Chapter 20:Antimicrobial Drugs

45 terms by JKMoe

Create a new folder

Advertisement Upgrade to remove ads

Penicillin was considered a ʺmiracle drugʺ for all of the following reasons except
A) It was the first antibiotic.
B) It doesnʹt affect eukaryotic cells.
C) It inhibits gram-positive cell wall synthesis.
D) It has selective toxicity.
E) None of the above.

A) It was the first antibiotic.

The first antibiotic discovered was
A) Quinine.
B) Salvarsan.
C) Streptomycin.
D) Sulfa drugs.
E) Penicillin.

E) Penicillin.

Most of the available antimicrobial agents are effective against
A) Viruses.
B) Bacteria.
C) Fungi.
D) Protozoa.
E) All of the above.

B) Bacteria.

Antimicrobial peptides work by
A) Inhibiting protein synthesis.
B) Disrupting the plasma membrane.
C) Complementary base-pairing with DNA.
D) Inhibiting cell-wall synthesis.
E) Hydrolyzing peptidoglycan.

B) Disrupting the plasma membrane.

Semisynthetic penicillins differ from natural penicillins in all of the following respects except that both are
A) Broad spectrum.
B) Resistant to penicillinase.
C) Resistant to stomach acids.
D) Bactericidal.
E) None of the above.

D) Bactericidal.

Which of the following antibiotics is not bactericidal?
A) Aminoglycosides
B) Cephalosporins
C) Polyenes
D) Rifampins
E) Penicillin

C) Polyenes

Which one of the following does not belong with the others?
A) Bacitracin
B) Cephalosporin
C) Monobactam
D) Penicillin
E) Streptomycin

E) Streptomycin

The antibiotic tetracycline binds to the 30S subunit of the ribosome as shown in Figure 20.1. The effect is to
A) Prevent attachment of tRNA.
B) Prevent peptide bond formation.
C) Prevent transcription.
D) Stop the ribosome from moving along the mRNA.
E) Prevent attachment of tRNA and mRNA.

B) Prevent peptide bond formation.

The antibiotic cycloheximide binds to the 60S subunit of the ribosome as shown in Figure 20.2. The effect is to
A) Prevent mRNA-ribosome binding in eukaryotes.
B) Prevent peptide bond formation in prokaryotes.
C) Prevent polypeptide elongation in eukaryotes.
D) Prevent transcription in prokaryotes.
E) None of the above.

C) Prevent polypeptide elongation in eukaryotes.

Which of these antimicrobial agents has the fewest side effects?
A) Streptomycin
B) Tetracycline
C) Penicillin
D) Erythromycin
E) Chloramphenicol

C) Penicillin

All of the following act by competitive inhibition except
A) Ethambutol.
B) Isoniazid.
C) Streptomycin.
D) Sulfonamide.
E) None of the above.

C) Streptomycin.

Which of the following methods of action would be bacteriostatic?
A) Competitive inhibition with folic acid synthesis
B) Inhibition of RNA synthesis
C) Injury to plasma membrane
D) Inhibition of cell wall synthesis
E) None of the above

B) Inhibition of RNA synthesis

Which of the following antibiotics is recommended for use against gram-negative bacteria?
A) Polyenes
B) Bacitracin
C) Cephalosporin
D) Penicillin
E) Polymyxin

E) Polymyxin

Which of the following antimicrobial agents is recommended for use against fungal infections?
A) Amphotericin B
B) Bacitracin
C) Cephalosporin
D) Penicillin
E) Polymyxin

A) Amphotericin B

Table 20.1
The following data were obtained from a broth dilution test.
Concentration of Antibiotic X
2 μg/ml
10 μg/ml
15 μg/ml
25 μg/ml
Growth
+
-
-
-
Growth in
Subculture
+
+
-
-

In Table 20.1, the minimal bactericidal concentration of antibiotic X is
A) 2 μg/ml.
B) 10 μg/ml.
C) 15 μg/ml.
D) 25 μg/ml.
E) Canʹt tell.

C) 15 μg/ml.

In Table 20.1, the minimal inhibitory concentration of antibiotic X is
A) 2 μg/ml.
B) 10 μg/ml.
C) 15 μg/ml.
D) 25 μg/ml.
E) Canʹt tell.

B) 10 μg/ml.

More than half of our antibiotics are
A) Produced by fungi.
B) Produced by bacteria.
C) Synthesized in laboratories.
D) Produced by Fleming.
E) None of the above.

B) Produced by bacteria.

The antibiotic erythromycin binds to the 50S subunit of the ribosome as shown in Figure 20.3. The effect is to
A) Prevent attachment of tRNA.
B) Prevent peptide bond formation.
C) Prevent transcription.
D) Stop the ribosome from moving along the mRNA.
E) None of the above.

D) Stop the ribosome from moving along the mRNA.

The antibiotic streptomycin binds to the 30S subunit of the ribosome as shown in Figure 20.4. The effect is to
A) Cause misreading of mRNA in 70S ribosomes.
B) Prevent binding of tRNA in eukaryotes.
C) Prevent polypeptide elongation in eukaryotes.
D) Prevent peptide bond formation in prokaryotes.
E) None of the above.

A) Cause misreading of mRNA in 70S ribosomes.

Which compound would be the most useful to treat candidiasis?
A) Uracil
B) Thymine
C) Flucytosine
D) Guanine
E) None of the above

C) Flucytosine

Which of the following antibiotics are used to treat fungal infections?
1. Aminoglycosides
2. Cephalosporins
3. Griseofulvin
4. Polyenes
5. Bacitracin

A) 1, 2, and 3
B) 3 and 4
C) 3, 4, and 5
D) 4 and 5
E) All of the antibiotics

B) 3 and 4

All of the following antibiotics interfere with cell wall synthesis except
A) Cephalosporins.
B) Macrolides.
C) Natural penicillins.
D) Semisynthetic penicillins.
E) Vancomycin

B) Macrolides.

The antimicrobial drugs with the broadest spectrum of activity are
A) Aminoglycosides.
B) Chloramphenicol.
C) Lincomycin.
D) Macrolides.
E) Tetracyclines.

E) Tetracyclines.

Which of the following statements is false?
A) Fluoroquinolone inhibits DNA synthesis.
B) Acyclovir inhibits DNA synthesis.
C) Amantadine inhibits release of viral nucleic acid.
D) Interferon inhibits glycolysis.
E) None of the above.

D) Interferon inhibits glycolysis.

Protozoan and helminthic diseases are difficult to treat because
A) Their cells are structurally and functionally similar to human cells.
B) They replicate inside human cells.
C) They donʹt have ribosomes.
D) They donʹt reproduce.
E) None of the above.

A) Their cells are structurally and functionally similar to human cells.

Which of the following organisms would most likely be sensitive to natural penicillin?
A) L forms
B) Streptococcus pyogenes
C) Penicillinase-producing Neisseria gonorrhoeae
D) Penicillium
E) Mycoplasma

B) Streptococcus pyogenes

All of the following statements about drug resistance are true except
A) It may be carried on a plasmid.
B) It may be transferred from one bacterium to another during conjugation.
C) It may be due to enzymes that degrade some antibiotics.
D) It is found only in gram-negative bacteria.
E) It may be due to increased uptake of a drug.

D) It is found only in gram-negative bacteria.

All of the following are advantages of using two antibiotics together except
A) Prevention of drug resistance.
B) Lessening the toxicity of individual drugs.
C) Two are always twice as effective as one.
D) Providing treatment prior to diagnosis.
E) None of the above.

C) Two are always twice as effective as one.

Drug resistance occurs
A) Because bacteria are normal microbiota.
B) When antibiotics are used indiscriminately.
C) Against antibiotics and not against synthetic chemotherapeutic agents.
D) When antibiotics are taken after the symptoms disappear.
E) All of the above.

B) When antibiotics are used indiscriminately.

Table 20.2
The following results were obtained from a disk-diffusion test for microbial
susceptibility to antibiotics. Staphylococcus aureus was the test organism.
Antibiotic Zone of Inhibition
A 3 mm
B 7 mm
C 0 mm
D 10 mm

In Table 20.2, the most effective antibiotic tested was
A) A.
B) B.
C) C.
D) D.
E) Canʹt tell.

D. 10 mm

In Table 20.2, the antibiotic that exhibited bactericidal action was
A) A.
B) B.
C) C.
D) D.
E) Canʹt tell.

E) Canʹt tell.

In Table 20.2, which antibiotic would be most useful for treating a Salmonella infection?
A) A
B) B
C) C
D) D
E) Canʹt tell

E) Canʹt tell

Which of the following would be selective against the tubercle bacillus?
A) Bacitracin  inhibits peptidoglycan synthesis
B) Ethambutol  inhibits mycolic acid synthesis
C) Streptogramin  inhibits protein synthesis
D) Streptomycin  inhibits protein synthesis
E) Vancomycin  inhibits peptidoglycan synthesis

B) Ethambutol  inhibits mycolic acid synthesis

In the presence of penicillin a cell dies because
A) It lacks a cell wall.
B) It plasmolyzes.
C) It undergoes osmotic lysis.
D) It lacks a cell membrane.
E) None of the above.

C) It undergoes osmotic lysis.

Lamisil is an allylamine used to treat dermatomycoses. Lamisilʹs method of action is similar to
A) Polymyxin B.
B) Azole antibiotics.
C) Echinocandins.
D) Griseofulvin.
E) Bacitracin.

B) Azole antibiotics.

Niclosamide prevents ATP generation in mitochondria. You would expect this drug to be effective against
A) Gram-negative bacteria.
B) Gram-positive bacteria.
C) Helminths.
D) Mycobacterium tuberculosis.
E) Viruses.

C) Helminths.

Table 20.3
The following data were obtained from a broth dilution test:
Concentration of Antibiotic X Growth
2.0 μg/ml -
1.0 μg/ml -
0.5 μg/ml -
0.25 μg/ml +
0.125 μg/ml +
0 +

Bacteria from the 0.25 μg/ml tube were transferred to new growth media containing antibiotic X with the following results:
Concentration of Antibiotic X Growth
2.0 μg/ml -
1.0 μg/ml +
0.5 μg/ml +
0.25 μg/ml +

37) The data in Table 20.3 show that these bacteria
A) Can be subcultured.
B) Developed resistance to antibiotics.
C) Were killed by 0.125 μg/ml of antibiotic X.
D) Were killed by 0.5 μg/ml of antibiotic X.
E) Were resistant to 1.0 μg/ml at the start of the experiment.

B) Developed resistance to antibiotics.

Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA polymerase is not true?
A) They cause mutations.
B) They are used against viral infections.
C) They affect host cell DNA.
D) They are too dangerous to be used.
E) None of the above.

D) They are too dangerous to be used.

If the compound shown in Figure 20.5 is the substrate for a particular enzyme, which of the drugs would be the most effective competitive inhibitor?
A) a
B) b
C) c
D) d
E) None of the above.

D) d

O CH3
|| _____ /
|| / \----C---CH3
H3C-----C----O----\_____/ \
CH3

Which of the following is not bactericidal?
A) Tetracycline
B) Natural penicillin
C) Streptomycin
D) Bacitracin
E) Semisynthetic penicillin

A) Tetracycline

Which of the following does not affect eukaryotic cells?
A) Antiprotozoan drugs
B) Antihelminthic drugs
C) Antifungal drugs
D) Nucleotide analogs
E) None of the above

E) None of the above

Mebendazole is used to treat cestode infections. It interferes with microtubule formation;
therefore, it would not affect
A) Bacteria.
B) Fungi.
C) Helminths.
D) Human cells.
E) Protozoa.

A) Bacteria.

Which of the following antibiotics causes misreading of mRNA?
A) Aminoglycoside  changes shape of 30S units
B) Chloramphenicol  inhibits peptide bonds at 50S subunit
C) Oxazolidinone  prevents formation of 70S ribosome
D) Streptogamin  prevents release of peptide from 70S ribosome
E) Tetracyclines  bind with 30S subunit

A) Aminoglycoside  changes shape of 30S units

The antibiotic actinomycin D binds between adjacent G-C pairs, thus interfering with
A) Transcription.
B) Translation.
C) Cellular respiration.
D) Plasma membrane function.
E) Peptide bond formation.

A) Transcription.

Use of antibiotics in animal feed leads to antibiotic-resistant bacteria because
A) Bacteria from other animals replace those killed by the antibiotics.
B) The few surviving bacteria that are affected by the antibiotics develop immunity to the antibiotics, which they pass on to their progeny.
C) The antibiotics cause new mutations to occur in the surviving bacteria, which results in resistance to antibiotics.
D) The antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.
E) The antibiotics persist in soil and water.

D) The antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set