Antibiotic susceptibility of Aggregatibacter actinomycetemcomitans JP2 in a biofilm

摘要

Background:Localizedaggressiveperiodontitis(LAgP)isaninflammatorydiseaseassociatedwithspecificbacteria,particularlyAggregatibacteractinomycetemcomitans,whichcanresultinearlytoothloss.Thebacteriagrowasabiofilmknownassubgingivalplaque.Treatmentincludesmechanicaldebridementofthebiofilm,oftenassociatedwithempiricalantibiotictreatment.Objective:TheaimsofthisstudyweretotestinvitrothesensitivityofA.actinomycetemcomitansJP2duringplanktonicandbiofilmgrowthtodoxycyclineandtothecombinationofmetronidazoleandamoxicillin,whicharetwoantibioticprotocolscommonlyusedinclinicalpractice.Design:Twoinvitrobiofilmmodelswereusedtotesttheeffectsoftheantibiotics:astatic96-wellplateassaywasusedtoinvestigatetheeffectoftheseantibioticsonbiofilmformationwhilstaflowchambermodelwasusedtoexaminetheeffectonestablishedbiofilms.Results:Oftheantibioticstestedinthismodelsystem,doxycyclinewasmostefficaciouswithaminimalinhibitoryconcentration(MIC)againstplanktoniccellsof0.21mg/Landminimalbiofilminhibitoryconcentration(MBIC)of2.10mg/L.Themostcommonlyprescribedantibioticregimen,amoxicillinmetronidazole,wasmuchlesseffectiveagainstbothplanktonicandbiofilmcellswithanMICandMBICof12.0mg/Land20.2mg/L,respectively.Asingletreatmentoftheclinicallyachievableconcentrationof10mg/LdoxycyclinetosparseA.actinomycetemcomitansbiofilmsintheflowchambermodelresultedinsignificantdecreasesinbiofilmthickness,biovolume,andcellviability.DenseA.actinomycetemcomitansbiofilmsweresignificantlymoreresistanttodoxycyclinetreatment.Lowconcentrationsofantibioticsenhancedbiofilmformation.Conclusion:A.actinomycetemcomitansJP2homotypicbiofilmsweremoresusceptibleinvitrotodoxycyclinethanamoxicillinmetronidazole.Keywords:Localizedaggressiveperiodontitis;Aggregatibacteractinomycetemcomitans;doxycycline;metronidazole;biofilm(Published:8May2013)Citation:JournalofOralMicrobiology2013,5:20320-http://dx.doi.org/10.3402/jom.v5i0.20320