Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Table 20.1
The following data were obtained from a broth dilution test.
Concentration of Antibiotic X Growth Growth in
Subculture
2 µg/ml + +
10 µg/ml – +
15 µg/ml – –
25 µg/ml – –
1)
In Table 20.1, the minimal bactericidal concentration of antibiotic X is
1)
A)
2 µg/ml.
B)
25 µg/ml.
C)
15 µg/ml.
D)
10 µg/ml.
E)
The answer cannot be determined based on the information provided.
2)
Which of the following antibiotics is NOT bactericidal?
2)
A)
rifampins
B)
aminoglycosides
C)
cephalosporins
D)
penicillin
E)
polyenes
E
C
3)
To date, most of our natural antibiotics have been found to be produced by members of what
genus?
3)
A)
Streptomyces
B)
Cephalosporium
C)
Penicillium
D)
Paenibacillus
E)
Bacillus
4)
The substrate for transpeptidase used to synthesize peptidoglycan is shown in Figure 20.3. Which
of the drugs shown would inhibit peptidoglycan synthesis?
4)
A)
a
B)
b
C)
c
D)
d
E)
e
5)
In the presence of penicillin, a cell dies because
5)
A)
it undergoes lysis.
B)
its contents leak out.
C)
it plasmolyzes.
D)
it lacks a cell membrane.
E)
it lacks a cell wall.
6)
Lamisil is an allylamine used to treat dermatomycoses. Lamisil’s method of action is similar to that
of
6)
A)
griseofulvin.
B)
bacitracin.
C)
polymyxin B.
D)
echinocandins.
E)
azole antibiotics.
7)
In what way are semisynthetic penicillins and natural penicillins alike?
7)
A)
Both are resistant to penicillinase.
B)
Both are resistant to stomach acids.
C)
Both are bactericidal.
D)
Both are based on –lactam.
E)
Both are broad spectrum.
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
A3 mm
B7 mm
C 0 mm
D10 mm
8)
In Table 20.2, the most effective antibiotic tested was
8)
A)
A.
B)
B.
C)
C.
D)
D.
E)
The answer cannot be determined based on the information provided.
9)
In Table 20.2, the antibiotic that exhibited bactericidal action was
9)
A)
A.
B)
B.
C)
C.
D)
D.
E)
The answer cannot be determined based on the information provided.
E
10)
Which of the following would be selective against the tubercle bacillus?
10)
A)
ethambutol inhibits mycolic acid synthesis
B)
streptomycin inhibits protein synthesis
C)
bacitracin inhibits peptidoglycan synthesis
D)
vancomycin inhibits peptidoglycan synthesis
E)
streptogramin inhibits protein synthesis
A
D
11)
Which of the following does NOT constitute an advantage of using two antibiotics together?
11)
A)
It lessens the toxicity of individual drugs.
B)
Two are always twice as effective as one.
C)
It can prevent drug resistance.
D)
It allows treatment to be provided prior to diagnosis.
E)
All of these are advantages of using two antibiotics together.
12)
Which of the following methods of action would be bacteriostatic?
12)
A)
competitive inhibition with folic acid synthesis
B)
competitive inhibition with DNA gyrase
C)
inhibition of protein synthesis
D)
injury to plasma membrane
E)
inhibition of cell wall synthesis
13)
Penicillin was considered a “miracle drug” for all of the following reasons EXCEPT
13)
A)
it was the first antibiotic.
B)
it inhibits gram–positive cell wall synthesis.
C)
it does not affect eukaryotic cells.
D)
it kills bacteria.
E)
it has selective toxicity.
14)
Mebendazole is used to treat cestode infections. It interferes with microtubule formation; therefore,
it would NOT affect
14)
A)
human cells.
B)
fungi.
C)
protozoa.
D)
helminths.
E)
bacteria.
15)
Which of the following antibiotics are used to treat fungal infections?
1. aminoglycosides
2. cephalosporins
3. griseofulvin
4. polyenes
5. bacitracin
15)
A)
1, 2, and 3
B)
3 and 4
C)
3, 4, and 5
D)
4 and 5
E)
All of these antibiotics are used to treat fungal infections.
16)
Which of the following antibiotics causes misreading of mRNA?
16)
A)
chloramphenicol inhibits peptide bonds at 50S subunit
B)
oxazolidinone prevents formation of 70S ribosome
C)
aminoglycoside changes shape of 30S units
D)
streptogamin prevents release of peptide from 70S ribosome
E)
tetracyclines bind with 30S subunit
17)
More than half of our antibiotics are
17)
A)
produced by Fleming.
B)
produced by fungi.
C)
produced by eukaryotic organisms.
D)
produced by bacteria.
E)
synthesized in laboratories.
18)
Which of the following drugs does NOT act by competitive inhibition?
18)
A)
isoniazid
B)
streptomycin
C)
trimethoprim
D)
ethambutol
E)
sulfonamide
19)
The antibiotic tetracycline binds to the 30S subunit of the ribosome, as shown in Figure 20.1. The
effect is to
19)
A)
prevent attachment of DNA.
B)
prevent transcription.
C)
stop the ribosome from moving along the mRNA.
D)
prevent peptide bond formation.
E)
interfere with the attachment of the tRNA to mRNA–ribosome complex.
Figure 20.4
20)
The structures of the influenza drug Tamiflu and sialic acid, the substrate for influenza virus’s
neuramidase, are shown in Figure 20.4. What is the method of action of Tamiflu?
20)
A)
prevents synthesis of virus spikes
B)
inhibits cell wall synthesis
C)
competitive inhibition
D)
inhibits plasma membrane synthesis
E)
inhibits synthesis of neuramidase
21)
The antimicrobial drugs with the broadest spectrum of activity are
21)
A)
chloramphenicol.
B)
aminoglycosides.
C)
penicillin G.
D)
tetracyclines.
E)
macrolides.
22)
Which of the following statements about drug resistance is FALSE?
22)
A)
It may be due to enzymes that degrade some antibiotics.
B)
It may be carried on a plasmid.
C)
It is found only in gram–negative bacteria.
D)
It may be due to increased uptake of a drug.
E)
It may be transferred from one bacterium to another during conjugation.
Figure 20.2
23)
The antibiotic cycloheximide binds to the 60S subunit of the ribosome, as shown in Figure 20.2. The
effect is to
23)
A)
prevent peptide bond formation in prokaryotes.
B)
prevent mRNAribosome binding in eukaryotes.
C)
prevent ribosome formation in bacteria.
D)
prevent transcription in prokaryotes.
E)
prevent polypeptide elongation in eukaryotes.
24)
Which of the following antimicrobial agents has the fewest side effects?
24)
A)
penicillin
B)
streptomycin
C)
chloramphenicol
D)
erythromycin
E)
tetracycline
25)
The antibiotic actinomycin D binds between adjacent G–C pairs, thus interfering with
25)
A)
peptide bond formation.
B)
transcription.
C)
plasma membrane function.
D)
cellular respiration.
E)
translation.
26)
Most of the available antimicrobial agents are effective against
26)
A)
fungi.
B)
viruses.
C)
bacteria.
D)
protozoa.
E)
All of the answers are correct.
27)
A drug that inhibits mitosis, such as griseofulvin, would be more effective against
27)
A)
fungi.
B)
mycobacteria.
C)
gram–positive bacteria.
D)
wall–less bacteria.
E)
gram–negative bacteria.
A
28)
Which of the following does NOT affect eukaryotic cells?
28)
A)
antihelminthic drugs
B)
semisynthetic penicillins
C)
antiprotozoan drugs
D)
antifungal drugs
E)
nucleotide analogs
B
29)
Which of the following antibiotics is recommended for use against gram–negative bacteria?
29)
A)
polymyxin
B)
cephalosporin
C)
bacitracin
D)
polyenes
E)
penicillin
A
C
30)
Which of the following antimicrobial agents is recommended for use against fungal infections?
30)
A)
polymyxin
B)
amphotericin B
C)
cephalosporin
D)
penicillin
E)
bacitracin
31)
Protozoan and helminthic diseases are difficult to treat because
31)
A)
their cells are structurally and functionally similar to human cells.
B)
they replicate inside human cells.
C)
they have more genes than bacteria.
D)
they do not reproduce.
E)
they do not have ribosomes.
A
Explanation:
32)
Which of the following organisms would MOST likely be sensitive to natural penicillin?
32)
A)
Penicillium
B)
penicillinase–producing Neisseria gonorrhoeae
C)
Streptococcus pyogenes
D)
helminths
E)
Mycoplasma
C
Explanation:
33)
Which compound would be the most useful to treat candidiasis?
33)
A)
penicillin
B)
guanine
C)
uracil
D)
thymine
E)
flucytosine
E
Explanation:
B
Explanation:
34)
Antimicrobial peptides work by
34)
A)
disrupting the plasma membrane.
B)
complementary base pairing with DNA.
C)
hydrolyzing peptidoglycan.
D)
inhibiting cell–wall synthesis.
E)
inhibiting protein synthesis.
35)
Which one of the following does NOT belong with the others?
35)
A)
monobactam
B)
cephalosporin
C)
streptomycin
D)
bacitracin
E)
penicillin
C
36)
Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA
polymerase is FALSE?
36)
A)
They cause cellular plasmolysis.
B)
They are used against viral infections.
C)
They interfere with protein synthesis.
D)
They cause mutations.
E)
They can affect host cell DNA.
A
37)
Which of the following is mismatched?
37)
A)
Florey and Chain – identification of Penicillium as the producer of penicillin
B)
Fleming – identification of penicillin
C)
Ehrlich – “magic bullet” theory
D)
Kirby and Bauer – disc–diffusion method
E)
None of these is mismatched.
A
A
38)
Use of antibiotics in animal feed leads to antibiotic–resistant bacteria because
38)
A)
bacteria from other animals replace those killed by the antibiotics.
B)
the antibiotics persist in soil and water.
C)
the few surviving bacteria that are affected by the antibiotics develop immunity to the
antibiotics, which they pass on to their progeny.
D)
the antibiotics cause new mutations to occur in the surviving bacteria, which results in
resistance to antibiotics.
E)
the antibiotics kill susceptible bacteria, but the few that are naturally resistant live and
reproduce, and their progeny repopulate the host animal.
39)
Which of the following antibiotics does NOT interfere with cell wall synthesis?
39)
A)
cephalosporins
B)
vancomycin
C)
macrolides
D)
natural penicillins
E)
semisynthetic penicillins
40)
Niclosamide prevents ATP generation in mitochondria. You would expect this drug to be effective
against
40)
A)
Mycobacterium tuberculosis.
B)
gram–negative bacteria.
C)
gram–positive bacteria.
D)
viruses.
E)
helminths.
41)
Drug resistance occurs
41)
A)
when antibiotics are used indiscriminately.
B)
against antibiotics and not against synthetic chemotherapeutic agents.
C)
when antibiotics are taken after the symptoms disappear.
D)
because bacteria are normal microbiota.
E)
All of the answers are correct.
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 +
0.25µg/ml +
42)
The data in Table 20.3 show that these bacteria
42)
A)
developed resistance to antibiotics.
B)
are pathogenic.
C)
were killed by 0.5 µg/ml of antibiotic X.
D)
were killed by 0.125 µg/ml of antibiotic X.
E)
were resistant to 1.0 µg/ml at the start of the experiment.
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
A3 mm
B7 mm
C 0 mm
D10 mm
43)
In Table 20.2, which antibiotic would be most useful for treating a Salmonella infection?
43)
A)
A
B)
B
C)
C
D)
D
E)
The answer cannot be determined based on the information provided.
Table 20.1
The following data were obtained from a broth dilution test.
Concentration of Antibiotic X Growth Growth in
Subculture
2 µg/ml + +
10 µg/ml – +
15 µg/ml – –
25 µg/ml – –
44)
In Table 20.1, the minimal inhibitory concentration of antibiotic X is
44)
A)
10 µg/ml.
B)
15 µg/ml.
C)
25 µg/ml.
D)
2 µg/ml.
E)
The answer cannot be determined based on the information provided.
A
E
45)
Which of the following statements is FALSE?
45)
A)
Acyclovir inhibits DNA synthesis.
B)
Interferon inhibits glycolysis.
C)
Amantadine inhibits the release of viral nucleic acid.
D)
Azoles inhibit plasma membrane synthesis.
E)
Fluoroquinolone inhibits DNA synthesis.
TRUE/FALSE. Write ‘T’ if the statement is true and ‘F’ if the statement is false.
46)
Penicillin and streptomycin are commonly used in syngerism because they display the same mode
of action.
46)
47)
An antibiotic that attacks the LPS layer would be expected to have a narrow spectrum of activity.
47)
48)
Due to its target, rifamycins can be effective over a broad spectrum.
48)
49)
Phage therapy has been used in the past as an antiviral treatment.
49)
50)
Only microbes produce antimicrobial peptides.
50)
51)
Community–acquired MRSA is typically more virulent than health care–associated MRSA.
51)
52)
Undergrowth of fungi after antibiotic use is commonly referred to as a superinfection.
52)
53)
Both trimethoprim and sulfamethoxazole inhibit reactions along the same metabolic pathway.
53)
54)
Antiviral drugs target viral processes that occur during viral infection.
54)
55)
PABA serves as the competitive inhibitor in the action of sulfanilamides.
55)
ESSAY. Write your answer in the space provided or on a separate sheet of paper.
56)
An official from an international health agency predicts that if all countries enacted legislation to only sell
antibiotics with a prescription, then the rate of antibiotic resistant would “grind to a halt.” Do you agree?
Explain.
57)
Penicillin does not directly kill bacteria. Why, then, is it considered to be bacteriocidal?
58)
Explain the difficulties in developing antiviral drugs against DNA viruses, when compared to RNA viruses.
59)
Explain why penicillin was called the “miracle drug” when it was first used in the 1940s.
60)
Can you determine both MIC and MBC from an E–test? Explain.
Answer Key
Testname: C20
18
Answer Key
Testname: C20