Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case M I C R O B I O L O G Y a n i n t r o d u c t i o n ninth edition TORTORA  FUNKE  CASE Part A 20 Antimicrobial Drugs

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antimicrobial Drugs  Chemotherapy: The use of drugs to treat a disease.  Antimicrobial drugs: Interfere with the growth of microbes within a host.  Antibiotic: A substance produced by a microbe that, in small amounts, inhibits another microbe.  Selective toxicity: A drug that kills harmful microbes without damaging the host.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  1928: Fleming discovered penicillin, produced by Penicillium.  1940: first clinical trials of penicillin.  Antibiosis Figure 20.1 Photograph by Fleming, 1928

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 20.2 Narrow and Broad Spectrums of Microbial Activity

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Action of Antimicrobial Drugs  Broad-spectrum  Superinfection  2 Types of Antimicrobial drugs:  Bactericidal  Bacteriostatic

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis  Penicillin  Group of over 50 chemically related antibiotics  Natural penicillins  Semisynthetic penicillins

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Penicillins Figure 20.6

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis  Penicillin  Penicillinase-resistant penicillins  Methicillin – the 1 st penicillinase-resistant

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis  Polypeptide antibiotics  Bacitracin  Topical application  Against gram-positives  Vancomycin  Important "last line" against antibiotic resistant S. aureus

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antibacterial Antibiotics Injury to the Plasma Membrane  Polymyxin B  Topical  Combined with bacitracin and neomycin in over-the-counter preparation.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antibacterial Antibiotics Competitive Inhibitors  Sulfonamides (sulfa drugs)  Inhibit folic acid synthesis  Broad spectrum Figure 5.7