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ID:20199595
大小:680.00 KB
页数:52页
时间:2018-10-09
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1、CHAPTER35ANTIBIOTICSJihongYaoIntroductionPharmacologicaleffects,Clinicaluses,untowardeffectofPenicillinG;PharmacolgicaleffectsofbroadspectrumPenicillinsandpenicillinase-resistantPenicillins;Spectrumofactivity,clinicaluseanduntowardeffectsofcephalosporins;Pharmacologicaleffects
2、andclinicaluseoferythromycin;Spectrumofactivity,clinicaluseanduntowardeffectsofAminoglycosides,TetracyclinesandChloramphenicols.Whatisantibiotics?Antibioticsaresolublecompoundsthatarederivedfromcertainmicroorganismsandthatinhibitthegrowthofothermicroorganisms.Beta-lactamantibio
3、tics(Beta内酰胺类抗生素)Beta-lactamantibioticscontainaBeta-lactamringinstructurewhichincludepenicillinsandcephalosporins.ThepenicillinsandcephalosporinsdifferinthatThenucleusofpenicillins6-aminopenicillanicacid(6-APA,6-氨基青霉烷酸)Thenucleusofcephalosporins7-aminocephalosporanicacid(7-ACA,
4、7-氨基头孢烷酸).StructureofpenicillinsandproductsoftheirenzymatichydrolysisPenicillinG(青霉素G)SpectrumofactivityofpenicillinGThepenicillin-susceptibleorganismsarenonpenicillinase-producingstrainsofmostgram-positiveandgram-negativecocci,gram-positivebacilli,andspirochetes.Mechanismofact
5、ionofpenicillinGPenicillinsinhibittheformationofcellwallandarebactericidalinaction.Penicillinexertsitseffectbybindingtocellularreceptorsnowidentifiedastranspeptidationenzymeswhichcatalyzedthecross-linkingreactionofcellwall.Bybindingtoandinhibitingtranspeptidationreactions,itint
6、erruptsthesynthesisofcellwallpeptidoglycan.Adefectivecellwallallowswatertoenterandswellthecell,causingmembranelysisandcelldeath.NotesTheactiondoesnotoccurredinmanoranimalswhodonotpossesthecellwallsurroundingthecellmembrane.Sincepenicillinspreventnewcross-linksduringtheformation
7、ofcellwallsanddonotdisruptestablishedcross-links,theyinterfereonlywithgrowingnotrestingcells.Penicillininsensitivebacteriahavestructurallydifferentcellwalls(containlesspeptidoglycan)suchasgram-negativebacilli.BacterialresistanceofPenicillinGPenicillinaseisabeta-lactamasewhichhy
8、drolyzesthebeta-lactamringofpenicillintoformpenicilloi
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