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1、AntimicrobialAgentsMartinVotavaOlgaKroftováOverviewIfbacteriamakeitpastourimmunesystemandstartreproducinginsideourbodies,theycausedisease.Certainbacteriaproducechemicalsthatdamageordisablepartsofourbodies.Antibioticsworktokillbacteria.Antibioticsares
2、pecifictocertainbacteriaanddisrupttheirfunction.WhatisanAntibiotic?Anantibioticisaselectivepoison.Ithasbeenchosensothatitwillkillthedesiredbacteria,butnotthecellsinyourbody.Eachdifferenttypeofantibioticaffectsdifferentbacteriaindifferentways.Forexamp
3、le,anantibioticmightinhibitabacteria'sabilitytoturnglucoseintoenergy,orthebacteria'sabilitytoconstructitscellwall.Thereforethebacteriadiesinsteadofreproducing.AntibioticsSubstancesproducedbyvariousspeciesofmicroorganisms:bacteria,fungi,actinomycetes-
4、tosuppressthegrowthofothermicroorganismsandtodestroythem.TodaythetermATBextendstoincludesyntheticantibacterialagents:sulfonamidesandquinolones.HistoryTheGermanchemistPaulEhrlichdevelopedtheideaofselectivetoxicity:thatcertainchemicalsthatwouldbetoxict
5、osomeorganisms,e.g.,infectiousbacteria,wouldbeharmlesstootherorganisms,e.g.,humans.In1928,SirAlexanderFleming,aScottishbiologist,observedthatPenicilliumnotatum,acommonmold,haddestroyedstaphylococcusbacteriainculture.SirAlexanderFlemingFleming’sPetriD
6、ishZoneofInhibitionAroundthefungalcolonyisaclearzonewherenobacteriaaregrowingZoneofinhibitionduetothediffusionofasubstancewithantibioticpropertiesfromthefungusHistoryPenicillinwasisolatedin1939,andin1944SelmanWaksmanandAlbertSchatz,Americanmicrobiolo
7、gists,isolatedstreptomycinandanumberofotherantibioticsfromStreptomycesgriseus.Susceptibilityvs.ResistanceofmicroorganismstoAntimicrobialAgentsSuccessoftherapeuticoutcomedependson:AchievingconcentrationofATBatthesiteofinfectionthatissufficienttoinhib
8、itbacterialgrowth.Hostdefensesmaximallyeffective–MIeffectissufficient–bacteriostaticagents(slowproteinsynthesis,preventbacterialdivision)Hostdefensesimpaired-bactericidalagentsCompleteATB-mediatedkillingisnecessarySusceptibilityvs.Resistance(cont.)D