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22 Cards in this Set
- Front
- Back
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What are Chemotherapeutic agents?
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- control microbial growth internally
- can be synthetic or produced by microbes (antibiotics) |
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What is a therapeutic ratio
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- highest dose that will control infection and patient can tolerate without toxic effects
- ideal antibiotic has high therapeutic ratio |
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How do antibiotics work?
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- exploit differences between prokaryotic/eukaryotic microbes and mammalian cells:
- bacteria - fungal cell walls - Prokaryotic ribosomes - RNA polymerases |
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Chemotherapeutic Agents - Growth Factor Analogs
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- chemical similar in structure to essential growth factor
- blocks utilization of growth factor - Sulfa drugs - first synthetic antibiotics - Similar to folic acid - precursor to nucleic acid |
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Chemotherapeutic Agents - Base Analogs
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- Substituted base analogs are effective anti-virals and anti-fungals
- Inhibit DNA replication and RNA transcription |
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What effect do common Chemotherapeutic agents have on cells?
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- Inhibit baterial cell wall synthesis
- Prevent cross-linkage of NAM subunits - results in weakened cell walls and eventually lysis |
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Penicillin and derivitives make up what portion of all antibiotics?
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- over half!
- All contain the B-lactam ring - bacterial B-lactamases target this ring to inactivate the antibiotic |
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Types of Penicillin derivatives?
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- Semisynthetic derivatives of B-lactams
- Stable; readily absorbed; less susceptible; more active - Monobactams - Only effective against aerobic Gram-bacteria - Cephalosporins -ceftriaxone - Used against N.gonorrhoeae |
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What are some other cell wall-disrupting antibiotics?
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- Vancomycin
- Bacitracin - Isoniazid and ethambutol |
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How do inhibitors of protein synthesis work?
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- exploit differences in ribosomes and target translation
- Prokaryotic ribosomes are 70S - Eukaryotic ribosomes are 80S - Mitochondria of animals and humans contain 70S ribosomes; can be harmed by these antibiotics |
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What are Aminoglycosides?
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- Bacteria-produced antibiotics
- Streptomycin; kanamycin; gentamicin; neomycin - alters shape of 30S subunit - effective against Gram negative bacteria - primarily used as reserve antibiotics when others fail |
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What are Macrolides?
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- Bacteria-produced antibiotics: lactone rings connected to sugars
- Erythromycin; oleandromycin; spiramycin; tylosin - inhibit translation elongation at 50S - erythromycin used when patients are allergic to penicillins |
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What are tetracyclines?
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- Bacteria-produced broad-spectrum antibiotics
- naphthacene ring system - can substitute at several positions to form new antibiotics - inhibits translation elongation at 30S subunit |
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What are polyenes?
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- Anti-fungal drugs
- bings/targets ergosterol - makes holes in membranes - can cause toxicity; liver and kidney damage - fungi are eukaryotic microbes and are hard to target without harming human cells |
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What are Azoles?
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- Anti-fungal drugs
- effects membrane by inhibiting ergosterol synthesis - fluconazole (Diflucan) - intraconazole |
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What are Allyamines?
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- Anti-fungal drugs
- effects membranes - terbinafine (Lamisil) |
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What are Echinocandins?
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- Anti-fungal drugs
- effects cell wall - caspofungin (Cancidas) |
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What are the types of Anti-Fungal Drugs?
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- Polyenes
- Azoles - Allyamines - Echinocandins |
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Why do anti-viral drugs also affect host cells?
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- Viruses use host cell machinery to grow and reproduce within host cells
- anti-viral drugs also effect host cells producing serious side-effects |
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What causes antibiotic resistance?
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- resistance is correlated with inappropriate, extensive use of antibiotics and inadequate dosage or time of administration
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What are some mechanisms of Antibiotic Resistance?
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- Reduced permeability
- Inactivation of the antibiotic - Alteration of the target - Development of resistant pathway - Efflux (pumping out of cell) |
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How are new anti-microbial drugs developed?
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- Analogs of existing drugs
- modify structures to improve potency, solubility, etc - Computer-based design creates and tests new molecules |
