Chapter 24 Outline

Chapter 24 Outline - Chapter 24 Antimicrobial Drugs...

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Chapter 24 Antimicrobial Drugs Introduction 24.1 The History and Properties of Antimicrobial Agents The History of Chemotherapy Originated with Paul Ehrlich Ehrlich originated the concept of selective toxicity He and Sahachiro Hata discovered the effectiveness of arsphenamine (Salvarsan) against the syphilis spirochete Prontosil was a red dye found to inhibit some gram-positive bacterial species Alexander Fleming’s Serendipitous Discovery of Penicillin Ushered in the Era of Antibiotics Penicillium mold produces a substance that kills gram-positive bacteria Antimicrobial Agents Have a Number of Important Properties Synthetic agents are made in a pharmaceutical lab Antibiotics are products of or derived from living microorganisms Semisynthetic drugs include synthetic and antibiotic elements Selective toxicity means that a drug should harm the pathogen but not the host The toxic dose of a drug is the concentration causing harm to the host The therapeutic dose is the concentration eliminating pathogens in the host Together, the toxic and therapeutic doses are used to formulate the chemotherapeutic index Drugs have a range if pathogens on which they will work (antimicrobial spectrum) Broad spectrum drugs affect many taxonomic groups, narrow spectrum drugs only a few pathogens 24.2 The Synthetic Antibacterial Agents Sulfanilamide and Other Sulfonamides Target Specific Metabolic Reactions Sulfonamides act on the synthesis of folic acid in bacteria They out compete essential folic acid components for binding sites in a bacterial enzyme, preventing nucleic acid synthesis and DNA replication They have a broad antimicrobial spectrum Drugs resistance has arisen because bacteria have mutated to take up folic acid from their surroundings Other Synthetic Antimicrobials Have Additional Bacterial Cell Targets Isoniazid interferes with cell wall synthesis in species of Mycobacterium Quinolones block DNA synthesis in bacteria 24.3 The Beta-Lactam Family of Antibiotics Penicillin Has Remained the Most Widely Used Antibiotic Penicillins are active against many gram-positive and some gram-negative bacteria
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This note was uploaded on 04/17/2009 for the course MIC 201 taught by Professor Lacroix during the Spring '08 term at Rhode Island.

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Chapter 24 Outline - Chapter 24 Antimicrobial Drugs...

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