抗生素与细胞膜(英文)Antibiotics-and-cell-envelope.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,1,Dr.Alvin Fox,Antibiotics:cell envelope,Lecture 36,2,Key Words,Sterilization/disinfection/antisepsis,Beta lactam,Antibiotic,Penicillins,Selective toxicity,Cephalosporins/cephamycins,Bactericidal,Monobactam,Bacteriostatic,Clavulinic acid,Minimal inhibitory concentration(MIC),Penicillinase/beta lactamase,Susceptibility testing,Polymyxin B,Penicillin binding proteins,Daptomycin,Autolysins,Isoniazid,Cycloserine,Ethioniamide,Bacitracin,Ethambutol,Vancomycin,Resistance,3,STERILIZATION,All killed,non-selective,4,Sterilization,autoclaving,121,o,C(heat/pressure),Heat resistant materials,ethylene oxide,non heat resistant,Usually equipment,being replaced e.g.H,2,O,2,/free radicals,ultra-violet light,surfaces(e.g.operating rooms),not totally effective,gamma radiation,mainly food industry,6,Disinfection,Liquids that kill bacteria,e.g.phenol based,too toxic for skin surfaces,7,Antiseptics,Topical(e.g.skin),e.g.iodine or 70%alcohol,“reduce”bacterial load,8,ANTIBIOTICS,Selectively toxic for bacteria,bactericidal(killing),bacteriostatic(growth inhibition),minimize harm to patient,10,Antibiotics work together,with the immune system,11,Minimal inhibitory concentration,lowest level stopping growth,e.g.zone of inhibition around a disk impregnated with antibiotic,13,Cross-linking of peptidoglycan,Old,New,15,Cycloserine,X,Cytoplasm,sugar,amino,acid,X,X,X,alanine(ala)analog,-inhibits conversion L-ala to D-ala,-inhibits formation of D-ala-D-ala,16,Bacitracin,Inhibits dephosphorylation,18,TRANSPORT OF PEPTIGOGLYCAN SUBUNIT ACROSS MEMBRANE,Cell membrane,undecaprenol,P,P,Cell wall,19,TRANSPORT OF PEPTIGOGLYCAN SUBUNIT ACROSS MEMBRANE,Cell membrane,undecaprenol,P,P,Cell wall,20,TRANSPORT OF PEPTIGOGLYCAN SUBUNIT ACROSS MEMBRANE,Cell membrane,undecaprenol,P,P,Cell wall,21,TRANSPORT OF PEPTIGOGLYCAN SUBUNIT ACROSS MEMBRANE,Cell membrane,undecaprenol,P,P,Cell wall,22,MINUS,BACITRACIN,Cell,membrane,undecaprenol,P,Cell wall,TRANSPORT OF,PEPTIGOGLYCAN SUBUNIT,ACROSS MEMBRANE,24,Vancomycin,Cell wall,binds to D-ala-D-ala,inhibits cross-linking,Vancomycin,25,Beta lactam antibiotics,penicillins,Cephalosporins/cephamycins,monobactams,26,lactams,Cell wall,Penicillin binding protein,inhibit penicillin binding proteins,stop cross-linking,lactam,Active site,of enzyme,28,Attached to lactam ring,penicillins,5 membered ring,Cephalosporins/cephamycins,6 membered ring,monobactams,no second ring,29,Chemical modifications change biological activity,Early lactam antibiotics,inactive against Gram negative bacteria,no penetration of outer membrane,31,lactam,binds strongly to,lactamases,inhibits activity,limited potency as antibiotic,used in conjunction with other,lactams,Clavulinic acid,32,Polymyxin B,binds,lipid A,phospholipids,disrupts outer membrane,Gram negative bacteria,toxic to human cells,Daptomycin,33,Causes depolarization of bacterial cell membrane,34,Isoniazid and Ethionamide,-chemically related,-,blocks mycolic acid synthesis,Ethambutol,blocks arabinogalactan synthesis,Cycloserine,Anti-tuberculosis drugs,