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1、AntimicrobialAgentsMartinVotavaOlgaKroftováOverviewIfbacteriamakeitpastourimmunesystemandstartreproducinginsideourbodies,theycausedisease.Certainbacteriaproducechemicalsthatdamageordisablepartsofourbodies.Antibioticsworktokillbacteria.Antibioticsarespecifictocertainbacteriaanddisruptth
2、eirfunction.WhatisanAntibiotic?Anantibioticisaselectivepoison.Ithasbeenchosensothatitwillkillthedesiredbacteria,butnotthecellsinyourbody.Eachdifferenttypeofantibioticaffectsdifferentbacteriaindifferentways.Forexample,anantibioticmightinhibitabacteria'sabilitytoturnglucoseintoenergy,ort
3、hebacteria'sabilitytoconstructitscellwall.Thereforethebacteriadiesinsteadofreproducing.AntibioticsSubstancesproducedbyvariousspeciesofmicroorganisms:bacteria,fungi,actinomycetes-tosuppressthegrowthofothermicroorganismsandtodestroythem.TodaythetermATBextendstoincludesyntheticantibacteri
4、alagents:sulfonamidesandquinolones.HistoryTheGermanchemistPaulEhrlichdevelopedtheideaofselectivetoxicity:thatcertainchemicalsthatwouldbetoxictosomeorganisms,e.g.,infectiousbacteria,wouldbeharmlesstootherorganisms,e.g.,humans.In1928,SirAlexanderFleming,aScottishbiologist,observedthatPen
5、icilliumnotatum,acommonmold,haddestroyedstaphylococcusbacteriainculture.SirAlexanderFlemingFleming’sPetriDishZoneofInhibitionAroundthefungalcolonyisaclearzonewherenobacteriaaregrowingZoneofinhibitionduetothediffusionofasubstancewithantibioticpropertiesfromthefungusHistoryPenicillinwasi
6、solatedin1939,andin1944SelmanWaksmanandAlbertSchatz,Americanmicrobiologists,isolatedstreptomycinandanumberofotherantibioticsfromStreptomycesgriseus.Susceptibilityvs.ResistanceofmicroorganismstoAntimicrobialAgentsSuccessoftherapeuticoutcomedependson:AchievingconcentrationofATBatthesite
7、ofinfectionthatissufficienttoinhibitbacterialgrowth.Hostdefensesmaximallyeffective–MIeffectissufficient–bacteriostaticagents(slowproteinsynthesis,preventbacterialdivision)Hostdefensesimpaired-bactericidalagentsCompleteATB-mediatedkillingisnecessarySusceptibilityvs.Resistance(cont.)D