Question 1

Antimicrobial resistance resulting from the normal genetic, structural, or physiologic state of a microorganism is referred to as

Accepted Answer

Intrinsic resistance is considered to be a natural and consistently inherited characteristic that is associated with the vast majority of strains that constitute either a particular bacterial group, genus, or species.

Question 2

The mechanism of acquired, high-level resistance to vancomycin involves

Accepted Answer

The mechanism involves altered cell wall precursors that do not bind vancomycin with sufficient avidity to allow inhibition of peptidoglycan synthesizing enzymes. The altered targets are readily incorporated into the cell wall so that synthesis progresses as usual.

Question 3

Match the antimicrobial agent with its mode of action.
-Vancomycin

Accepted Answer

Vancomycin inhibits cell wall synthesis by binding to the D-alanyl-D-alanine portion of the peptidoglycan precursor molecule and preventing elongation of the peptidoglycan chain.

Question 4

Match the antimicrobial agent with its mode of action.
-Rifampin

Accepted Answer

Rifampin inhibits RNA synthesis by binding to the beta subunit of bacterial RNA polymerase, blocking the initiation of transcription.

Question 5

Match the antimicrobial agent with its mode of action.
-Gentamicin

Accepted Answer

Gentamicin inhibits protein synthesis by binding to the bacterial ribosome and preventing the formation of functional proteins.

Question 6

Match the antimicrobial agent with its mode of action.
-Ciprofloxacin

Accepted Answer

Ciprofloxacin inhibits DNA and RNA synthesis, specifically by targeting DNA gyrase and topoisomerase IV, which are enzymes involved in DNA replication and repair.

Question 7

Bacterial resistance to beta-lactams may be mediated by

Accepted Answer

All three pathways listed play an important role in clinically relevant antibacterial resistance, but bacterial destruction of beta-lactams by producing beta-lactamases is by far the most common method of resistance.

Question 8

Antibiotic resistance that results from altered cellular physiology and structure caused by changes in a microorganism's usual genetic makeup is known as

Accepted Answer

Acquired resistance mechanisms are all genetically encoded; therefore the methods for acquisition are those that allow for gene change or exchange. Resistance may be acquired by genetic mutation, gene transfer mechanisms, or a combination of mutational and gene transfer events.

Question 9

Match the antimicrobial agent with its mode of action.
-Tetracycline

Accepted Answer

Tetracycline inhibits bacterial protein synthesis by binding to the 30S subunit of ribosomes, preventing the attachment of aminoacyl-tRNA molecules to the ribosome and thus blocking the elongation of the polypeptide chain.

Question 10

Match the antimicrobial agent with its mode of action.
-Penicillin

Accepted Answer

Penicillin inhibits cell wall synthesis by binding to and disrupting the enzymes responsible for cross-linking the peptidoglycan layers in bacterial cell walls. This leads to weakened cell walls and eventual lysis of the bacteria.

Question 11

Antimicrobial agents that inhibit bacterial growth but generally do not kill the organism are known as

Accepted Answer

Bacteriostatic means inhibition of bacterial growth, whereas bactericidal means killing of bacterial growth.

Question 12

Antimicrobial agents that usually kill target organisms are said to be

Accepted Answer

Bacteriostatic means inhibition of bacterial growth, whereas bactericidal means killing of bacterial growth.

Question 13

Mycoplasmas are organisms without cell walls.Which antimicrobials would be ineffective in treating infections involving this bacterium?

Accepted Answer

Penicillin, among others, is an antibiotic that acts by binding the enzymes that are involved in cell wall synthesis. Because mycoplasmas do not have cells walls, these types of antibiotics would not be effective.

Question 14

Match the antimicrobial agent with its mode of action.
-Polymyxin B

Accepted Answer

Polymyxin B acts by binding to and disrupting the cell membrane of bacteria, causing leakage of cellular contents and ultimately cell death. It does not affect cell wall or protein and nucleic acid synthesis, ruling out options A, C, and D.

Quiz 11: Principles of Antimicrobial Action Resistance

Antimicrobial resistance resulting from the normal genetic, structural, or physiologic state of a microorganism is referred to as

The mechanism of acquired, high-level resistance to vancomycin involves

Match the antimicrobial agent with its mode of action. -Vancomycin

Match the antimicrobial agent with its mode of action. -Rifampin

Match the antimicrobial agent with its mode of action. -Gentamicin

Match the antimicrobial agent with its mode of action. -Ciprofloxacin

Bacterial resistance to beta-lactams may be mediated by

Antibiotic resistance that results from altered cellular physiology and structure caused by changes in a microorganism's usual genetic makeup is known as

Match the antimicrobial agent with its mode of action. -Tetracycline

Match the antimicrobial agent with its mode of action. -Penicillin

Antimicrobial agents that inhibit bacterial growth but generally do not kill the organism are known as

Antimicrobial agents that usually kill target organisms are said to be

Mycoplasmas are organisms without cell walls.Which antimicrobials would be ineffective in treating infections involving this bacterium?

Match the antimicrobial agent with its mode of action. -Polymyxin B