100L-F09_WEEK%208_Medical%20and%20food%20microbiology

100L-F09_WEEK%208_Medical%20and%20food%20microbiology -...

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rinciples of Antimicrobial Therapy Principles of Antimicrobial Therapy oal of antimicrobial chemotherapy: Goal of antimicrobial chemotherapy: administer a drug to an infected person, which destroys the infective agent without harming the host’s cells Rather difficult to achieve this goal Chemotherapeutic agents described with regard to their origin, range of effectiveness, and whether they are naturally produced or chemically synthesized
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e Origins of Antimicrobial Drugs The Origins of Antimicrobial Drugs ntibioitics are common metabolic products Antibioitics are common metabolic products of aerobic bacteria and fungi Bacteria: Streptomyces and Bacillus Molds: Penicillium and Cephalosporium Chemists have created new drugs by altering the structure of naturally occurring antibiotics Also Searching for metabolic compounds with antimicrobial effects in species other than bacteria and fungi
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teractions Between Drug and Microbe Interactions Between Drug and Microbe Goal of antimicrobial drugs Disrupt the cell processes or structures of bacteria, fungi, and protozoa Or inhibit virus replication Most interfere with the function of enzymes required to synthesize or assemble macromolecules or destroy structures already formed in the cell Drugs should be selectively toxic they kill or inhibit microbial cells without damaging host tissues
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echanisms of Drug Action Mechanisms of Drug Action Inhibition of cell wall synthesis Inhibition of nucleic acid structure and function Inhibition of protein synthesis Interference with cell membrane structure or function hibition of folic acid synthesis Inhibition of folic acid synthesis
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Antimicrobial Drugs that Affect the Bacterial Cell Wall Active cells must constantly synthesize new peptidoglycan and transport it to the proper place in the cell envelope Penicillins and cephalosporins react with one or more of the enzymes required to complete this process Bactericidal antibiotics
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Antimicrobial Drugs that Affect Nucleic Acid Synthesis lock synthesis of nucleotides Block synthesis of nucleotides Inhibit replication Stop transcription Inhibit DNA synthesis
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ntimicrobial Drugs that Block Protein Synthesis Antimicrobial Drugs that Block Protein Synthesis Inhibit translation by reacting with the ribosome mRNA complex Prokaryotic ribosomes are different from eukaryotic ribosomes selective
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Antimicrobial Drugs that Disrupt Cell Membrane Function Damaged membrane invariably results in death from disruption in metabolism or lysis Specificity for particular microbial groups based on differences in the types of lipids in their cell membranes
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Antimicrobial Drugs that Inhibit Folic Acid Synthesis l f i d d ti th i titi Sulfonamides and trimethoprim competitive inhibition Supplied to cells in high concentrations to make sure enzyme is constantly occupied with the metabolic analog rather than the true substrate
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This note was uploaded on 11/25/2009 for the course MIMG 100L taught by Professor L during the Fall '09 term at UCLA.

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100L-F09_WEEK%208_Medical%20and%20food%20microbiology -...

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