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22 Cards in this Set

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What are Chemotherapeutic agents?
- control microbial growth internally
- can be synthetic or produced by microbes (antibiotics)
What is a therapeutic ratio
- highest dose that will control infection and patient can tolerate without toxic effects
- ideal antibiotic has high therapeutic ratio
How do antibiotics work?
- exploit differences between prokaryotic/eukaryotic microbes and mammalian cells:
- bacteria
- fungal cell walls
- Prokaryotic ribosomes
- RNA polymerases
Chemotherapeutic Agents - Growth Factor Analogs
- 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
Chemotherapeutic Agents - Base Analogs
- Substituted base analogs are effective anti-virals and anti-fungals
- Inhibit DNA replication and RNA transcription
What effect do common Chemotherapeutic agents have on cells?
- Inhibit baterial cell wall synthesis
- Prevent cross-linkage of NAM subunits
- results in weakened cell walls and eventually lysis
Penicillin and derivitives make up what portion of all antibiotics?
- over half!
- All contain the B-lactam ring
- bacterial B-lactamases target this ring to inactivate the antibiotic
Types of Penicillin derivatives?
- 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
What are some other cell wall-disrupting antibiotics?
- Vancomycin

- Bacitracin

- Isoniazid and ethambutol
How do inhibitors of protein synthesis work?
- 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
What are Aminoglycosides?
- 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
What are Macrolides?
- 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
What are tetracyclines?
- Bacteria-produced broad-spectrum antibiotics
- naphthacene ring system
- can substitute at several positions to form new antibiotics
- inhibits translation elongation at 30S subunit
What are polyenes?
- 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
What are Azoles?
- Anti-fungal drugs
- effects membrane by inhibiting ergosterol synthesis
- fluconazole (Diflucan)
- intraconazole
What are Allyamines?
- Anti-fungal drugs
- effects membranes
- terbinafine (Lamisil)
What are Echinocandins?
- Anti-fungal drugs
- effects cell wall
- caspofungin (Cancidas)
What are the types of Anti-Fungal Drugs?
- Polyenes
- Azoles
- Allyamines
- Echinocandins
Why do anti-viral drugs also affect host cells?
- Viruses use host cell machinery to grow and reproduce within host cells
- anti-viral drugs also effect host cells producing serious side-effects
What causes antibiotic resistance?
- resistance is correlated with inappropriate, extensive use of antibiotics and inadequate dosage or time of administration
What are some mechanisms of Antibiotic Resistance?
- Reduced permeability
- Inactivation of the antibiotic
- Alteration of the target
- Development of resistant pathway
- Efflux (pumping out of cell)
How are new anti-microbial drugs developed?
- Analogs of existing drugs
- modify structures to improve potency, solubility, etc
- Computer-based design creates and tests new molecules