Deck 12: Antibiotic Mechanisms of Action and Resistance

Question 1

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

Answer 1

C
Antibiotic resistance emerged soon after the discovery of antibiotics and is associated with the overuse of antimicrobial agents.Although antibiotics allow the medical community to make great strides in human health and welfare,their use also causes selective pressure,allowing only the fittest and less susceptible bacterial populations to thrive.Antibiotic resistance and its associated clinical failure is an issue of public health concern that is uniting scientists from across the world to develop strategies to address it.

Question 2

Antibiotics work by targeting all of the following EXCEPT:

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

Answer 2

B
Antibiotics target the bacterial cell wall and the cellular machinery responsible for the synthesis of precursor molecules; cellular targets include DNA replication,RNA transcription,and mRNA translation.Although numerous antibiotic classes exist with different modes of action,bacteria evolved and adopted numerous strategies to counteract the action of antibiotics.

Question 3

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

Answer 3

D
Antibiotic resistance may be characterized as intrinsic and is an inherent genotypic characteristic of the microorganism disseminated horizontally to progeny.Mechanisms that mediate intrinsic resistance to antibiotics include cell-wall impermeability,efflux,biofilm formation,and the expression of genes producing inactivating enzymes.

Question 4

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 5

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 6

The members of the polypeptide class of antibiotics include all the following EXCEPT:

A) Tetracycline
B) Doxycycline
C) Minocycline
D) Oxycycline

Question 7

This antibiotic inhibits folate synthesis,which provides the essential precursor molecule,pyridine thymidylate,needed in DNA synthesis.

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

Question 8

The members of the macrolide class of antibiotics include all the following EXCEPT:

A) Rifamycin
B) Erythromycin
C) Clarithromycin
D) Azithromycin

Question 9

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) b-Lactam
C) a-Lactam
D) D-cephems

Question 10

All of the following are b-lactam antibiotics EXCEPT:

A) Penems
B) Monobactams
C) Carbapenems
D) Monoterpenes

Question 11

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 12

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 13

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 14

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

Question 15

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

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

Question 16

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 17

The mechanisms of action of antibiotics include all the following EXCEPT:

A) Blocking the Embden-Meyerhof pathway
B) Bacterial cell wall synthesis
C) DNA replication
D) RNA transcription

Question 18

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 19

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

Question 20

Antimicrobial agents include all of the following EXCEPT:

A) Plant extracts
B) Antibiotics
C) Preservatives
D) Antiseptics

Question 21

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 22

How do the b-lactamase inhibitors work?

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

Question 23

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 semipermeable 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 24

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 25

Antibiotics that demonstrate a narrow spectrum of activity:

A) Kill a wide variety of bacteria.
B) Kill only a few specific types of bacteria.
C) Kill bacteria by using only one specific mechanism.
D) Kill bacteria by using a narrow spectrum of mechanisms.

Question 26

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

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

Question 27

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 28

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 29

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 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

b-Lactamases hydrolyze b-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 32

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 33

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 vertically

Question 34

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

A) Organic heart valves
B) Dialysis shunts
C) Indwelling medical devices
D) Patient beds

Question 35

Extended b-lactamases target all the following antibiotics EXCEPT:

A) Penicillins
B) Cephalosporins
C) Monobactams
D) Macrolides

Question 36

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

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

Question 37

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 38

The b-lactams consist of all the following antibiotics EXCEPT:

A) Vancomycin
B) Penicillins
C) Cephalosporins
D) Carbapenems

Question 39

Acquired antibiotic resistance mechanisms include:

A) Efflux
B) Acquisition of new targets
C) Modification of existing antibiotic targets
D) All of the above

Question 40

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 41

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 42

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

Question 43

Plasmids 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 44

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