抗生素英文精品ANTIBIOTICS(33p)课件.ppt

ANTIBIOTICSFrom the Greek:anti-againstbios-lifeChemotherapyPaul EhrlichUse of chemical agent to kill bacteria and not harm the hostSearch for the“Magic bullet”Developed an arsenic compound that killed the bacteria that causes syphilisCompound was called salvarsan but was quite toxic to the hostAntibioticsNatural compounds produced by microorganisms that inhibit the growth of other microbesMajority of antibiotics come from Streptomyces bacteria and moldsOver 100 different antibioticsAntibiotics generally have two namesBrand name created by the drug companyGeneric name based on the chemical structure or class of antibioticsFamous penicillin picturePenicillinWonder drugKilled bacteria with few side effects on the patientSELECTIVE TOXICITYPenicillin was NOT the first anti-bacterial compoundPenicillin was the FIRST natural compound that kills bacteriaAntibioticNot made in the labSpectrum of ActivityBroad spectrum antibioticsEffect both G+and G-bacteriaTetracyclineNarrow spectrum antibioticsEffects fewer types of pathogensMore selective?Penicillin best against G+bacteriaHow do antibiotics work?Inhibition of protein synthesisBroad spectrum of activity all bacteria have to make proteinsDifference in ribosome size in bacteria accounts for selective toxicityChloramphenicol,erythromycin(G+),streptomycin,tetracyclinesInjury to plasma membraneChanges to permeability of membrane causes loss of metabolitesPolymyxin BInhibition of synthesis of essential metabolitesBlock enzyme activityCompetitive inhibition of enzyme activityPABA(para-aminobenzoic acid)competitionSulfonamidesCommonly used antibiotic typesPenicillinsCephalosporinsAnimoglycosidesMacolidesSulfonamidesFluoroquinolonesTetracyclinesPolypeptidesPenicillinDestroys the cell wall of bacteriaBest against G+bacteria during active growthExamples:Penicillin GPenicillin VAmpicillinAmoxicillinAminoglycosidesInhibition of protein synthesis in bacteriaSome toxic reactions possible in kidney and liverExamplesGentamicinStreptomycinNeomycinMacrolidesInterfere with bacterial protein synthesisCommonly given to patients that are sensitive to penicillinGastrointestinal discomfort is a common side effectExamplesAzithromycinErthromycinSulfonamidesVery early antimicrobial substance Commonly called sulfa drugsDeveloped in the 1930s in GermanyMode of action is enzyme inhibitionAllergy to sulfa is commonFluoroquinolonesLarge class of semi-synthetic broad spectrum antibioticsInhibition of bacterial DNA replicationFew side effects,well toleratedExamplesCiprofloxacinNorfloxacinTetracycline AntibioticsMembers of this group of antibiotics are produced by Streptomyces group of bacteriaInhibition of protein synthesisUsed commonly to treat acneExamplesTetracyclineDeoxycyclinePenicillinaseCephalosporin and PenicillinCephalosporinProduced from a fungusSimilar in action to penicillinMore active against G-bacteriaMore resistant to penicillinasePenicillinProduced from fungusInhibits cell wall synthesisEffective against mostly G+bacteriaPenicillinase sensitivityCephalosporin and PenicillinAntibiotic Resistance(A BIG problem)Resistance is acquired by mutationR(resistance)plasmids acquired by bacterial conjugationHow to limit resistanceTake all your pills,dont stop when you feel betterUse antibiotics only when necessaryNEVER take antibiotics for viral infection aloneNosocomial InfectionsInfections acquired while in a health care facilitiesCDC estimates 2 million people per year get these infections90,000 deaths per yearAntiviral DrugsLimited in numberTargets for these drugs are viral reproductionNucleotide analogs are the most commonly used agents disrupt viral nucleic acid replicationAcyclovirNucleotide analogSensitivity Testing