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23 Cards in this Set
- Front
- Back
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Selective Toxicity: |
toxic to bacteria, not bad for us based on differences in physiology between us and bacteria |
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What is optimal for a medically useful antibiotic? |
high therapeutic index-low MIC |
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MIC stands for? |
Minimum Inhibitory Concentration |
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Irreversible killing of bacteria |
bactericidal |
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bacteriostatic: |
stops growth (reversible) |
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In regards to antibiotics what factors or adsorption and distribution in the body need to be considered?
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penetration to relevant site
rate of excretion rate of metabolism |
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If you wanted to isolate a derivative of your favorite bacterial strain that was antibiotic resistant, and you could not use genetic exchange, which of the following antibiotics could you use? |
(spontaneous point mutations) nalidixic acid rifampin streptomycin |
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If you wanted to use an antibiotic resistance gene cassette to label a mutation that you made or to increase the usefulness of a plasmid, which of the following antibiotics would you use? |
(need to add to a specific gene) ampicillin chloramphenicol tetracycline |
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Beta lactams: |
inhibit transpeptidation (D-Ala-D-Ala) penicillins cephalosporins |
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Vancomycin: |
inhibits transpeptidation and transport, interferes with enzymes |
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Bacitracin: |
transport of the subunits across membrane |
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gram-positive resistance to? |
polymyxin |
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wall-less bacteria is resistant to? |
cephalosporin |
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aerobes are resistant to? |
metronidazole |
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gram-negative bacteria are resistant to? |
vancomycin |
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List the antibiotics that effect protein synthesis by acting at the ribosome? |
ahminoglycosides gentamicin neomycin streptomycin tetracyclines chloromphenical erythromycin |
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List the antibiotics that inhibit DNA synthesis: |
quinolones inhibit gyrate (nalidixic acid) metronidazole disrupts DNA after reduction in anaerobes |
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List the antibiotics that disrupt RNA synthesis: |
Rifampin |
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List the antibiotics that are metabolic inhibitors and what exactly they do: |
sulfonamides (PABA analogs bloc dihyropeteroate synthesis) trimethoprim (blocks dihydrofolate reductase) |
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List the general mechanisms of resistance (4) |
enzymatically modify or degrade antibiotic B-lactamase (bla) chloramphenicol acetyl transferase (cat) aminoglycoside phosphotransferase (app) |
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What are some examples of altering the target to the antibiotic? |
spontaneous mutation enzymatic modification (erythromycin) new biosynthetic pathway yielding altered target (vancomycin) acquire new enzymes that are resistant |
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Antibiotic resistance plasmid: |
new enzyme to modify/pump antibiotic new enzyme to modify target new biosynthetic pathway or target |
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Chromosomal point mutation: |
target changed not recognized by antibiotic retains cellular function |
