1. Antibiotics BC Yang Antibiotics and vaccines are among the biggest medical advances since 1000. (Culver Pictures) For lecture only

2. A brief history of antibiotics 1495, mercury to treat syphilis. 1630, quinine (chinchona tree) for malarial fever by South American Indians. 1889, Buillemin defined antibiosis. 1910, Paul Ehrlich developed arsenical compound (Salvarsan) for syphilis, term: the chemical knife. 1929, Alexander Fleming found penicillin. 1935, Gerhard Domagk showed the value of sulfonamides. 1940, Ernst Chain and Howard Flory demonstrated the effect of penicillin. 1940-1970, then searching for new antibiotics ~ recent year: modifying old drugs, finding new discipline in antibacterial combats Early time in war: thanks penicillin, we can go home now Now a day……….Oh eh?! For lecture only BC Yang

3. Thanks to work by Alexander Fleming (1881- 1955), Howard Florey ( 1898-1968) and Ernst Chain (1906-1979), penicillin was first produced on a large scale for human use in 1943. At this time, the development of a pill that could reliably kill bacteria was a remarkable development and many lives were saved during World War II because this medication was available. E. ChainH. FloreyA. Fleming For lecture only BC Yang

4. A tale by A. Fleming He took a sample of the mold from the contaminated plate. He found that it was from the penicillium family, later specified as Penicillium notatum. Fleming presented his findings in 1929, but they raised little interest. He published a report on penicillin and its potential uses in the British Journal of Experimental Pathology. For lecture only BC Yang

5. Scenario of penicillin action on E. coli 12 3 4 5 6 1: ordinary appearance 2-4: globular extrusions emerge 5: rabbit-ear forms 6: Ghost form For lecture only BC Yang

6. Natural products, including: toxins, antibiotics (about 70% of all known antibiotics), antifungals, etc, have historically been isolated and characterized from heterotrophic bacteria (e.g. Streptomyces). This was primarily due to the ease with which these organisms can be grown and manipulated in the laboratory. For lecture only BC Yang

7. In 2001, the problem of antimicrobial resistance posed a global threat to the effective treatment of many bacterial diseases. In developed countries, as many as 60% of hospital-acquired infections are caused by drug-resistant microbes. These infections are no longer found only in hospital or nursing home wards but are active in the community at large. Evaluation by BUSINESS COMMUNICATIONS COMPANY, INC., For lecture only BC Yang

8. An ideal antibiotics Broad-spectrum Did not induce resistance Selective toxicity, low side effects Preserve normal microbial flora For lecture only BC Yang

9. Susceptibility test Tube dilution method Minimal inhibitory concentration (MIC): the smallest amount of chemotherapeutic agent required to inhibit the growth of organism in vitro Disk diffusion method Zone of inhibition (ZOI): the correlation of ZOI and MIC has been established by FAD ETest. This commercially-prepared strip creates a gradient of antibiotic concentration when placed on an agar plate For lecture only BC Yang

10. Guidance of antimicrobial therapy Minimum inhibitory concentration: lowest concentration of antibiotic that inhibits visible growth Minimum bactericidal concentration: lowest concentration of antibiotic that kills 99.9% of the inoculum Serum bactericidal title: dilution of serum that kills 99.9% of the inoculum Synergy test: synergistic activity of multiple antibiotics For lecture only BC Yang

11. Use of antibiotics; is it properly applied? Acute infections in outpatients Acute infections in hospitalized patients Chronic infection (tuberculosis, AIDS) Agriculture/veterinary medicine For lecture only BC Yang

12. In vitro: Factors for optimal antibiotic action pH of environment: Nitrofurantoin is more active in acid pH; sulfonamides and aminoglycoside are more active in alkaline pH. Components of medium: Anionic detergents inhibit aminoglycosides, serum proteins bind to penicillin in varying degrees. Stability of drug: Aminoglycosides and chloramphenical are stable for long period in vivo. Size of inoculums: The larger the bacterial inoculum, the greater the chance for resistnat mutant to emerge. Metablic activity of microorganisms: Actively and rapidly growing organisms are more susceptible to drug action For lecture only BC Yang

13. Affecting factors in vivo Abscess: circulation is blocked off. Foreign bodies: obstruction of the urinary, biliary or respiratory tracts etc. Immunity. For lecture only BC Yang

14. Diagrammatic representation of the results of treatment related to specific chemotherapy Patients with normal immunity and uncomplicated mild to moderate infections Patients with serious life- threatening infections For lecture only BC Yang

15. Sites of action For lecture only BC Yang

16. Modes of action (1) Inhibitors of cell wall synthesis. Penicillins, cephalosporin, bacitracin, carbapenems and vancomycin. Inhibitors of Cell Membrane. Polyenes - Amphotericin B, nystatin, and condicidin. Imidazole - Miconazole, ketoconazole and clotrimazole. Polymixin E and B. Inhibitors of Protein Synthesis. Aminoglycosides - Streptomycin, gentamicin, neomycin and kanamycin. Tetracyclines - Chlortetracycline, oxytetracycline, doxycycline and minocycline. Erythromycin, lincomycin, chloramphenicol and clindamycin. Amphotericin Tetracyclines Aminoglycosides vancomycin For lecture only BC Yang

17. Modes of action (2) Inhibitors of metabolites (Antimetabolites). Sulfonamides - Sulfanilamide, sulfadiazine silver and sulfamethoxazole. Trimethoprim, ethambutol, isoniazid. Inhibitors of nucleic acids (DNA/RNA polymerase). Quinolones - Nalidixic acid, norfloxacin and ciprofloxacin. Rifamycin and flucytosine. rifamycin For lecture only BC Yang

18. Penicillin: an extensively studied example For lecture only BC Yang

19. Action mechanism of penicillin Action target: cell wall on penicillin binding proteins (PBPs) Transpeptidases (form cross-links in peptidoglycan) Beta-lactam ring attached to 5-membered thiazolidine ring Accessibility of PBPs differ in gram+ and gram- bacteria Amino acyl side chain groups determine spectrum, adsorption, susceptibility to lactamase Bactericidal inhibitors For lecture only BC Yang

20. Pharmacokinetics of penicillins Adsorption: can be oral Stability in acid condition:  PenG (no)  Pen V (yes)  Ampicillin (yes) Distribution: to most body sites; not in CSF unless inframmed meninges Excretion: rapid eliminated by renal secretion  Amoxacillin (yes)  Nafcillin (yes)  Peperacillin (no) For lecture only BC Yang

21. Clinical status of Penicillins Pen G (Pen V): natural Common strptococci (S. pneumoniae; S. pyrogenes); URTI, pneumonia meningitis, prophylaxis of rheumatic fever Nafcillin: penicillinase-resistant Staphylococci epidemic; bacteremia, septiemia Ampicillin: Gram- spectrum: E. coli; H. influenzae;Salmonella, shigella pharngitis, otitis media, UTI, gastroenteritis Peperacillin: Expanded spectrum/antipsuedomonal, enteric bacilli; Systemic infection in hospitalized patients (gram-, P aeruginoma) Combinations with  -lactamase inhibitors: URTI, pneumonias, meningitis, bactermia For lecture only BC Yang

22. Resistance B-lactamase Types: Different substrate specificity Penicillinases cephalosporinases Location: Gram+: extracellularly Gram-: periplasmic space Serine-  -Lactamase Metallo-  -Lactamase By Dr. Osnat Herzberg University of Maryland Biotechnology Institute (UMBI) Failure to bind to PBPs Cannot penetrate porins (gram-) Production of lactamase (penicillinase) Lack autolytic enzyme For lecture only BC Yang

23. Adverse effects Wickens K, Pearce N, Crane J, Beasley R. Antibiotic use in early childhood and the development of asthma. Clin Exp Allergy 1999;29:766-771. Thrombophlebitis Allergic reactions Superinfections (diarrhea) Seizures (rare) For lecture only BC Yang

24. Before on antibiotics: –Antibiotics act as powerful selective factors in the emergence and spread of resistant microoraganism. For lecture only BC Yang

25. 聯合報 八十五年 四月十三日 頭版新聞 In Rwanda For lecture only BC Yang

26. 1953: Shigella outbreak in Japan, multiple drug resistance 1950: M tuberculosis largely resistant to streptomycin For lecture only BC Yang

27. Resistances Natural (inherent) resistance  Structural barrel  Lack of target  Transport system Acquired resistance  Mutation  Gene exchange (conjugation in most) For lecture only BC Yang

28. Transferable antibiotic resistance in bacteria Reduced uptake into cell (chloramphenicol) Active efflux from cell (tetracycline) Modification of antibiotic targets (  -lactam, erythromycin) inactivation of antibiotic by anzymic modification: hydrolysis (  -lactam, erythromycin ); derivatization (aminoglycosides) Sequestration of antibiotic by protein binding (  - lactam) Metabolic bypass (sulfonamides) Overproduction of antibiotic target (titration: sulfonamides) For lecture only BC Yang

29. Spread of resistance In most: Day-care, nursing homes, correctional facilities Sanitation, animal feeds (fecal-oral) Sexual/ Respiratory transmission International travel Immunosuppression For lecture only BC Yang

30. Some probable overuse/misuse of antibiotics Prophylatic use before surgery Empiric use (blinded use) Increased use of broad spectrum agents Pediatric use for viral infections Patients who do not complete course (chronic disease, eg. TB, AIDS) Antibiotics in animal feeds For lecture only BC Yang

31. Policy to deal drug resistance (1) Ideally, bacteriological management of clinical infection should involve: 1. Identification of causative organism 2. Sensitivity test 3. Follow-up the drug effect 4. Monitor antibiotic level to avoid toxicity. In reality, most patients requiring antimicrobial therapy are treated empirically. In serious infections immediate chemotherapy may be life-saving. For lecture only BC Yang

32. Policy to deal drug resistance (2) Periodic changes of antibiotics used might change selective pressure and thus avoid the emergence of resistance and retain the therapeutic value of antibiotics over a longer period. The unnecessary prophylactic or animal feeds use should be discouraged. Distribution of information on current/updated infectious microbes (consult microbiologists): use more targeted antibiotics Patient education ( 不隨便吃藥, 停藥 ) For lecture only BC Yang

33. New antibiotics development Pharmaceutical industry putting resources back into discovery Liaisons with university researches Discoveries in microbial physiology and genetics offering new targets, new disciplines Combinational chemistry (mass screening) For lecture only BC Yang