaureusbacteremiain1998,infourConnecticutmetropolitanareas.[29]Thepurposeofthisstudywastoanalyzethemagnitudeandepidemiologyofcommunity-onset18

PAGE 26

StaphylococcusaureusandMRSA.[29]Thefourmetropolitanareascomprisedforty-onetownswithatotalpopulationofoveronemillionandincludednineacute-carehospitals.[29]ThemedicalchartsofpatientswithStaphylococcusaureusbloodstreaminfectionsduring1998wereanalyzed.[29]Theinformationextractedfromthechartswasthetownofresidence,age,sex,race/ethnicity,dateofadmissionanddischarge,dateofculture,outcomeinfection,antibioticsusceptibility,hospitalizationhistory,iatrogenicriskfactorsforbacteremia,andunderlyingillnesses.[29]Thestudypop-ulationwasonehundredninetytwopatientswithcommunity-onsetbacteremia.[29]Theoverallincidenceofinfectionwas17/100,000.[29]Thehighestincidenceofinfec-tionwereamongmales,adultsoversixtyve,blacks,andresidentsofurbanareas.[29]MRSAwasfoundin15%ofinfectionswhichmadetheoverallincidenceofcommunity-onsetMRSAbacteremia2.5/100,000.[29]Healthcareassociatedinfectionsaccountedforthemajorityofbacteremia.[29]Ofallcommunity-onsetStaphylococcusaureus,only6%hadcommunity-onsetwithnounderlyingmedicalconditions.[29]Theoverallcase-fatalityrateforMRSAwas14%.[29]Themainlimitationofthestudywasthattheonlyinfectionunderconsiderationwasbacteremia.[29]Therewasalsonoinfor-mationonoutpatientantibioticuseandnomolecularmethodwasusedtocomparenosocomialtocommunitystrains.[29]SalmenlinnaetalconductedastudytoestimatetheproportionofCA-MRSA.[30]TheanalysiswasconductedonprevioushospitalizationsforallMRSApositiveper-sonsinFinlandfrom1997-1999.[30]AcomparisonofMRSAisolatesinpersonswithandwithouthospitalcontactintermsofstraintype,antibioticresistance,andmecdeterminantprole.[30]DatawasobtainedfromtheNationalHospitalDischargeRegister.[30]Therecordscontainedthedate,thespecimensource,patientdateofbirth,sex,andplaceoftreatment.[30]Phagetyping,pulseeldgelelectrophoresis,andantimicrobialdrugsusceptibilitywerealsorecorded.[30]Therewerevehundred19

PAGE 27

andtwentyMRSAisolatesinFinlandduringthatperiod.[30]Theannualincidencerangedfrom2.3/100,000-4.1/100,000andtheproportionofCA-MRSAisolateswas21%.[30]Threestraintypeswereidentiedthatwereassociatedwithcommunityacquisitionandnoneofthesestrainsweremulti-resistant.[30]ChildrenwerefoundtobemorelikelytohaveCA-MRSA.[30]ThelimitationsofthestudywerethatsomeMRSAcouldhavebeenisolatedfromnursinghomeresidents.[30]Thesecasesshouldhavebeenclassiedashealth-care-associated.[30]Also,localsamplepolicydierencesmayhaveaectedthenumberandtypeofCA-MRSAidentied.[30]SamplingandscreeningpoliciesinthecommunitysettingarenotspeciedinthenationalguidelinesforMRSApreventioninFinland.[30]Theseguidelinesareprimarilydirectedforuseinahospitalsettingwithnosocomialinfectionsastheirfocus.[30]Thirdly,noclinicalandriskfactordatawascollectedbesidesprevioushospitalization.[30]ThelastchartreviewofadultswasconductedbyJohnsonetal.[17]Theycon-ductedareviewofCA-MRSAcasesofbacteremiaandevaluatedtheriskfactorsandepidemiology.[17]ThiswasacasecontrolstudycomparingMRSAtoMethicillin-SensitiveStaphylococcusaureusbacteremiaata600bedurbanacademicmedicalcenter.[17]Thechartsoftheparticipantswerereviewedtocollectdataregardingun-derlyingconditions,sourcesofbacteremia,microbiology,patientoutcomes,previoushospitalizations,andantibioticsusceptibility.[17]Thecasesandcontrolsweresimi-larinallaspectsexceptthatthepatientswithMRSAbacteremiawasmorelikelytohavepresentedfromalong-termcarefacilityandtohavemultipleadmissionswithintheprecedingyear.[17]ThisstudyconcludedthatthemajorityofCA-MRSAbac-teremiawashealth-care-associatedandoccurredinpatientswithunderlyingmedicalconditions.[17]TambyahetalconductedastudyassessingthefrequencyofCA-MRSAinfectionsatateachinghospitalinSingapore.[18]Thestudywasprospectiveinnature,collect-20

PAGE 28

ingdataforMRSAisolatesfromJanuarytoDecember1998.[18]TheprevalenceofCommunity-AcquiredMethicillin-ResistantStaphylococcusaureuswas43%.[18]Themajorityofinfectionswereoftheskinandsofttissue.[18]OfalloftheCommunity-Acquiredinfections,allbutonecasehadbeenexposedtooutpatientcenters,visitingnurses,orcommunityhospitals.[18]TheantibioticresistancepatternsinCA-MRSAweresimilarwhencomparedwithnosocomialisolates.[18]ThisstudydemonstratedthatmanypresumedCA-MRSAinfectionsaretrulyhealth-careassociatedduetotheincreaseinhealth-careinoutpatientsettings.[18]Somestudieshavebeenconductedonthepediatricpopulation.Amongtheseareseveralchartreviews.ThemostwelldocumentedofthesewasconductedbyHeroldetal.ThepurposeofthisstudywastodeterminewhetherCA-MRSAinfectionsinchil-drenwithnopredisposingriskfactorswasincreasing.[1]ThestudyalsodenedthespectrumofdiseaseassociatedwithMRSAisolationwhencomparedtoMethicillin-SensitiveStaphylococcusaureusinfections.[1]ThestudydescribedtheepidemiologyofCA-MRSAamonghospitalizedchildreninfourways.[1]AcomparisonoftheprevalenceofCA-MRSAwithidentiedriskintwotimeperiods1988-1990and1993-1995.[1]Acomparisonoftheproportionsofinfectingversuscolonizingisolateswasconductedforthetwotimeperiods.[1]Athirdcomparisonoftheclinicalspectrumofdiseaseforinfectingisolatesin1993-1995.[1]Theinfectingisolatesweresplitintovecategories:CA-MRSAwithidentiedrisk,CA-MRSAwithoutidentiedrisk,nosoco-mialMRSA,Community-AcquiredMethicillin-SensitiveStaphylococcusaureus,andnosocomialMethicillin-SensitiveStaphylococcusaureus.[1]AfourthcomparisonofthethreeMRSAgroupssusceptibilitiestootherantibioticswasalsoconducted.[1]TheprevalenceofofCA-MRSAwithoutidentiedriskfactorsincreasedfrom10/100,000admissionsin1988-1990to250/100,000admissionsin1993-1995.[1]Clinicaldiseasewasassociatedwith43%ofCommunity-Acquiredisolatesfromchildrenwithiden-21

PAGE 29

tiedriskand37.5%ofnosocomialisolateswereassociatedwithclinicaldiseasein1988-1990.[1]Incontrast,in1993-1995,80%ofCommunity-Acquiredisolatesfromchildrenwithidentiedriskand88%ofCommunity-Acquiredisolatesfromchildrenwithoutidentiedrisk,and71%ofnosocomialisolateswereassociatedwithclinicaldisease.[1]Inaddition,comparingtheclinicalspectrumofdisease,thedistributionofclinicalsyndromesassociatedwithCA-MRSAinchildrenwithidentiedriskwassimilartothatofchildrenwithnosocomialacquireddisease.[1]TheclinicalspectrumofdiseaseforCA-MRSAwithoutidentiedriskwasverydierent.[1]BacteremiawasassociatedwithnosocomialandCA-MRSAwithidentiedrisk.[1]AbscessesaremorecommonlyseeninCA-MRSAwithoutidentiedrisk.[1]ThediseaseassociationrateforCommunity-AcquiredMethicillin-SensitiveStaphylococcusaureusissimilartoCA-MRSAaswellasthedistributionofclinicalsyndromes.[1]Withregardstoantibioticsusceptibility,isolatesfromchildrenwithCA-MRSAandnoidentiedriskweremorelikelytobesusceptibletootherantibioticswhencomparedtoCA-MRSAwithidentiedriskandnosocomialisolates.[1]AnotherpediatricchartreviewstudywasperformedbyGorak,Yamada,andBrown.Thisstudywasconductedfrom1992-1996usingpatientshospitalizedwithCA-MRSAinfectionsinHonolulu.[3]Thepurposewastoassessthepatientsriskfactors.[3]AllthemedicalrecordsofpatientsadmittedwithCA-MRSAwereana-lyzed.[3]Patientswereexcludediftheyhadaprevioushospitalizationwithinthepastsixmonths,transferredfromotherhospitals,orwereresidentsofnursinghomesorotherlong-termcarefacilities.[3]Therecordswerereviewedforresidencystatus,travelhistory,admittingservice,historyofalcohol,tobacco,andintravenousdruguse,familymemberorclosecontactwithpyoderma,previousantimicrobialtherapy,surgicalintervention,siteofculture,antimicrobialsusceptibilities,andunderlyingmedicalconditions.Ofclinicallyinfectedpatients,93%hadskinandsofttissue22

PAGE 30

infections.[3]Communityacquiredisolatesweresusceptibletoagreaternumberofantibiotics.[3]Thisstudywasuniquebecausethepatientpopulationinthesehospi-talswereprimarilyyoungandhealthymilitarymen.[3]FergieandPucellconductedaretrospectivestudytoreportthefrequencyofCA-MRSAisolates,describethespectrumofdiseaseofchildreninfectedwithCA-MRSAandcomparetheantibioticsusceptibilitypatternsofCommunity-Acquiredandnoso-comialMRSAinfections.[20]AllcasesofStaphylococcusaureuswereidentiedfromOctobertoDecember2000.[20]ThemedicalrecordswerereviewedforallchildrenwithCA-MRSAandthefollowinginformationwasrecordedfromthecharts:diag-nosis,siteofculture,antibioticsusceptibility,andpresenceofanyknownriskfac-tors.[20]Theseriskfactorswereunderlyingchronicdisease,residenceinalong-termcarefacility,daycareattendance,householdcontactwithidentiedriskfactors,re-centhospitalizationorsurgery,presenceofanindwellingcatheter,intravenousdruguse,andpreviousantibioticuse.[20]TheprevalenceofCA-MRSAwas47%with88%ofthesecaseshavingnoidentiedrisk.Softtissueinfectionsaccountedfor91%ofthesecases.[20]CA-MRSAaccountedfor12%oftheMRSAisolatedfrom1990-1996and59%from1997-2000peakingat80%in2000.[20]TheannualrateofMRSAisolationincreasedfrom2.9%ofallStaphylococcusaureusisolatesin1990to19.0%in2000.[20]CA-MRSAisolatesfromchildrenwithoutidentiedriskweremorelikelytobesusceptibletotrimethoprim-sulphamethoxazoleandclindomycin.[20]Nosoco-mialisolatesweremoresusceptibletotetracycline.[20]ThisstudyhasdemonstratedadramaticincreaseinCA-MRSAinchildrenwithnoknownpredisposingriskfac-tors.[20]AretrospectivecohortstudywasconductedbyCampbelletaltodescribetherelativecontributionofriskfactorsforbothCommunity-AcquiredandnosocomialMRSAinfections.[21]TheparticipantswereallchildrenwithMRSAinfections,at23

PAGE 31

atertiarycarechildren'shospitalbetweenOctober1999andSeptember2001.[21]Medicalrecordswereusedtocollectdataondemographics,dateandsiteofculture,diagnosis,initialandnalantibioticandsurgicaltherapy,andpreviousmedical,mi-crobiological,surgical,anddevicehistory.[21]Thesamplesizewas62.[21]PatientswithCA-MRSAtendedtobeolderwithamedianageof5.5yearsversus1.5years.[21]SignicantriskfactorsforCA-MRSAwereprevioussurgeryandantibioticsatpre-sentation.[21]Exposuretoendotrachealtubes,centralvascularcatheters,andchesttubeswerelesscommoninCA-MRSApatientsandresistancepatternsweresimi-larbetweenCommunity-Acquiredandnosocomialisolates.[21]Only8%ofpatientswithCA-MRSAhadnohealth-carerisk.[21]TheseresearchersconcludedthatthemajorityofCommunity-Acquiredcaseswereinrealitynosocomialcasesduetosim-ilarresistancepatternsandthepresenceofriskfactorsincludingcontactwiththehealth-careenvironment.[21]Thisriskfactoralonecouldhaveledtocolonizationwhichlaterprogressedtoinfection.[21]Thisobscuredthelikelihoodofnosocomialtransmissionanddelayedtheinvestigationofpooradherencewithinfectioncontrolpractices.[21]TherehavebeentwostudiesconductedwithchildrenatdaycarecentersfollowingthediagnosisofachildwithMethicillin-ResistantStaphylococcusaureus.ShahinetalconductedastudyoftheprevalenceofMRSAandMethicillin-SensitiveStaphylococcusaureuscolonizationinachildcarecenterinToronto.[31]TheindexcaseofCA-MRSAwasatwoandahalfyearoldchild.[31]Consentingparentscompletedaquestionnaireandpermittedscreeningoftheirchildrenfromthroat,nose,andperianalsitesandnasalandperianalswabswereobtainedfromthechildcentersta.[31]Therewasaresponserateof81.8%forchildrenand100%forsta.[31]PositiveStaphylococcusaureuscultureswererecoveredfrom24.4%ofchildren.[31]OnlyoneclassmateandthesiblingoftheindexcasehadpositiveMethicillin-ResistantStaphylococcusaureus24

PAGE 32

cultures.[31]Theclassmatehadadiagnosisofdermatitisthatprecededtheindexcaseforthisbythreemonthswhichraisesthepossibilitythattheindexcaseinthisstudymayactuallybeasecondarycase.[31]Allthreechildren'sisolateshadsimilarpulseeldgelelectrophoresisproles.[31]NoriskfactorswerefoundtobesignicantlyassociatedwithpositiveStaphylococcusaureusisolates.[31]AsecondstudywasconductedbyAdcocketaloftheprevalenceofMRSAcol-onizationattwochildcarecenters.[32]ThesetwocentershadachildhospitalizedforMRSAinfections.[32]Acultureoftheanteriornaresandaxillawastakenfromeachchildandchildcareprovider.[32]ParentsandchildcareproviderscompletedaquestionnaireaboutfactorsassociatedwithMRSAinfections.[32]Atdaycarecenterone,thecolonizationrateofMRSAwas24%anddaycarecentertwohadarateof3%.[32]AtdaycarecenteronetwostrainsofMRSAwereisolatedandwereasso-ciatedwithtwodierentclassrooms.[32]Atdaycentertwo,onestrainwasisolatedfromtheindexcaseandacolonizedchild.[32]Ofallchildren,60%hadcontactwithahealth-carefacilityorhadahouseholdmemberwhohadcontactwithahealth-carefacilitywithintwoyearspriortothestudy.[32]However,thisresultwasnotsignicantbecausetheP-valueistoolarge.[32]Twocommunitycolonizationprevalencestudieswerepreformed.TherstwasconductedbyHussain,Boyle-Vavia,andDuam.ThepurposeoftheirstudywastoascertainwhetherhealthychildrenattendinganoutpatientclinicwerecolonizedwithMRSA.[19]ThestudywasperformedataprimaryoutpatientfacilityatUniversityofChicagofromJanuarytoAugust1999.[19]Childrensixteenyearsandyoungerat-tendingtheclinicforwellchildvisitswereeligibleforthestudy.[19]Thoseeligiblehadspecimensobtainedfromthenaresandperineum.Ofthe500childrentested,24.4%werecolonizedwithStaphylococcusaureusandofthosecolonized,threeisolateshadMRSA.[19]TwooftheMRSAcolonizedchildrenhadapredisposingriskfactor.[19]25

PAGE 33

ThegeneralizablityofthestudyisinquestionduetothefactthatthisclinicwasintheinnercityinwhichthemajorityofpatientswereAfricanAmerican.[19]ThesecondcommunitycolonizationstudywasperformedbyNakamuraetal.ThestudywasconductedtoascertaintheprevalenceofnasalcarriageofMRSAinNashville,TN.[22]Childrenreceivingwellchildvisitsateitherauniversitypediatricclinicorprivatepediatricocewereeligibleforenrollmentregardlessofchronicmed-icalconditions.[22]Nasalswabswerecollectedandaquestionnairewasadministeredtocollectdemographicdataandriskfactors.[22]Ofthe500enrolledpatients,29%werecolonizedwithStaphylococcusaureusandofthosecolonizedpatients,fourwerecolonizedwithMRSA.[22]Noneofthepatientshadriskfactors,butallhadhouse-holdcontactswithriskfactors.[22]Theriskfactorsofthehouseholdcontactsthatwereanalyzedarechronicillness,hospitalization,employmentinthehealthcareinahospitalorlongtermcarefacility,andcommunityworndevice.[22]Oftheseriskfactors,onlyemploymentinahospitalorlongtermcarefacilitywassignicant.[22]TheMRSAisolatesweresusceptibletomanyantibioticsexcepterythromycin.[22]Sattler,Mason,andKaplanconductedaprospectiveobservationalstudytocom-parethepresenceofriskfactorsformethicillinresistancebetweenCA-MRSAandCommunity-AcquiredMethicillin-SensitiveStaphylococcusaureuspatientsandhouse-holdcontacts,aswellasthedemographicandclinicalcharacteristicsbetweenpa-tients.[2]ThestudywasconductedinHouston,TexasatTexasChildren'sHospitalfromFebruary2,2000toNovember14,2000excludingtwoonemonthperiodsinMayandSeptember.[2]Inpatientsandoutpatientswereeligibleiftheisolatewascommunity-acquired.[2]Patientswereexcludediftheyhadanyunderlyingillnesspre-disposingthemtofrequenthospitalizations,hospitalizationinthepriorsixmonths,infantslessthansixmonthsoldwhohadbeenhospitalizedduringtheneonatalpe-riodgreaterthan72hours,oroutpatientsurgerywithinthepastsixmonths.[2]Risk26

PAGE 34

factorswereassessedbyinterviewandincludedantibioticexposure,priorhospital-izations,health-carevisits,daycareattendance,health-careworkerornursinghomeresidentcontact,andpresenceofunderlyingillness.[2]Noneoftheseriskfactorswerefoundtobestatisticallysignicant.[2]Ofthe144enrolled,44%wereMRSA.ThisorganismwasmorefrequentlyrecoveredfromAfricanAmericans.[2]Methicillin-SensitiveStaphylococcusaureusinfectionstendedtobedeep-seatedwhencomparedtoMRSAinfections.[2]Recallbiasofthepresenceofriskfactorswasdecreasedbyexcludingpatientsiftheinvestigatororpatient'sguardianwereawareoftheantibioticsusceptibilitytestresults.[2]27

PAGE 35

CHAPTER4METHODS4.1StudyDesignThisisacross-sectionalstudyofchildren18yearsoryounger,whohaveapositiveStaphylococcusaureuscultureasanoutpatientorwithin72hoursofbecominganinpatientatAllChildren'sHospitalinSt.Petersburg,Florida.4.2InstitutionalReviewBoardThisstudyreceivedapprovalbytheInstitutionalReviewBoardatAllChildren'sHospitalACH#03-0747onJuly29,2003.ThestudywasalsosubmittedtotheInstitutionalReviewBoardatUniverisityofSouthFlorida,whodeferredapprovalofthestudytotheAllChildren'sHospitalInstitutionalReviewBoard.ThisstudywasperformedunderthesupervisionofRogerSanderson,theregionalepidemiologistfortheFloridaDepartmentofHealth.Theprincipleinvestigatorbecameano-cialDepartmentofHealthVolunteerandwasthereforegivenaccesstothemedicalrecords.PatientcondentialitywasassuredbynotremovingthemedicalchartsfromAllChildren'sHospitalgrounds.Limitedprivatehealthinformationwasenteredintothedatabaseinordertoensurethatthepatientsinthestudypopulationcouldnotbeidentied.Auniquenumberwasassignedbythedatabase,andtherefore,subjectsnamesanddatesofbirthwerenotabstractedfromthecharts.Theonlyuniquepa-tientinformationthatwasabstractedfromthemedicalchartswasdateofadmission28

PAGE 36

tothehospital,dateofculture,anddateofdischargefromthehospital.CoursesofHealthInsurancePortabilityandAccountabilityActHIPAAguidelinesandtheNationalInstituteofHealthProtectionofHumanSubjectswerealsotakenbythePrincipleInvestigator.4.3StudyPopulationAllpatientsadmittedtoAllChildren'sHospitalorseenasanoutpatientintheEmergencyroomatAllChildren'sHospitalSt.Petersburg,FloridafromJanuary1,2002toAugust20th,2003wereeligibleforentryintothestudy.RecordsafterAugust20wereunavailablebecausethehospitalinfectioncontroldepartmenthadnotyetupdatedtheirles.Inordertobeenrolledintothestudy,thepatientsalsomusthaveapositivecultureforStaphylococcusaureus.Positiveculturesfrominpatientshadtobecollectedwithin72hoursofbeingadmittedtothehospital.Patientswhowereadmittedmultipletimesduringthestudyperiodwhereonlyenrolledonceusingtherstadmissionwithapositivecultureresult.4.4InclusionCriteriaPatientswereenrollediftheywereunder18yearsofageatadmissionandhadapositiveStaphylococcusaureusculturewithintherst72hoursofadmissionorhadapositivecultureasanoutpatient.4.5ExclusionCriteriaSubjectswereexcludediftheirchartswereunavailableforreview.Chartswereun-availableifthepatientwascurrentlyhospitalizedorifthepatientsvisitedanoutpa-tientclinicassociatedwiththehospital.29

PAGE 37

4.6SourcesofDataAllofthedata,forthisstudy,wasobtainedfromachartreviewatAllChildren'sHospitalinSt.Petersburg,Florida.ThehospitalprovidedacomputergeneratedlistofallpositiveStaphylococcusaureusculturesforthestudyperiodofJanuary1,2002toAugust20,2003.Themedicalchartsofallpatientswhometthestudycriteriawerereviewed.4.7DataCollectionDatawascollectedbyperformingachartreviewof672patients.AllreviewswereperformedatAllChildren'sHospital.AstandardizedformwasmadeusingMicrosoftAccessandwasutilizedonallcharts.Theprincipleinvestigatorperformedallchartreviews.Patientcondentialitywasmaintainedbyensuringthatnoprivatehealthinfor-mationwasutilizedinthestudy.Nonamesordateofbirthswereabstractedfromthemedicalchartsinordertoassurepatientcondentiality.Allofthedatacollec-tiontookplaceatAllChildren'sHospitalandthechartswerepromptlyreturnedtomedicalrecordsafterdataentrywascompleted.SomeoftheinformationneededtoassessthepatientsriskforgettingaStaphy-lococcusaureusinfectionwasmissing.Themissinginformationwasmarkedas"notnoted"fortheparticularquestioninthedatabase.Seventeensubjectsoutof672hadsomemissingdatafromtheircharts.Thepercentageofchartsreviewedwithmissingdatawas2.5%.4.8DenitionsandClassicationofVariablesThefollowingvariableswerecollectedforthisstudyandaredenedbelow.30

PAGE 38

Age:Theageofapatientwasdeterminedasthesubjectsageatdateofculture.Race/Ethnicity:Thisvariablewascollectedasindicatedonthesubjectsmedicalchart.White,Black,Asian,AmericanIndian,orotherweredenedasraces.Eth-nicitywasdenedaseitherHispanicornon-Hispanic.Note:AllChildren'sHospitaldenedHispanicasaraceinmedicalrecords.Outcome/Transfer:Thisvariableidentiedwherethepatientwasgoingafterbeingdischargedfromthehospital.Thepossiblecategorieswerehome,long-termcarefacility,rehabilitationhospital,otherhospital,ordead.PreviousAntibioticUse:Previousantibioticusewasdenedasanyuseofantibioticswithintheprevious12monthsasnotedonthemedicalchart.PreviousSurgery:Thevariableisnotedasapatienthavinganysurgerywithinthepast12monthspriortothedateofculture.OutpatientSurgery:Outpatientsurgerywithintheprevious12monthspriortotheculture.PatientReceivingHomeHealthCare:Thevariablewasdenedasapatientreceivinghomehealthcarewithintheprevious12monthspriortothedateofculture.PreviousMRSAInfection:ThisvariablewasidentiedasapatienthavingapreviousinfectionwithMethicillin-ResistantStaphylococcusaureusasnotedonthemedicalchart.ResidentofaFacilitywithin12MonthsofAdmission:Apatientthatlivedinalong-termcarefacilityorrehabilitationhospital12monthspriortotheculturedate.CommunityWornDeviceattheTimeofAdmission:Thesedevicesweredenedasdialysis-related,urinary/foleycatheter,PICline,Centralline,andotherlinesPEG,Jtube,shuntsinplaceatthetimeofadmission.Endotrachealtubeswerealsoincludedinthe"other"category.31

PAGE 39

CardiovascularDisease:Apatientwithanyhistoryofarteriovenousmalfor-mations,congenitalheartdefects,pulmonaryatresia,orScimitarsyndromeasnotedonthemedicalchart.LiverDisease:Apatientwithanyhistoryofacutehepatitis,oranycongenitalabnormalitiesoftheliverasnotedonthemedicalchart.PulmonaryDisease:Ahistoryofasthma,cysticbrosis,orbroncho-pulmonarydysplasiaasnotedonthepatient'smedicalchart.NeurologicDisease:Apatientwithahistoryofanyencephaly,skullorspinaldeformities,cerebralpalsy,Down'ssyndrome,ordemyelinatingdiseaseasnotedonthemedicalchart.ImmunoTherapy:Apatientwhowasundergoingtreatmentwithcorticos-teroidsorchemotherapy/radiationtherapywithintheprevious12monthsasnotedonthemedicalchart.ChronicDermatologicalCondition:Apatientwithanyhistoryofeczema,psoriasis,dermatitis,ordecubitusulcersasnotedonthemedicalchart.4.9StatisticalAnalysisDataforthestudywasanalyzedwiththeEpiInfosoftwarepackagefromtheCentersofDiseaseControlandStatisticalAnalysisSoftwareSAS.Thedatawasanalyzedbothdescriptivelyandanalytically.Thefrequenciesforthedemographiccharacteris-ticsaswellastheriskfactorswereobtained.UnivariateAnalysiswasconductedforeachriskfactorandacrudeoddsratioanda95%condenceintervalwereobtainedfromEpiInfo.Racespecicanalysiswasthenconductedwhichsuggestedthateectmodicationmaybepresent.Analysiswasconductedutilizingthelogisticregressionfunction,proclogisticinSAStoassessifracewasaneectmodierforanyofthe32

PAGE 40

riskfactors.Thisanalysisconrmedthatracewasaneectmodierforthevariablepreviousantibioticuse.Thelogisticregressionfunctionwasalsousedtoadjusttheriskfactorsforthepresenceofconfounding.Avariablewascreatedtoreectmultipleexposurestohealthcaretodetermineifriskincreasedasthenumbersofpotentialexposuresincreased.Thetotalnumberofriskfactorsforeachsubjectwastabulatedandanalysiswaspreformedlookingforadoseresponserelationship.Thesubjectswerebrokenintofourcategories:thosewithnoriskfactors,1riskfactor,2riskfactors,andgreaterthan2riskfactors.Eachgroupwascomparedwiththethenoriskfactorgroup.Thesameprocedurewasutilizedtoadjustforconfoundingandassessifeectmodicationwaspresentaswasoutlinedabove.33

PAGE 41

CHAPTER5RESULTS5.1DemographicCharacteristicsDemographiccharacteristicsofthestudyparticipantsareindicatedinTable1.Inthisstudyatotalof672chartswerereviewedandtherewere126casesofMRSAinfection.TheresultsareshownasthetotalstudypopulationandthenbrokenintothosewithMSSAandMRSA.Age:Subjectswereenrolledinthestudyiftheywere18yearsoldoryoungeratthetimeofadmission.Foranalysis,agewasbrokeninto5categories:lessthan1yearold,1-4yearsold,5-9yearsold,10-14yearsold,and15-18yearsold.The1-4yearoldgroupwasthelargestinthestudyandthe15-18yearoldgroupwasthesmallest.TheseagecategorieswerechoseninordertomaintainconsistencywithCDCandFloridaDepartmentofHealthagereportingstandards.Table1showsthedistributionofageasawholegroupaswellasacomparisonoftheMRSAandMSSAgroups.Race:Allracesandethnicitieswereeligibleforthestudy.Themajorityofsubjectswerenon-Hispanicwhites,followedbyblack,thenHispanicwhites.Table1showsthebreakdownofthestudypopulationbyrace.WhencomparedwiththetotalpopulationbyraceinPinellascounty,7.7%ofofthecountypopulationisblackand2.4%areHispanicinthetotalpopulationascomparedwiththestudypopulationwhere15.2%areblackand9.1%areHispanic.Theracebreakdowninthestudy34

PAGE 42

Total MRSA MSSA Number% Number% Number% Age lessthan1yr 8412.5 1214.3 7285.7 1-4yr 24336.2 5823.9 18576.1 5-9yr 19929.6 2613.1 17386.9 10-14yr 10415.5 2019.2 8480.8 15-18yr 426.2 1023.8 3276.2 Race White 48271.7 7415.4 40884.6 Black 10215.2 3635.3 6664.7 Asian 111.6 19.1 1090.1 Hispanic 619.1 1016.4 5183.6 Other 162.4 531.3 1168.7 Gender Male 42463.1 7116.7 35383.3 Female 24836.9 5522.2 19377.8 RiskFactors CommunityWornDevice 8112.1 2834.6 5365.4 PreviousAntibioticUse 21031.3 5325.2 15774.8 HomeHealthCare 233.4 1252.2 1147.8 PreviousHospitalization 19028.3 5629.5 13470.5 PreviousMRSAInfection 365.4 1644.4 2055.5 PreviousSurgery 14126.9 4129.1 10070.9 PreviousOutpatientProcedure 568.3 1425.0 4275.0 Immunotherapy 172.5 211.8 1588.2 ResidenceinaFacility 172.5 635.3 1164.7 MedicalConditions Cancer 131.9 215.4 1184.6 CardiovascularDisease 223.3 836.4 1463.6 ChronicDermatologicalConditions 456.7 1022.2 3577.8 Diabetes 60.9 116.7 583.3 LiverDisease 91.3 444.4 555.6 NeurologicDisease 7210.7 1926.4 5373.6 PulmonaryDisease 18126.9 3720.4 14479.6 Table1.Characteristicsofstudyparticipantsage18oryoungerseenatAllChildren'sHospital1/1/02-8/20/03intotalandbymethicillinstatus.35

PAGE 43

OddsRatio 95%CondenceInterval Riskfactors CommunityWornDevice 2.65 1.60,4.41 PreviousAntibioticUse 1.79 1.40,2.20 HomeHealthCare 5.12 4.28,5.96 PreviousHospitalization 2.46 2.06,2.86 PreviousMRSAinfection 3.83 1.92,7.62 PreviousSurgery 2.15 1.72,2.58 Black 2.98 2.51,3.45 Female 1.42 0.95,2.10 MedicalConditions CardiovascularDisease 2.58 1.74,3.47 ChronicDermatologicalConditions 1.26 0.53,1.99 NeurologicDisease 1.65 1.09,2.22 PulmonaryDisease 1.16 0.32,2.00 TotalRiskFactors 0RiskFactorsPresent 1.00 1RiskFactorPresent 1.30 0.79,1.81 2RiskFactorsPresent 2.45 1.83,3.07 greaterthan2RiskFactorsPresent 5.82 5.26,6.38 Table2.OddsRatiosandCondenceIntervalsforRiskFactorsforMRSAinfectionsinchildrenage0-18yearsatAllChildren'sHospital1/1/02-8/20/03.populationiscomparablewithFloridaandUnitedStates,with14.6%blackinFloridaand12.3%blackintheUnitedStates.Hispanicsmakeup16.8%ofthepopulationinFloridaand12.5%intheUnitedStates.Gender:ThebreakdownofthestudypopulationbygenderisshowninTable1.Inthisstudy36.9%ofthesubjectswerefemale.ThisissignicantlylowerthaninPinellascounty3.3%,Florida1.2%,andtheUS.9%.5.2RiskFactorsforMethicillin-ResistantStaphylococcusaureusDataforeightriskfactorswerecollectedfromeachsubjectsmedicalchart.Theriskfactorswerecommunityworndevice,previousantibioticuse,homehealthcare,previoushospitalization,previoussurgery,previousMRSAinfection,immunotherapy,36

PAGE 44

andresidenceinafacility.Table1showsthebreakdownonthedistributionoftheriskfactorsbytotalpopulationandabreakdownbymethicillinresistancestatus.Thevariableresidenceinafacilityandimmunotherapywerenotanalyzedduetothesmallnumberofsubjectswiththeseriskfactors.Table2showsthecrudeoddsratiosandthe95%condenceintervalsforeachoftheriskfactors.GenderwasfoundnottobeassociatedwithMRSAinfectionsOR=1.42,CI=0.95,2.10Table2.BlackswerefoundtobeatagreaterrisktobediagnosedwithanMRSAinfectionthanwhitesOR=2.98,CI=2.51,3.45.Table2CommunityworndeviceOR=2.65,CI=1.60,4.41,previousantibioticuseOR=1.79,CI=1.40,2.20,homehealthcareOR=5.12,CI=4.28,5.96,previoushospitalizationOR=2.46,CI=2.06,2.86,previousMRSAinfectionOR=3.83,CI=1.92,7.62,andprevioussurgeryOR=2.15,CI=1.72,2.58wereallfoundtobestatisticallysignicantriskfactorsforMRSAinfection.5.3MedicalConditionsItwashypothesizedthatcertainmedicalconditionsmaypredisposesubjectstoanMRSAinfection.Thesemedicalconditionswerecancer,cardiovasculardisease,chronicdermatologicalconditions,diabetes,liverdisease,neurologicaldisease,andpulmonarydisease.Table1showsthebreakdownofmedicalconditionsinthetotalstudypopula-tionandbymethicillinstatus.Cancer,liverdisease,anddiabeteswerenotanalyzedduetothesmallnumberofsubjectsthatdemonstratedthesedisorders.Table2demonstratedthecrudeoddsratiosand95%condenceintervalsforeachofthemedicalconditionsthatwereanalyzed.Ofthese,onlycardiovasculardiseaseOR=2.58,CI=1.74,3.47andneurologicdiseasesOR=1.65,CI=1.09,2.22wereshowntobeassociatedwithMRSAinfectionTable2.Thereasonthatthesemedicalcon-37

PAGE 45

ditionsareassociatedwithMRSAinfectionisthattheyoftenrequiremorefrequentcontactwithhealthcareprovidersinordertomonitorandtreattheirillness.5.4TotalRiskFactorsAsmanyoftheriskfactorsofinterestreectopportunitiestoacquirehospitalbasedinfections,avariablewascreatedtoreectmultipleexposurestocaretodetermineifriskincreasedasthenumbersofpotentialexposuresincreased.Thetotalnumberofriskfactorsforeachsubjectwastabulatedandanalysiswaspreformedlookingforadoseresponserelationship.Thesubjectswerebrokenintofourcategories:thosewithnoriskfactors,1riskfactor,2riskfactors,andgreaterthan2riskfactors.Eachgroupwascomparedwiththethenoriskfactorgroup.Themoreriskfactorsthatasubjectpossessed,thegreatertheirriskforMRSAinfectionTable2.Therewereonly35outof126MRSApatientsthathadnoriskfactorsforMRSAinfectiondocumentedintheirchart.Thisisaprevalenceof28%.ThisndingdemonstratesthatthemajorityofMRSAinfectionsinthisstudywereassociatedwithsomekindofpreviousexposuretothehealthcaresettingandwerenottrulycommunityacquiredinfections.5.5EectModicationTestingforeectmodicationwasperformedinSASbecauseunivariateanalysissug-gestedthatracemaybeaneectmodierfortheriskfactors.Eectmodicationwastestedbetweenraceandallriskfactors.Racewasaneectmodieronlyfortheriskfactorofpreviousantibioticusepvalue=.02.Thisndingsuggeststhatraceplaysaroleinasubjectsaccesstoantibiotics.Thisndingmaybeexplainedbythefactthatwhitestraditionallyhavemoreaccesstohealthcarethanblacks.Thiswouldgive38

PAGE 46

Total MRSA MSSA Number% Number% Number% Age lessthan1yr 1716.7 529.4 1270.6 1-4yr 3433.3 1441.2 2058.8 5-9yr 2019.6 735.0 1365.0 10-14yr 2524.5 832.0 1768.0 15-18yr 65.9 233.3 466.7 Gender Female 3938.2 1948.7 2051.3 RiskFactors CommunityWornDevice 1413.7 857.1 642.9 PreviousAntibioticUse 2827.5 1864.3 1035.7 HomeHealthCare 54.9 360.0 240.0 PreviousHospitalization 3534.3 1645.7 1954.3 PreviousMRSAInfection 43.9 250.0 250.0 PreviousSurgery 2019.6 1155.0 945.0 TotalRiskFactors 0RiskFactors 4948.0 1224.5 3775.5 1RiskFactors 2827.5 828.6 2030.3 2RiskFactors 98.8 616.7 371.4 greaterthan2RiskFactors 1615.7 1062.5 637.5 Table3.Characteristicsofblackstudyparticipantsage18oryoungerseenatAllChildren'sHospital1/1/02-8/20/03intotalandbymethicillinstatus.whitechildrenmoreexposuretohealthcareasatotalpopulation.Itmaybehypoth-esizedthatonlythesickestofblackchildrenareexposedtohealthcareandasaresultmoresusceptibletoMRSAinfectionTable3andTable4illustratesthebreakdownofeachoftheriskfactorswithintheirrespectiveraceasatotalpopulationandbymethicillinstatus.Asaresultofeectmodicationofracebeingpresent,subjectswerecategorizedaccordingtoraceandthenoddsratiosandcondenceintervalswerecomputed.Thisanalysiswasperformedonblacksandwhites.Hispanicswerein-cludedwiththewhitepopulation.Allotherracesandethnicitieswerepresentintoosmallnumberstopermitanalysis.TheriskfactorsthatweresignicantinwhiteswerehomehealthcareOR=6.12,CI=5.16,7.08,communityworndeviceOR=2.28,39

PAGE 47

Total MRSA MSSA Number% Number% Number% Age lessthan1yr 6011.1 58.3 5591.7 1-4yr 19936.7 4221.1 15778.9 5-9yr 17231.7 1810.4 15489.6 10-14yr 7814.4 1215.4 6684.6 15-18yr 346.3 720.6 2779.4 Gender Female 19836.5 3417.2 16482.8 RiskFactors CommunityWornDevice 6311.6 1727.0 4673.0 PreviousAntibioticUse 17331.9 3117.9 14282.1 HomeHealthCare 183.3 950.0 950.0 PreviousHospitalization 14426.5 3625.0 10875.0 PreviousMRSAInfection 295.3 1137.9 1862.1 PreviousSurgery 11921.9 2823.5 9176.5 TotalRiskFactors 0RiskFactors 22140.7 2210.0 19990.0 1RiskFactors 19335.5 2714.1 16685.9 2RiskFactors 6512.0 1116.9 5483.1 greaterthan2RiskFactors 6311.6 2438.1 3961.9 Table4.Characteristicsofwhitestudyparticipantsage18oryoungerseenatAllChildren'sHospital1/1/02-8/20/03intotalandbymethicillinstatus.40

PAGE 48

White Black OddsRatioCI OddsRatioCI Female 1.220.74,1.70 2.571.73,3.41 RiskFactors HomeHealthCare 6.125.16,7.08 2.951.11,4.79 CommunityWornDevice 2.281.67,2.89 2.851.71,4.01 PreviousHospitalization 2.431.95,2.91 1.981.13,2.83 PreviousMRSAInfection 3.692.90,4.48 1.88-0.12,3.89 PreviousSurgery 2.021.51,2.53 2.791.79,3.79 PreviousAntibioticUse 1.310.81,1.79 5.604.66,6.54 TotalRiskFactors 0 1.00 1.00 1 1.230.63,1.83 1.230.18,2.28 2 1.841.06,2.62 6.174.03,7.70 greaterthan2 5.574.90,6.24 5.143.94,6.34 Table5.OddsRatiosand95%CondenceIntervalsforSubgroupAnalysisofBlackandWhiteofChildrenages0-18yearsfromAllChildren'sHospital1/1/02-8/20/03CI=1.67,2.89,previoushospitalizationOR=2.43,CI=1.95,2.91,previousMRSAinfectionOR=3.69,CI=2.90,4.48,andprevioussurgeryOR=2.02,CI=1.51,2.53Table5.Alloftheseriskfactorsincreasedthesubjectscontactwithhealth-careandthereforeincreasedthelikelihoodofacquiringMRSAinfection.Inblacks,pediatricfemalesweremorelikelytohaveMRSAOR=2.57,CI=1.73,3.41.Thisndingmaybeduetothesmallsamplesizeofblackchildreninthestudy.Oftheanalyzedriskfactors,homehealthcareOR=2.95,CI=1.11,4.79,communityworndeviceOR=2.85,CI=1.71,4.01,previoushospitalizationOR=1.98,CI=1.13,2.83,previoussurgeryOR=2.79,CI=1.79,3.79,andpreviousantibioticOR=5.60,CI=4.66,6.54usewereallsignicantriskfactorsinblacksTable5.WiththeseriskfactorscontactwiththehealthcareenvironmentandhealthcareworkersisincreasedandthereforeincreasesthepossibilityofacquiringanMRSAinfection.41

PAGE 49

White Black OddsRatio95%CI OddsRatio95%CI Age 0.980.93,1.03 1.000.92,1.10 Female 1.190.72,1.95 1.880.72,4.90 PreviousAntibioticUse 1.100.65,1.86 5.131.75,15.08 CommunityWornDevice 0.980.46,2.09 0.930.18,4.88 HomeHealthCare 4.371.55,12.32 1.960.19,20.84 PreviousMRSAInfection 2.861.16,7.05 0.650.06,6.98 PreviousHospitalization 2.001.14,3.50 0.770.25,2.41 PreviousSurgery 1.250.68,2.29 1.940.50,9.56 1TotalRiskFactor 1.470.80,2.67 1.300.45,3.76 2TotalRiskFactors 1.850.84,4.05 5.501.16,26.16 greaterthan2TotalRiskFactors 5.362.74,10.49 4.191.20,14.61 Table6.AdjustmentofConfoundingforBlackandWhiteofChildrenages0-18yearsfromAllChildren'sHospital1/1/02-8/20/035.6ConfoundingLogisticregressionwasusedtoadjustforconfounding.Adjustmentofconfoundingwasperformedforeachraceduetothepresenceofeectmodication.Aftertheadjustmentforconfoundinginwhites,onlyhomehealthcareOR=4.37CI=1.55,12.32,previousMRSAinfectionOR=2.86CI=1.16,7.05,andprevioushospital-izationOR=2.00CI=1.14,3.50remainedstatisticallysignicantTable6.Inblacks,afteradjustmentofconfounding,onlypreviousantibioticuseOR=5.13CI=1.75,15.08remainedsignicant.Adjustmentforconfoundingwasalsopreformedonthetotalriskfactorsmodel.AdoseresponserelationshipwaspresentwithincreasingriskfactorspresentTable6.42

PAGE 50

CHAPTER6DISCUSSION6.1FindingsTheresultsofthisstudyindicateseveralfactorsinthepopulationofpediatricpatientsthatleadtoMRSAinfection.Inregardstodemographiccharacteristics,blackchildrenare2.98timesmorelikelytohaveanMRSAinfectionthanwhitechildren.Genderandagewerenotriskfactorsforthedevelopmentoftheinfection.TheriskfactorsthatweresignicantinwhiteswerehomehealthcareOR=6.12,CI=5.16,7.08,communityworndeviceOR=2.28,CI=1.67,2.89,previoushospitalizationOR=2.43,CI=1.95,2.91,previousMRSAinfectionOR=3.69,CI=2.90,4.48,andprevioussurgeryOR=2.02,CI=1.51,2.53.Inblacks,femalesweremorelikelytohaveMRSAOR=2.57,CI=1.73,3.41.Thisndingmaybeduetothesmallsamplesizeofblackchildreninthestudy.Oftheanalyzedriskfactors,homehealthcareOR=2.95,CI=1.11,4.79,communityworndeviceOR=2.85,CI=1.71,4.01,previoushospitalizationOR=1.98,CI=1.13,2.83,previoussurgeryOR=2.79,CI=1.79,3.79,andpreviousantibioticOR=5.60,CI=4.66,6.54usewereallsignicantriskfactorsinblacks.Eectmodicationwastestedbetweenraceandallriskfactors.Racewasaneectmodieronlyfortheriskfactorofpreviousantibioticusepvalue=.02.Racemaybeanaectmodierduetothefactthatblacksmaybemorelikelytoutilizeemergencyroomsandurgentcarecenterstohavetheirchildtreatedforanillness.Whitesaretraditionallyknowntohavebetterand43

PAGE 51

moreassesstohealthcareandmaythereforebemorelikelytotaketheirchildtoadoctorsocethantaketheirchildtotheemergencyroomtohaveanillnesstreated.Adjustmentofconfoundingwasperformedforeachraceduetothepresenceofeectmodication.Aftertheadjustmentforconfoundinginwhites,onlyhomehealthcareOR=4.37CI=1.55,12.32,previousMRSAinfectionOR=2.86CI=1.16,7.05,andprevioushospitalizationOR=2.00CI=1.14,3.50remainedstatisticallysignicant.Inblacks,afteradjustmentofconfounding,onlypreviousantibioticuseOR=5.13CI=1.75,15.08remainedsignicant.Adjustmentforconfoundingwasalsopreformedonthetotalriskfactorsmodel.Adoseresponserelationshipwaspresentwithincreasingriskfactorspresent.Ascomparedtothisstudy,theresultsofotherMRSAstudiesonadultshadsomediscrepanciesandsomesimilarities.AbuduetalconductedastudycomparingMRSAandMSSAwithregardtoprevioushospitalization,recentantibioticuse,andanycontactwithahealthcarefacility.[27]Noneofthoseriskfactorswerefoundtobestatisticallysignicant.[27]ThisiscontradictorytothecurrentstudywhichdemonstratedmanyriskfactorsthatweresignicanttothedevelopmentofMRSAinfections.Theinconsistencymaybeexplainedbyapoorresponserateof58%whichsuggestsastronglikelihoodofthepresenceofselectionbias.[27]AstudyconductedbyMorinandHadlerfoundanincreaseoftheincidenceofMRSAinmalesandblacks.[29]GenderwasnotfoundtobeariskfactorforMRSAinfectioninthecurrentstudy.Thediscrepancywithregardtogendermaybeexplainedbythetypeofstudythatwasconductedwhichonlyincludedpatientswithbacteremiaandexcludedallpatientswithothertypesinfections.[29]However,boththecurrentstudyandtheMorinandHadlerstudyfoundracetobeariskfactorforMRSAinfection.[29]AstudyconductedbyJohnsonetalreportedanincreaseriskwithprevioushospitalizationandresidenceinafacility.[17]Theseresultsareconsistantwiththisstudyexcept44

PAGE 52

forthefactthattherewerenotenoughpatientswhoresidedinafacilitytopermitstatisticalanalysis.GrundmannetalreportedanincreaseriskofMRSAinfectionwithprevioushospitalizationandpatientswithdiabetes.[28]Therewerenotenoughpatientswithdiabetesinthisstudytopermitstatisticalanalysisbutitwasfoundthatprevioushospitalizationwasstatisticallysignicant.Ascomparedtothecurrentstudy,theresultsofotherstudiesofMRSAonchildrenshowedsomesimilaritiesaswellassomediscrepancies.ThestudybySattleretalfoundthatblacksweremorelikelytohaveMRSAthanwhitesorHispanics,whichisconsistentwiththeresultsofthisstudy.[2]ThestudybySattleretaldidalsoreportthattherewasnosignicantdierencesintheexposuretoriskfactorsbetweentheMRSAandtheMSSAgroup.[2]ThisndingisinconsistentwiththecurrentstudywhichfoundsignicantriskassociatedwithMRSAforthosewithmanyoftheriskfactorsaswellasrace.Thisdiscrepancymaybetoduethesmallsamplesizeof144subjectsoftheSattleretalstudy.[2]HeroldetalfoundanassociationbetweenageandMRSA,89%oftheMRSAisolateswerefromchildrenagesthreeto36monthswhichwashypothesizedtobearesultofthechildrens'exposuretoadaycaresetting.[1]ThisisnotconsistenttotheresultsinthisstudyinwhichagewasnotfoundtobeariskfactorforMRSA.Thisdiscrepancymaybeduetothesmallsamplesizeof88subjectsaswellasthespecializationofthehospitalwherethestudywasconducted.[1]ThestudywasconductedatUniversityofChicagoChildren'sHospitalwhichisatertiarycarepediatrichospitalintheinnercityofChicago.[1]HeroldetalalsoreportedanincreaseofMRSAinfectioninblackswhichisconsistentwiththendingsofthisstudy.[1]ThestudyconductedbyCampbelletalfoundthatmalesweretwiceaslikelytohaveCA-MRSA.[21]CampbelletalalsofoundtheCA-MRSApatientsweremorelikelytobeolderandtohavereceivedantibioticspriortoadmission.[21]Ageandgenderwerenotfoundtoberiskfactorsinthecurrent45

PAGE 53

studybutpreviousantibioticuseandcommunityworndevicewerefoundtobeariskfactor.Thediscrepancybetweenthestudieswithregardtogenderandagemaybeexplainedbythesmallsamplesizeof62subjectsbytheCampbelletalstudy.[21]6.2Strengths&WeaknessesoftheStudyThestrengthsofthisstudyarethelargesamplesizewhichincreasesthepowerofthestudy.The20monthlengthofthestudyperiodisalsoastrength.Thecross-sectionaldesignusedinthisstudyallowedfortheevaluationofmultipleriskfactors.Acrosssectionalstudyenablestheresultingdatafromthestudytobeutilizedtocalculateprevalenceestimatesofexposureanddisease.Aweaknessofthestudyisthatitwasonlyperformedatonehospital.Theresultsmustbegeneralizedwithcaution.ThepopulationmaynotcloselymirrorthepediatricpopulationofPinellascountyorthestateofFloridaduetothehighamountoftransferstoAllChildren'sHospitalfrommanyoftheadjacentcounties.Thismayresultinthehospitalhavinganoverallsickerpopulationthanotherpediatricpopulationsseeninotherhospitals.Themainweaknessofthecrosssectionalstudydesignisthattemporalsequencebetweenexposureanddiseasecanbediculttoestablish.Thiswasnotanissueinthisstudybecausetheriskfactorsthatwerecollectedwerespecicallydenedashavingtakenplaceintheprevious12monthspriortothepositiveculture.Thereisalsoaquestionofaccuracyofthemedicalchartstoreectthepresenceofthesubjectsriskfactors.Severalpatientswerenotlistedashavingpreviousantibioticusewhentheirhistoryanddiagnosiswouldsuggestotherwise.Thismayhaveleadtomisclassicationofthosepatientswithregardstoexposurestatus.46

PAGE 54

Therearetwomaintypesofbiasthatmayhaveplayedaroleinthisstudy.Therstisselectionbiaswhichoccurswhenthoseenrolledinthestudycauseanassoci-ationtobepresentorabsentwheninrealitytheoppositeistrue.Thiscouldhaveoccurredasaresultofthechartsthatwereunavailableforreview.ThechartsthatwereunavailablewerethoseofpatientscurrentlyhospitalizedandthoseofpatientsonlyseenintheoutpatientclinicsassociatedwithAllChildren'sHospital.Outof827chartsthatwererequested155ofthemwereunavailableforreview.Themostcom-monreasonwasthatthechildwasseenintheoutpatientclinic.Thisisapproximatelyan82%responserate.Thiscouldhaveintroducedsomeselectionbiasintothestudy.Theothertypeofbiasthatmayhaveplayedaroleinthisstudywasinformationbiaswhichoccurswhentheinformationaboutthesubjectsenrolledinthestudyisincorrectormissing.Thismaycauseasubjecttobeclassiedincorrectlyinregardstoeitherexposureoroutcomecausingmisclassicationbias.InthisstudytheremayhavebeeninadequatedocumentationofthepresenceofriskfactorsforMRSA.Infor-mationbiascanalsooccurwheninformationonotherpossibleconfoundingfactorsisnotavailablebecauseofthelimitedamountofdatacollectedinthechart.Thiscouldbethecasewithsomeoftheriskfactorsthatwerelistedinotherstudies.Forexample,child'sattendanceindaycareandfamilymember'sexposuretohealthcareareriskfactorsthatcouldhavecreatedbias.Informationbiascanalsobecausedbyamisclassicationaccordingtodiseasestatus.ThiscouldresultinapatientwithMRSAnotbeingidentiedassuch.Informationbiascouldhappeniftherewasaninstrumentmalfunctionorifthemedicaltechnologistenteringtheresultsmadeatypographicalerror.Someothertypesofbiasthatmaybepresentarerecallbiasandinterviewerbias.Recallbiasoccurswhenthereisinaccuraterecallofpastexposure.Thiscouldbeacommonproblemwhenaparentismoreworriedabouttheimmediatewelfareof47

PAGE 55

theirchildthanthequestionsthatarebeingaskedbythedoctorornursellingoutthepaperwork.ItispossiblethattheamountofrecallbiascoulddierbywhetherthechildhadMRSAorMSSA.Thismaybearesultofthechildwiththeresistantinfectionhavingmorecontactwithhealthcareandthereforetheparentwouldbemorelikelytorecallthepresenceofriskfactorsintheirchild.Interviewerbiasisatypeofinformationbiasinwhichthemeansforobtainingtheinformationaboutthestudysubjectleadstoincorrectassessmentofexposureordiseasestatus.Thistypeofbiascouldhaveoccurredinthisstudyasaresultofeachsubjectnothavingthesamenurseordoctorinterviewthem.Eachhealthcareprofessionalhasadierentwayofcompletingthenecessaryforms.Thisaloneisenoughtointroduceinterviewerbias.6.3FutureDirectionsManyofthepreviousstudiesmentionedthatthesusceptibilitypatternsweresimilarinCA-MRSAandnosocomialMRSAisolates.[30,17,33,27,18,28,22,19,34,2,1]ThissuggeststhattheinfectionswerereallytheresultofthesamestrainofMRSA.MRSAthatisnosocomiallyacquiredtypicallyisresistanttomultipleantibioticswhereCA-MRSAisonlytypicallyresistanttopenicillinandmethicillin.[30,17,33,27,18,28,22,19,34,2,1]Thereforeitisimportanttoassessthepatientprevi-oushealthcareexposureinordertodistinguishbetweenCA-MRSAandnosocomialMRSA.Assessingthisexposurehasbeenmademoredicultwiththeincreaseinoutpatientproceduresandthedecreaseinoverallhospitalstaysformanysurgeries.Thisdecreaseorabsenthospitalstaymayleadtopoorpatientrecallaswellasanincreaseinthepatientsexposuretohomehealthcareorfrequentdoctor'socevisitsforfollow-upfurtherincreasingthepatientexposuretohealthcare.Thereisalsoanincreaseintheuseofbroadspectrumantibiotics.[15,35]Thisincreasestheselec-48

PAGE 56

tivepressureofStaphylococcusaureusandotherbacteriaandleadstoincreasesinantimicrobialresistance.[15,35]Currently,themedicaldenitionofCA-MRSAisanyoutpatientisolateoraninpatientisolatethatisculturedwithin48to72hoursofadmissiontoahospital.ThisdenitionneedstomodiedtotakeintoaccountmanyofthepredisposingriskfactorssoamoreaccurateprevalenceoftrueCA-MRSAcanbeassessed.ThiscanbedonebyalteringthedenitionofnosocomialMRSAtoincludepatientswiththeseriskfactors.AtermofhealthcareassociatedMRSAcouldbeutilizedinsteadofnosocomial.[18]ThiswouldresultinthetermCA-MRSAbeingutilizedonlyforpatientswithMRSAandnopredisposingriskfactors.TherewasalsoanarticlerecentlypublishedontheBBCNewswebsitethatsug-gestedthatMRSAmaybecarriedbypets.[36]Therewasnosuggestionastohowtheanimalsacquiredtheinfection.[36]Cats,dogs,andrabbitsalltestedpositiveforcolonizationofMRSA.[36]ThisarticleisanotherreasonwhythereisaneedformorestudiesonMRSAandtheriskfactorsassociatedwithitstransmission.[36]ThereshouldalsobemoreintensivestudiesfocusedintheareasofdaycarecentersandthepossiblespreadofCA-MRSAandtheroleofhouseholdcontactsinthespreadofCA-MRSA.SomestudieshavesuggestedalinkbetweenCA-MRSAanddaycarecenters.[32,31]Thesestudiesfoundnothingstatisticallysignicanttosuggestthatdaycareplayedaroleinthespreadoftheinfection.[32,31]TherewerenostudiesthatsolelyfocusedontheroleofhouseholdcontactsandCA-MRSAinchildren.Anotheraspectthatmeritsfurtherstudyistherelationshipbetweenparents'orcaregivers'occupationandMRSAinfection.IthasbeenhypothesizedthatparentswhoworkinthehealthcareindustryarelikelytobecolonizedwithMRSAandasaresultcolonizetheirchildren.[2,22]ThiswouldincreasethelikelihoodofthechildrentodevelopanMRSAinfection.Ifthesestudiesarecarriedoutwemayndabetterwaytopredict49

PAGE 57

patientsthatmayhaveMRSAandthereforestartadequatetreatmentmorequicklyandpreventchildrenfromdying.50

PAGE 58

REFERENCES[1]HeroldBC,ImmergluckLC,alMCMaranan.Community-acquiredMethicillin-ResistantStaphylococcusaureusinChildrenwithnoIdentiedPredisposingRiskJournaloftheAmericanMedicalAssociation.1998;279:593{598.[2]SattlerCA,Jr.EO.Mason,KaplanSL.ProspectivecomparisonofRiskFac-torsandDemographicandClinicalCharacteristicsofCommunity-Acquired,Methicillin-ResistantversusMethicillin-SusceptibleStaphylococcusaureusinfec-tionisChildrenPediatricInfectiousDiseaseJournal.2002;21:910{916.[3]GorakEJ,YamadaSM,BrownJD.Community-AcquiredMethicillin-ResistantStaphylococcusaureusinHospitalizedAdultsandChildrenwithoutKnownRiskFactorsClinicalInfectiousDiseases.1999;29:797{800.[4]MacdonaldA,SmithG.,eds.Thestaphylococci:proceedingsoftheAlexanderOgstonCentennialConference.AberdeenUniversityPress1981.[5]TalaroK,TalaroA.FoundationsinMicrobiologych.18,:550{579.Wm.C.BrownPublishers1996.[6]EnrightMC,RobinsonDA,RandleG,FeilEJ,GrundmannH,SprattBG.TheEvolutionaryHistoryofMethicillin-ResistantStaphylcoccusaureusinProceed-ingsoftheNationalAcademyofSciences;99:7687{76922002.[7]LowyFD.StaphylococcusaureusInfectionsNewEnglandJournalofMedicine.1998;339:520{532.[8]PartI.EvolutionofIsolationPracticesAvailableat:http://www.cdc.gov/ndidod/ISOLAT/isopart1.htm.AccessedJuly15,2003.[9]DeikemaDJ,PfallerMA,alFJSchmitz.SurveyofInfectionsduetoStaphylococ-cusspecies:FrequencyofOccurenceandAntimicrobialSusceptibilityofIsolatesCollectedintheUnitedStates,Canada,LatinAmerica,Europe,andtheWesternPacicRegionfortheSENTRYAntimicrobialSurveillanceProgram,1997{1000ClinicalInfectiousDiseases.2001;32:S114{S132.[10]KluytmansJ,BelkunA,VerbrughH.NasalCarriageofStaphylococcusaureus:Epidemiology,UnderlyingMechanisms,andAssociatedRisksClinicalMicrobi-ologyReviews.1997;10:505{520.51

PAGE 59

[11]SaravolatzLD,MarkowitzN,ArkingLM,PohlodDJ,FisherE.Methicillin-ResistantStaphylococcusaureus:EpidemiologicObservationsduringaCommunity-AcquiredOutbreakAnnalsofInternalMedicine.1982;96:11{16.[12]HealthFloridaDepartment.GuidelinesforControlofAntibioticResistantOr-ganisms1999.[13]DiseaseControlCenters,Prevention.RecommendationsforPreventingtheSpreadofVancomycinResistanceRecommendationsoftheHospitalInfectionControlPracticesAdvisoryCommitteeMMWR.1995;55:1{13.[14]MutoCA,JeriganJA,alBEOstrowshy.SHEAGuidelineforPreventingNosoco-mialTransmissionofMultidrug-ResistantStrainsofStaphylococcusaureusandEnterococcusInfectionControlandHospitalEpidemiology.2003;24.[15]HiramatsuK,CuiL,KurodaM,ItoT.TheEmergenceandEvolu-tionofMethicillin-ResistantStaphylococcusaureusTrendsinMicrobiology.2001;9:486{493.[16]RezendeNA,BlumbergHM,MetzgerBS,LarsenNM,RaySM,McGowanJE.RiskFactorsforMethicillin-ResistanceamongPatientswithStaphylococcusau-reusBacteremiaattheTimeofHorpitalAdmissionAmericanJournaloftheMedicalSciences.2002;323:117{123.[17]JohnsonLB,BhanA,PawlakJ,ManzorO,SaravolatzLD.ChangingEpidemi-ologyofCommunity-OnsetMethicillin-ResistantStaphylococcusaureusBac-teremiaInfectionControlandHospitalEpidemiology.2003;24:431{435.[18]TambyahPA,HabibAG,NgT,GohH,KumarasigheG.Community-AcquiredMethicillin-ResistantStaphylcoccusaureusInfectioninSingaporeisusuallyHealthcareAssociatedInfectionControlandHospitalEpidemiology.2003;24:436{438.[19]HussainFM,Boyle-VavraS,DaumRS.Community-AcquiredMethicillin-ResistantStaphlyococcusaureusColonizationinHealthyChildrenAttendinganOutpatientPediatricClinicPediatricInfectiousDiseaseJournal.2001;20:763{767.[20]FergieJE,PurcellK.Community-AcquiredMethicillin-ResistantStaphylococcusaureusInfectionsinSouthTexasChildrenPediatricInfectiousDiseaseJournal.2001;20:860{863.[21]CampbellAL,BryantKA,StoverB,MarshallGS.EpidemiologyofMethicillin-ResistantStaphylococcusaureusataChildren'sHospitalInfectionControlandHospitalEpidemiology.2003;24:427{430.52

PAGE 60

[22]NakamuraMM,RohlingKL,ShashatyM,LuH,TangY,EdwardsKM.Preva-lenceofMethicillinResistantStaphylococcusaureusNasalCarriageintheCom-munityPediatricPopulationPediatricInfectiousDiseaseJournal.2002;21:917{921.[23]RathoreMH,KlineMW.Community-AcquiredMethicillin-ResistantStaphy-lococcusaureusInfectionsinChildrenPediatricInfectiousDiseaseJournal.1989;8:645{647.[24]FourPediatricDeathsfromCommunity-AcquiredMethicillin-ResistantStaphy-lococcusaureus{MinnesotaandNorthDakota,1997-1999MMWR.1999;48:707{710.[25]PublicHealthOutbreaks:OutbreaksofCommunity-AssociatedMethicillin-ResistantStaphylococcusaureusSkinInfections{LosAngelesCounty,California,2002{2003MMWR.2003;52:88.[26]JonesTF,KellumME,PorterSS,BellM,SchanerW.AnOutbreakofCommunity-AcquiredFoodborneIllnessCausedbyMethicillin-ResistantStaphy-lococcusaureusEmergingInfectiousDiseases.2002;8.[27]AbuduL,BlairI,FraiseA,ChengKK.Methicillin-ResistantStaphylococcusaureus:aCommunity-BasedPrevelanceSurveyEpidemiologyofInfections.2001;126:351{356.[28]GrundmannH,TamiA,HoriS,HalwaniM,SlackR.NottinghamStaphylococcusaureusPopulationStudy:PrevalenceofMRSAamongElderlyPeopleintheCommunityBMJ.2002;324:1365{1366.[29]MorinCA,HadlerJL.Population-BasedIncidenceandCharacteristicsofCommunity-OnsetStaphylococcusaureusInfectionswithBacteremiain4MetropolitanConnecticutAreas,1998JournalofInfectiousDiseases.2001;184:1029{1034.[30]SalmenlinnaS,LyytikainenO,Vuopio-VarkilaJ.Community-AcquiredMethicillin-ResistantStaphylcoccusaureus,FinlandEmergingInfectiousDis-eases.2002;18.[31]ShahinR,JohnsonIL,JamiesonF,McGreerA,TolinJ,Ford-JonesEL.Methicillin-ResistantStaphylococcusaureusCarriageinaChildCareCen-terFollowingaCaseofDiseaseArchivesofPediatricAdolescentMedicine.1999;153:864{868.[32]AdcockPM,PastorP,MedleyF,PattersonJE,MurphyTV.Methicillin-ResistantStaphylococcusaureusinTwoChildCareCentersJournalofInfectiousDiseases.1998;178:577{580.53

PAGE 61

[33]NaimiTS,LeDellKH,alDJBoxrud.EpidemiologyandClonalityofCommunity-AcquiredMethicillin-ResistantStaphylococcusaureusinMinnesota,1996-1998ClinicalInfectiousDiseases.2001;33:990{996.[34]FrankAL,MarcinakJF,alPDMangat.ClindamycinTreatmentofMethicillin-ResistantStaphylococcusaureusInfectionsinChildrenPediatricInfectiousDis-easeJournal.2002;21:530{534.[35]ChambersHF.TheChangingEpidemiologyofStaphylcoccusaureusEmergingInfectiousDiseases.2001;7:178{182.[36]MRSAsuperbug'carriedbypets'2003.54


xml version 1.0 encoding UTF-8 standalone no
record xmlns http:www.loc.govMARC21slim xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.loc.govstandardsmarcxmlschemaMARC21slim.xsd
leader nam Ka
controlfield tag 001 001469351
003 fts
006 m||||e|||d||||||||
007 cr mnu|||uuuuu
008 040524s2004 flu sbm s000|0 eng d
datafield ind1 8 ind2 024
subfield code a E14-SFE0000253
035
(OCoLC)55520417
9
AJR1105
b SE
040
FHM
c FHM
1 100
Kessler, Melissa Gail.
0 245
Risk factors for pediatric community-acquired methicillin-resistant Staphylococcus aureus
h [electronic resource] /
by Melissa Gail Kessler.
260
[Tampa, Fla.] :
University of South Florida,
2004.
502
Thesis (M.S.P.H.)--University of South Florida, 2004.
504
Includes bibliographical references.
516
Text (Electronic thesis) in PDF format.
538
System requirements: World Wide Web browser and PDF reader.
Mode of access: World Wide Web.
500
Title from PDF of title page.
Document formatted into pages; contains 61 pages.
520
ABSTRACT: Methicillin-Resistant Staphylococcus aureus (MRSA) began as a nosocomial infection due to overuse of antibiotics. Several previous studies have reported an increase in this infection in adult patients who have not been hospitalized. It has also been reported that there is an increase in MRSA in children. Some of these children became infected even though they were not at high risk for the infection. After approval from the All Children's Hospital Institutional Review Board (IRB), a cross sectional study was conducted with pediatric admissions and pediatric emergency room visits to determine the characteristics of Methicillin-Sensitive Staphylococcus aureus and MRSA. During this study, a review of 672 medical charts was conducted. The study participants ranged in age from newborns to 18 years of age. In order to be enrolled in the study, the subjects' cultures were collected either as outpatients or within 72 hours of admission. The data that was collected from each chart included age, race/ethnicity, gender, type of infection, preexisting medical conditions, and risk factors for infection. The potential risk factors include antibiotic use, previous surgery or outpatient procedure, previous MRSA infection, immunotherapy, community worn device, and residence in a facility. Statistical analysis was conducted using Epi Info and SAS software packages. In regards to demographic characteristics, black children are 2.98 times more likely to have an MRSA infection than white children. Gender and age were not risk factors for the development of the infection. The risk factors that were significant in whites were home health care (OR= 6.12, CI= 5.16, 7.08), community worn device (OR= 2.28, CI= 1.67, 2.89), previous hospitalization (OR= 2.43, CI= 1.95, 2.91), previous MRSA infection (OR= 3.69, CI= 2.90, 4.48), and previous surgery (OR= 2.02, CI= 1.51, 2.53). In blacks, females were more likely to have MRSA (OR= 2.57, CI= 1.73, 3.41). This finding may be due to the small sample size of black children in the study. Of the analyzed risk factors, home health care (OR= 2.95, CI= 1.11, 4.79), community worn device (OR= 2.85, CI= 1.71, 4.01), previous hospitalization (OR= 1.98, CI= 1.13, 2.83), previous surgery (OR= 2.79, CI= 1.79, 3.79), and previous antibiotic (OR= 5.60, CI= 4.66, 6.54) use were all significant risk factors in blacks. Effect modification was tested between race and all risk factors. Race was an effect modifier only for the risk factor of previous antibiotic use (pvalue =.02). Adjustment of confounding was performed for each race due to the presence of effect modification. After the adjustment for confounding in whites, only home health care (OR=4.37 CI= 1.55, 12.32), previous MRSA infection (OR= 2.86 CI= 1.16, 7.05), and previous hospitalization (OR= 2.00 CI= 1.14, 3.50) remained statistically significant. In blacks, after adjustment of confounding, only previous antibiotic use (OR= 5.13 CI= 1.75, 15.08) remained significant. Adjustment for confounding was also preformed on the total risk factors model. A dose response relationship was present with increasing risk factors present.
590
Co-adviser: Heather Stockwell
Co-adviser: Roger Sanderson
653
antibiotic resistance.
MRSA.
bacterial infections.
infection control.
hospital epidemiology.
690
Dissertations, Academic
z USF
x Public Health
Masters.
090
RA425
773
t USF Electronic Theses and Dissertations.
4 856
u http://digital.lib.usf.edu/?e14.253