Deck 12: Antimicrobial Agent Mechanisms of Action and Resistance Mechanisms

Question 1

This antibiotic affects the DNA replication by targeting topoisomerases II and IV, enzymes considered important in controlling DNA replication.

A) Glycopeptide
B) Sulfamethoxazole
C) Trimethoprim
D) Quinolone

Answer 1

D

Question 2

These antibiotics are cationic carbohydrate-containing molecules, and their positive charge provides the basis for their interaction with the 30S ribosomal subunit. What class of antibiotic are these?

A) Sulfamethoxazole
B) Trimethoprim
C) Aminoglycosides
D) Peptidoglycans

Answer 2

C

Question 3

This antibiotic interferes with DNA transcription by blocking of RNA chain elongation.

A) Rifampin
B) Quinolone
C) Trimethoprim
D) Glycopeptide

Answer 3

A

Question 4

All of the following are $\beta$ -lactam antibiotics, except

A) penems.
B) monobactams.
C) carbapenems.
D) monoterpenes.

Question 5

Mechanisms that mediate intrinsic antibiotic resistance include all the following, except

A) cell wall impermeability.
B) biofilm formation.
C) expression of genes mediating inactivating enzymes.
D) alternate biosynthetic pathways.

Question 6

The outer membrane of gram-negative bacteria is composed of

A) lipopolysaccharides, phospholipids, and porin proteins.
B) peptidoglycan, phospholipids, and proteins.
C) enzymes, cholesterol, and carbohydrates.
D) carbohydrates, peptidoglycan, and proteins.

Question 7

The members of the polyketide class of antibiotics include all the following, except

A) tetracycline.
B) doxycycline.
C) minocycline.
D) oxycycline.

Question 8

In gram-positive bacteria, this is substantially thicker and more multilayered than in gram-negative bacteria.

A) Lipopolysaccharide
B) Phospholipid
C) Peptidoglycan
D) Cholesterol

Question 9

Antibiotics work by targeting all of the following, except

A) DNA replication.
B) bacterial plasmid DNA.
C) bacterial cell wall.
D) RNA transcription.

Question 10

Antibiotic mechanisms of action target all the following, except

A) blocking the Embden-Meyerhof pathway.
B) bacterial cell wall synthesis.
C) DNA replication.
D) RNA transcription.

Question 11

Penicillins, cephalosporins, monobactams, and carbapenems all have this ring in their structure that is responsible for inhibiting the transpeptidation reaction, resulting in bacterial lysis and cell death.

A) Benzene
B) $\beta$ -Lactam
C) $\alpha$ -Lactam
D) Cephems

Question 12

Which antibiotic inhibits folate synthesis, providing the essential precursor molecule, pyridine thymidylate, needed in DNA synthesis?

A) Vancomycin
B) Quinolones
C) Aminoglycosides
D) Sulfamethoxazole

Question 13

The members of the macrolide class of antibiotics include all the following, except

A) rifamycin.
B) erythromycin.
C) clarithromycin.
D) azithromycin.

Question 14

What is the mechanism of action of the glycopeptides (vancomycin and teicoplanin)?

A) The glycopeptides inhibit folate synthesis and prevent the bacteria from using this as an energy source.
B) The glycopeptides interfere with DNA replication and disrupt the protein synthesis operation.
C) The glycopeptides bind to the substrate of the transpeptidation enzyme and disrupt the cell membrane construction.
D) The glycopeptides interfere with transfer RNA production and disrupt the protein synthesis operation.

Question 15

These two classes of antibiotics allow initiation and mRNA translation to begin, but they act by inhibiting peptide elongation.

A) Aminoglycosides and glycopeptidians
B) Aminoglycosides and quinolones
C) Macrolides and tetracyclines
D) Macrolides and quinolones

Question 16

Both gram-positive and gram-negative bacteria have an inner cytoplasmic membrane that is composed of

A) nucleotides.
B) phospholipids and proteins.
C) cholesterol and carbohydrates.
D) lipopolysaccharides.

Question 17

All of the following antibiotics target the 50S ribosomal subunit to prevent mRNA translation in the bacteria, except

A) macrolides.
B) quinolones.
C) oxazolidinones.
D) streptogramins.

Question 18

All of the following are recently approved classes of antibiotics that target protein synthesis, except

A) sixth generation cephalosporins.
B) oxazolidinones.
C) streptogramin.
D) glycylcycline.

Question 19

Which of the following public health issues is uniting scientists from across the world to develop strategies to address it?

A) Reclassifying bacteria according to their genomes
B) The shortage of low toxicity antifungal drugs
C) Antibiotic resistance
D) Emerging pathogens

Question 20

Relatively nontoxic antimicrobial therapeutic agents include all of the following, except

A) heavy metals.
B) antibiotics.
C) preservatives.
D) antiseptics.

Question 21

$\beta$ -Lactamases hydrolyze $\beta$ -lactam antibiotics using two distinct mechanisms: those having a metallo-based mechanism of action and those with

A) ring-specific enzymes.
B) a serine-based mechanism of action.
C) a chromosomal mechanism of action.
D) a transporter mechanism of action.

Question 22

Intrinsic mechanisms of resistance are

A) those that inhibit protein synthesis and RNA transcription.
B) those that a bacterium acquires through plasmids.
C) also called inducible enzymes.
D) innate characteristics of the bacterium and transmitted to progeny.

Question 23

Extended $\beta$ -lactamases target all the following antibiotics, except

A) penicillins.
B) cephalosporins.
C) monobactams.
D) macrolides.

Question 24

The $\beta$ -lactam agents consist of all the following antibiotics, except

A) vancomycin.
B) penicillins.
C) cephalosporins.
D) carbapenems.

Question 25

A young, healthy patient goes into the hospital for reconstructive knee surgery and spikes a fever the day after surgery. The doctor finds the patient has a nosocomial infection with methicillin-resistant Staphylococcus aureus (MRSA). What antibiotic should the doctor use to treat this patient?

A) Penicillin
B) Aminoglycosides
C) Macrolides
D) Vancomycin

Question 26

Efflux pumps

A) allow nutrients into the cells through specialized channels in the bacteria's outer membrane.
B) allow electrolytes into the cells through specialized channels in the bacteria's outer membrane.
C) act as a semi-permeable membrane and maintain the cell's osmotic pressure.
D) function as transporter proteins involved in the removal of toxic substances from the interior of the cell to the external environment.

Question 27

The primary mechanism of resistance to this antimicrobial class is modification by mutations encoding single amino acid changes in these targets. What antibiotic class is this?

A) Macrolides
B) Quinolones
C) Peptidoglycans
D) Aminoglycosides

Question 28

Plasmids are

A) circular structures present in bacteria that contain genes encoding proteins and DNA and have the capacity to self-replicate and portion into daughter cells during cellular division.
B) DNA elements that encode transposition and excision function and can transpose from one place on the chromosome to another.
C) genetic elements capable of integrating resistance genes (cassettes) by an integron-encoded, site-specific recombinase.
D) DNA elements found in bacteria that carry genes only for the enzymes needed to promote their own transposition.

Question 29

Acquired antibiotic resistance mechanisms include

A) efflux mechanisms.
B) acquisition of new targets.
C) modification of existing antibiotic targets.
D) All of the above

Question 30

How does Staphylococcus aureus acquire resistance to methicillin?

A) An enzyme alteration
B) Mobile DNA element
C) Frameshift mutation
D) RNA porin

Question 31

Streptococcus pneumoniae and Streptococcus pyogenes use efflux as an effective mechanism for acquired resistance to

A) macrolides.
B) peptidoglycans.
C) aminoglycosides.
D) quinolones.

Question 32

This type of resistance mechanism modifies the antibiotic targets and results in reduced affinity of antibiotics for their microbial targets.

A) Cell wall inhibition
B) Protein synthesis modification
C) Enzyme alteration
D) Frameshift mutation

Question 33

This is one of the first resistance mechanisms identified and is a strategy that bacteria use successfully to survive the action of many classes of antibiotics.

A) Frameshift mutation
B) Plasmid DNA acquisition
C) Acquisition of inactivating enzymes
D) Impermeability to the cell wall

Question 34

How do the $\beta$ -lactamase inhibitors work?

A) By structurally rearranging the $\beta$ -lactamase molecule so that it loses specificity for the $\beta$ -lactam antibiotic
B) By competing with the antibiotic for porin sites on the outer membrane
C) By acting as substrates for the $\beta$ -lactamase and reducing their effect on the antibiotic
D) By acting as transport molecules to transport the antibiotic into the bacterial cell

Question 35

A patient undergoes a colon resection. Because of the amount of bacteria present in the colon, the physician put the patient on broad-spectrum antibiotics after surgery. The patient develops a fever 2 days after surgery. He developed an infection with vancomycin-resistant enterococci (VRE). What antibiotics can be used to treat this organism?

A) Synercid
B) Quinolones
C) Aminoglycosides
D) Erythromycin

Question 36

Acquired mechanisms of resistance are those that

A) are passed on from one bacteria to the next using pili.
B) are the result of a frameshift mutation in chromosomal DNA.
C) result from acquisition of DNA by acquisition of extrachromosomal DNA.
D) passed on from generation to generation.

Question 37

Resistance to aminoglycosides is mediated by

A) efflux.
B) changes in the target site.
C) impermeability or by enzymatic modification of amino and hydroxy moieties appended to the cyclitol rings.
D) All of the above

Question 38

Biofilms are groups of bacteria that are irreversibly attached to surfaces and are embedded in a matrix of extracellular polymeric substances. They are most commonly found on

A) native heart valves.
B) dialysis shunts.
C) indwelling medical devices.
D) patient beds.

Question 39

What is a porin?

A) An inner membrane pore that allows proteins out into the cytoplasm
B) Outer membrane pores that allow the membrane to "breathe"
C) Substrates for enzymes that enable protein synthesis
D) Outer membrane channels that permit the inflow of nutrients and the outflow of wastes

Question 40

This type of pathogen may demonstrate decreases or loss of porin synthesis in combination with other resistance mechanisms, resulting in multidrug-resistant pathogens.

A) Nosocomial
B) Community-acquired
C) Emerging
D) Gram-negative

Question 41

Insertion sequences are

A) circular structures present in bacteria that contain genes encoding proteins and RNA, and the capacity to self-replicate and portion into daughter cells during cellular division.
B) DNA elements that encode transposition and excision function, and can transpose from one place on the chromosome to another.
C) genetic elements capable of integrating resistance genes (cassettes) by an integron-encoded, site-specific recombinase.
D) DNA elements found in bacteria that carry genes only for the enzymes needed to promote their own transposition.

Question 42

Integrons are

A) circular structures present in bacteria that contain genes encoding proteins and RNA and have the capacity to self-replicate and portion into daughter cells during cellular division.
B) DNA elements that encode transposition and excision function and can transpose from one place on the chromosome to another.
C) genetic elements capable of integrating resistance genes (cassettes) by an integron-encoded, site-specific recombinase.
D) DNA elements found in bacteria that carry genes only for the enzymes needed to promote their own transposition.

Question 43

Transposons are

A) circular structures present in bacteria that contain genes encoding proteins and RNA, and have the capacity to self-replicate and portion into daughter cells during cellular division.
B) DNA elements that encode transposition and excision function and can transpose from one place on the chromosome to another.
C) genetic elements capable of integrating resistance genes (cassettes) by an integron-encoded, site-specific recombinase.
D) DNA elements found in bacteria that carry genes only for the enzymes needed to promote their own transposition.