MIC 541-Exam 4- Antimicrobials III-3

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MIC 541-Exam 4- Antimicrobials III-3
2013-04-14 12:11:20
MIC 541 Exam Antimicrobials III

MIC 541-Exam 4- Antimicrobials III-3
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  1. What is the synergistic effect of Penicillin with Aminoglycoside enterococci?
    • On their own = Bacteriostatic
    • Combination = Bacteriocidal
  2. What is the synergistic effect of Trimethoprim and Sulfamthoxazole?
    • Each alone = antimetabolite, inhibit sequential folic acid synthesis steps
    • Together = shuts off pathway and kills cells
  3. What are the two antibiotics found in Synercid?
    Sterptogramin A and Streptogramin B
  4. Streptogramin A and Streptogramin B together make up what antibiotic?
  5. What is the synergistic effect of Streptogramin A and B (in Synercid)?
    • On their own = bacteriostatic
    • Together = Bacteriocidal
  6. What combination of Drugs discussed in class are Folic acid antimetabolites that inhibit sequential steps and when combined shut off folic acid synthesis and kill the cell
    Trimethoprim and Sulfamethoxazole
  7. What classification of antibiotic is Synercid?
    protein synthesis inhibitor
  8. Describe the antimetabolic action of Sulfonamide?
    Competitive inhibitor for the Active site on the enzyme that binds PABA
  9. (T/F) No tetrahydrofolic acid is produced from PABA after treatment with sulfonamide?
    False, some is still produced
  10. What example was given in class for drug antagonism?
    B-lactam and Bacteriostatic drugs
  11. Why can B -lactams not be administered with Bacteriostatic drugs?
    B-lactams are growth dependant. Bacteriostatic inhibit growth.
  12. What antibiotic discussed in class cannot be administered with bacteriostatics because it is growth dependant?
  13. How often do mutant cells arise?
    1:10^5 to 1:10^9
  14. On average how long does it take for 10^9 cells to grow from 1 cell?
  15. Can combination therapy prevent resistance?
    Only if one of the drugs is able to kill the emergent mutant
  16. Does Ticarcillin or Ceftazidime mutate mre frequently?
    • Ceftazidime mutates 10 times for frequently (10^6 vs. 10^7)
    • In the Ticarcillin/Ceftazidime study presented in class what was the most important factor contributing to successful inhibition of bacterial growth?
    • MIC of the mutant
    • Peak:MIC of the mutant
  17. Mutation frequency alone is the most important factor for determining resistance (T/F)?
    False, Mutation frequency alone is meaningless
  18. What is the most important factor when assessing the development of resistance?
    Drug MIC for mutants vs the kinetics of the drug