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8 Cards in this Set
- Front
- Back
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1. Be able to describe the mechanism of antibacterial actions of the sulfonamide drugs.
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a. Mechanism of antibacterial action of sulfonamides = They are competitive antagonists of para-aminobenzoic acid (PABA). By antagonizing bacterial PABA, these agents prevent the normal bacterial utilization of PABA thus preventing synthesis of folic acid. Lack of folic acid results in lack of bacterial growth and function.
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2. Name and describe the important sulfonamide drug used in medicine today.
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a. Sulfamethoxazole/trimethoprim (Bactrim)
i. Use – most Gm-positive and Gm-negative bacteria are sensitive to this combination of sulfamethoxazole with trimethoprim. This drug is used to treat urinart tract infections due to E. coli and others. It is taken orally as suspension or tablet. ii. Mechanism of the sulfamethoxazole component = interferes with bacterial folic acid synthesis and growth via inhibition of dihydrofolic acid formation from PABA iii. Mechanism of the trimethoprim component = inhibits dihydrofolate acid reduction to tetrahydrolfolate resulting in sequential inhibition of enzymes of the folic acid pathway |
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3. List four important quinolones used in medicine.
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a. Ciprofloxacin (Cipro)
b. Gatifloxacin (Tequin) c. Gemifloxacin (Factive d. Levofloxacin (Levaquin) |
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4. Describe the antibacterial mechanisms of quinolones.
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a. The quinolones target bacterial DNA gyrase (Gm-negative bacteria) and topoisomerase IV (Gm-positive bacteria).
DNA gyrase allows for efficient separation of the two strands of DNA to permit DNA replication and transcription in bacteria. Inhibition of gyrase by the quinolones blocks the replication process. Eukaryotic cells do not contain DNA gyrase. Topoisomerase IV separates “daughter” DNA molecules that are the product of DNA replication. Inhibition of this enzyme by the quinolones blocks the separation and any further DNA replication. Eukaryotic cells contain topoisomerase IV. Quinolones inhibit the eukaryotic topoisomerase only at much higher concentrations |
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5. Describe the general uses of quinolones.
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a. They are used in the treatment of infections of the lower respiratory tract, skin, bone/joints and urinary tract; especially indicated for pseudomonal infections and those due to multi-resistant gm-negative organisms. They are also used to treat community-acquired pneumonia, acute bacterial sinusitis, and used for prevention of inhalation anthrax (postexposure)
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6. List the aminoglycosides “mycins”
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"STANK G"
a. Streptomycin b. Kanamycin c. Gentamicin d. Netilmicin e. Tobramycin f. Amikacin g. Neomycin |
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7. Describe the antibacterial mechanisms of the aminoglycosides.
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a. The aminoglycosides are effective bactericidals and the higher the concentration the greater rate at which bacteria are killed. The aminoglycosides interfere with bacterial protein synthesis by binding to 30S and 50S ribosomal subunits. This results in the formation of aberrant proteins which may be inserted into the bacterial cell membrane leading to altered cell membrane permeability resulting in efflux of cytoplasmic components
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8. Describe the characteristics of the aminoglycosides.
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a. They are all poorly absorbed from GI tract because they are highy polar. Therefore they have to be given by injection. They are all associated with causing ototoxicity (deafness), nephrotoxicity and neuromuscular blockade.
b. Active against gm negative bacilli including Pseudomonas areuginosa, Enterobacter, Klebsiella, Serratia . Highly toxic so you should try other agents first. Never used in dental office |
