Multiple Choice Questions

The following molecules are involved in the biosynthetic pathway that leads to the formation of DNA and RNA; what is their correct sequence in this pathway? a. PABA b. tetrahydrofolic acid c. purine and pyrimidine nucleotides d. dihydrofolic acid
  • 8 μg/ml. If 16 μg/ml is a bactericidal concentration of the drug, then a bacteriostatic concentration (reflected by the MIC value) would be expected to be lower. Typically, it would be the next lowest concentration of the drug in the serial dilutions being tested.
  • intravenous- intramuscular- oral- topical
  • PABA- dihydrofolic acid- tetrahydrofolic acid- purine and pyrimidine nucleotides.In this biosynthetic pathway, dihydrofolic acid is enzymatically produced from PABA. Dihydrofolic acid is then converted into tetrahydrofolic acid, which is subsequently converted into purine and pyrimidine nucleotides. These become the building blocks of DNA and RNA.
  • Oral - stays flat most of the time, raises slightly in the middle of the curveIntramuscular - raises to mid range in the beginning then drops as the curve continuesContinuous- raises to the top in the very beginning and remains high the entire curve, never drops
Why would beta-lactam drugs typically be considered more active against Gram-positive bacteria and less so against Gram-negative bacteria?
  • 8 μg/ml. If 16 μg/ml is a bactericidal concentration of the drug, then a bacteriostatic concentration (reflected by the MIC value) would be expected to be lower. Typically, it would be the next lowest concentration of the drug in the serial dilutions being tested.
  • The cell walls of Gram-positive bacteria have a thick peptidoglycan component.The damage from beta-lactam action affects a greater proportion of the Gram-positive cell walls than Gram-negative cell walls.
  • Penicillin disrupts the cell wall, which is located outside of the cell membrane.
  • Oral - stays flat most of the time, raises slightly in the middle of the curveIntramuscular - raises to mid range in the beginning then drops as the curve continuesContinuous- raises to the top in the very beginning and remains high the entire curve, never drops
Why do the beta-lactam drugs affect bacteria but NOT human cells?
  • Chemotherapeutic agents should act against the pathogen and not the host.
  • the drug will kill or inhibit the growth of all of the sensitive bacterial cells
  • The beta-lactam antibiotics act on bacterial cell walls; human cells do not have cell walls.Beta-lactams prevent NAM subunit cross-linkages affecting the peptidoglycan layer of the Gram-positive cell wall. Human cells do not have cell walls; therefore, beta-lactam drugs do not affect them.
  • Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.
If the MBC for a particular drug is 16 μg/ml, which of the following serial dilutions of the drug is likely to be the MIC? 1.6 μg/ml 8 μg/ml 24 μg/ml 32 μg/ml
  • PABA- dihydrofolic acid- tetrahydrofolic acid- purine and pyrimidine nucleotides.In this biosynthetic pathway, dihydrofolic acid is enzymatically produced from PABA. Dihydrofolic acid is then converted into tetrahydrofolic acid, which is subsequently converted into purine and pyrimidine nucleotides. These become the building blocks of DNA and RNA.
  • The cell walls of Gram-positive bacteria have a thick peptidoglycan component.The damage from beta-lactam action affects a greater proportion of the Gram-positive cell walls than Gram-negative cell walls.
  • 8 μg/ml. If 16 μg/ml is a bactericidal concentration of the drug, then a bacteriostatic concentration (reflected by the MIC value) would be expected to be lower. Typically, it would be the next lowest concentration of the drug in the serial dilutions being tested.
  • Oral - stays flat most of the time, raises slightly in the middle of the curveIntramuscular - raises to mid range in the beginning then drops as the curve continuesContinuous- raises to the top in the very beginning and remains high the entire curve, never drops
Put the following routes of administration in order, from the route that results in the highest concentration of drug in the bloodstream to the route that results in the lowest concentration: a. topical b. intravenous c. oral d. intramuscular
  • inhibition of host cellular enzymes
  • intravenous- intramuscular- oral- topical
  • prevents the formation of peptide bonds
  • Mycobacteria reproduce very slowly.
Describe the administration route of the chemotherapeutic agent on the curve.OralIntramuscularContinuous
  • erythromycin
  • The cell walls of Gram-positive bacteria have a thick peptidoglycan component.The damage from beta-lactam action affects a greater proportion of the Gram-positive cell walls than Gram-negative cell walls.
  • 8 μg/ml. If 16 μg/ml is a bactericidal concentration of the drug, then a bacteriostatic concentration (reflected by the MIC value) would be expected to be lower. Typically, it would be the next lowest concentration of the drug in the serial dilutions being tested.
  • Oral - stays flat most of the time, raises slightly in the middle of the curveIntramuscular - raises to mid range in the beginning then drops as the curve continuesContinuous- raises to the top in the very beginning and remains high the entire curve, never drops
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Multiple Choice Questions
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