Low-Dose Infectivity of Staphylococcus aureus (SMH Strain) in Traumatized Rat Tibiae Provides a Model for Studying Early Events in Contaminated Bone Injuries

摘要

Animalmodelsofpost-traumaticacuteosteomyelitis(OM)thatcloselymimichumanscenarios,includinginfectionprophylacticproceduressuchasdebridementandlavage,mayprovideabetterunderstandingofOM.Wecontaminatedmechanicallytraumatizedrattibiae(n=69)withvariousdosesofaStaphylococcusaureusstrain(SMH)knowntocausehumanOMandthenperformedcurettageandlavage.Tibiaewereharvested24hafterlavageforassessmentofbacterialloadanddeterminationofminimalinfectivedosesfor50%(IDsubxmlns="http://pub2web.metastore.ingenta.coms/"50/sub)and95%(IDsubxmlns="http://pub2web.metastore.ingenta.coms/"95/sub)ofrats.Someexperimentsvariedtibialharvesttimeafterlavage(n=10);forprogressiveinfection,tibiaewereevaluatedat7and15daysaftercontamination(n=17foreachtimepoint).At24haftercontamination,theIDsubxmlns="http://pub2web.metastore.ingenta.coms/"50/subwas1.8×10supxmlns="http://pub2web.metastore.ingenta.coms/"3/supCFU,andtheIDsubxmlns="http://pub2web.metastore.ingenta.coms/"95/subwas9.2×10supxmlns="http://pub2web.metastore.ingenta.coms/"3/supCFU.TibialbacterialloadsdidnotincreasewithinoculagreaterthantheIDsubxmlns="http://pub2web.metastore.ingenta.coms/"95/sub.Lavageremovedmanybacteriafrombone,butitdidnotpreventsubsequentinfectionordisease.At15daysaftercontamination,mosttibiae(14of17)wereinfected,withmacroscopicandradiologicalsignsofestablishedOM.ThisnewlydescribedratOMmodel,withalowIDsubxmlns="http://pub2web.metastore.ingenta.coms/"95/subdespiteprophylacticcurettageandlavage,closelymimicseventsincontaminatedhumanboneinjuries.Thissituationwillallowstudyofearlyfactorsincontaminatedboneinjuries,includingclinicalinterventionsthatmayreduceinfectionandpreventdisease.