antibiotics

antibiotics - A ntibioticsandResistance a. Keyplayers 2....

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Antibiotics and Resistance a. Key players 2. Paul Erlich- a. Wanted to find a “magic bullet”.  – Wanted to find something that would kill microbes and  not humans. B. a. Salvarsan-first microbial agent  – an arsenical containing compound which was effective  against syphilis. First chemotherapeutic agent 2. Alexander Fleming-discovered the first antibiotic (penicillin) in 1928. Naturally  occurring substance produced by fungus or other microbes  ( http://microblogology.com/blog/?p=13 ) a. Chain and Florey-followed through on Fleming’s findings to isolate and produce penicillin. a. Terms 3. Selective toxicity  – antibiotics cause greater harm to microorganisms than to human  host – Generally by interfering with biological structures or biochemical processes  co m mon to bacteria but not to humans 4. Theraputic index-  Toxicity of drug is expressed as therapeutic index – lowest dose  toxic to patient divided by dose typically used for treatment – High therapeutic index  = less toxic to patient 5. Half-life  – rate of elimination of drug from body expressed in half-life – time it takes  for the body to eliminate one half the original dose in serum – Half-life dictates  frequency of dosage 6. Drug co mbinations can result in: a. Antagonistic effects b. Synergistic effects c. Additive effects
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7. Innate or intrinsic resistance a. Mechanisms of action(Fig. 21.2) Differing antibiotics target different  components of microbes.  1.  Cell wall synthesis:  All of these antibiotics act by disrupting peptidoglycan synthesis in bacterial cell wall, therefore weakening cell wall. a. β lactam drugs (Table 21.1, Fig. 21.3, Fig.21.5, Fig. 21.6)- active against growing/dividing microorganisms . They bind and inactivate the transpeptidases used to create the peptidoglycan wall – The functional structure in penicillin that causes it to work. (transpeptidases are also called penicillin binding proteins) b. All have a β lactam ring structure (
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This note was uploaded on 03/28/2010 for the course MCRO 251 taught by Professor Lorrainecramer during the Fall '09 term at UNC.

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antibiotics - A ntibioticsandResistance a. Keyplayers 2....

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