抗生素英文——Discovery-of-Antimicrobial-Drugs.ppt

,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Game plan,Lecture,Antibiotics,Antibiotic resistance,Gene transfer,Transformation,Transduction,Conjugation,Extra credit assignment,Lab,Lab Exam,Pre-lab,Transformation,-1928,:Fleming discovered penicillin,produced by,Penicillium,Discovery of Antimicrobial Drugs,Figure 1.5,Where to antimicrobials come from?,Broad spectrum,-affect a broad range of gram-positive and gram-negative bacteria,Narrow spectrum,-affects a narrow range of bacteria,Spectrum of activity,The Action of Antimicrobial Drugs,Figure 20.2,Case study in narrow spectrum antibiotics:Penicillin,-Natural penicillins,-Semisynthetic penicillins,Figure 20.7,Penicillin retention,Resistance to Antibiotics,Figure 20.20,Enzymatic destruction of drug,Prevention of penetration of drug,Alteration of drugs target site,Rapid ejection of the drug,Figure 20.8,A peek at antibiotic resistance penicillinase,-A variety of mutations can lead to antibiotic resistance,-Misuse of antibiotics selects for resistance mutants.Misuse includes:,Using outdated or weakened antibiotics,Using antibiotics for the common cold and other inappropriate conditions,Using antibiotics in animal feed,Failing complete the prescribed regimen,Using someone elses leftover prescription,-Resistance genes are often on plasmids or transposons that can be transferred between bacteria,Mechanisms of resistance,How was NDM-1 tranfered?,Vertical gene,transfer,Horizontal gene,transfer,All transfer methods rely on recombination,Figure 8.22,Horizontal gene transfer:,Transformation,1920s-Griffith experiment,Horizontal gene transfer:,Transformation,1920s-Griffith experiment,Horizontal gene transfer:,Transformation,DNA:,Cell free or“naked”DNA,Requirements:,Competent cells,Recombination,Horizontal gene transfer:,Transduction,Demo,(generalized,specialized),Horizontal gene transfer:,Generalized transduction,DNA type:,Small chromosomal,fragments from,bacteria,Requirements:,Lytic phage,Recombination,Horizontal gene transfer:,Transduction,Horizontal gene transfer:,Conjugation,Demo,(F factor),Horizontal gene transfer:,Conjugation,DNA type:,F plasmid,Requirements:,F+cell,F cell,Sex pili/cell surface,molecules,Horizontal gene transfer compared,Independent Study,Study for Exam 2!,