Chapter 20 Antimicrobial Drugs

25 July 2022
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A) It was the first antibiotic.
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1) Penicillin was considered a "miracle drug" for all of the following reasons EXCEPT A) It was the first antibiotic. B) It doesn't affect eukaryotic cells. C) It inhibits gram-positive cell wall synthesis. D) It has selective toxicity. E) It kills bacteria.
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C) Fungi
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2) A drug that inhibits mitosis, such as griseofulvin, would be more effective against A) Gram-positive bacteria. B) Gram-negative bacteria. C) Fungi. D) Wall-less bacteria. E) Mycobacteria.
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B) Bacteria.
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3) Most of the available antimicrobial agents are effective against A) Viruses. B) Bacteria. C) Fungi. D) Protozoa. E) All of the above.
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B) Disrupting the plasma membrane.
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4) 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. Answer:
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E) Both are based on ฮฒ-lactam.
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5) In what way are semisynthetic penicillins and natural penicillins alike? A) Both are broad spectrum. B) Both are resistant to penicillinase. C) Both are resistant to stomach acids. D) Both are bactericidal. E) Both are based on ฮฒ-lactam.
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C) Polyenes
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6) Which of the following antibiotics is NOT bactericidal? A) Aminoglycosides B) Cephalosporins C) Polyenes D) Rifampins E) Penicillin
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E) Streptomycin
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7) Which one of the following does NOT belong with the others? A) Bacitracin B) Cephalosporin C) Monobactam D) Penicillin E) Streptomycin
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B) Prevent peptide bond formation.
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8) 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.
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C) Prevent polypeptide elongation in eukaryotes.
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9) The antibiotic cycloheximide binds to the 60S subunit of the ribosome as shown in Figure 20.2. The effect is to A) Prevent mRNAribosome binding in eukaryotes. B) Prevent peptide bond formation in prokaryotes. C) Prevent polypeptide elongation in eukaryotes. D) Prevent transcription in prokaryotes. E) Prevent ribosome formation in bacteria.
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C) Penicillin
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10) Which of these antimicrobial agents has the fewest side effects? A) Streptomycin B) Tetracycline C) Penicillin D) Erythromycin E) Chloramphenicol
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C) Streptomycin
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11) Which of the following drugs does NOT act by competitive inhibition? A) Ethambutol B) Isoniazid C) Streptomycin D) Sulfonamide E) Tetracycline
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B) Inhibition of RNA synthesis
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12) 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) Competitive inhibition with DNA gyrase
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E) Polymyxin
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13) Which of the following antibiotics is recommended for use against gram-negative bacteria? A) Polyenes B) Bacitracin C) Cephalosporin D) Penicillin E) Polymyxin
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A) Amphotericin B
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14) Which of the following antimicrobial agents is recommended for use against fungal infections? A) Amphotericin B B) Bacitracin C) Cephalosporin D) Penicillin E) Polymyxin
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A) Prevent attachment of tRNA.
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18) The antibiotic chloramphenicol 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) Prevent polypeptide formation in eukaryotes.
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A) Cause misreading of mRNA in 70S ribosomes.
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19) 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) Prevent binding of tRNA in eukaryotes.
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C) Flucytosine
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20) Which compound would be the most useful to treat candidiasis? A) Uracil B) Thymine C) Flucytosine D) Guanine E) Penicillin
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B) 3 and 4
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21) 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
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B) Macrolides
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22) Which of the following antibiotics does NOT interfere with cell wall synthesis? A) Cephalosporins B) Macrolides C) Natural penicillins D) Semisynthetic penicillins E) Vancomycin
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E) Tetracyclines.
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23) The antimicrobial drugs with the broadest spectrum of activity are A) Aminoglycosides. B) Chloramphenicol. C) Lincomycin. D) Macrolides. E) Tetracyclines.
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D) Interferon inhibits glycolysis.
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24) 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) Azoles inhibit plasma membrane synthesis.
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A) Their cells are structurally and functionally similar to human cells.
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25) 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 don't have ribosomes. D) They don't reproduce. E) They have more genes than bacteria.
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B) Streptococcus pyogenes
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26) 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
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D) It is found only in gram-negative bacteria.
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27) Which of the following statements about drug resistance is false? 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.
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C) Two are always twice as effective as one.
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28) Which of the following does NOT constitute an advantage of using two antibiotics together? A) It can prevent drug resistance. B) It lessens the toxicity of individual drugs. C) Two are always twice as effective as one. D) It allows treatment to be provided prior to diagnosis. E) All of the above are advantages.
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B) When antibiotics are used indiscriminately.
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29) 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.
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B) Ethambutol - inhibits mycolic acid synthesis
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33) 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
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C) It undergoes osmotic lysis.
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34) 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) Its contents leak out.
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B) Azole antibiotics.
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35) Lamisil is an allylamine used to treat dermatomycoses. Lamisil's method of action is similar to that of A) Polymyxin B. B) Azole antibiotics. C) Echinocandins. D) Griseofulvin. E) Bacitracin.
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C) Helminths.
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36) 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.
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D) They are too dangerous to use.
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38) Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA polymerase is false? A) They cause mutations. B) They are used against viral infections. C) They can affect host cell DNA. D) They are too dangerous to use. E) They interfere with protein synthesis.
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E) Semisynthetic penicillins
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41) Which of the following does NOT affect eukaryotic cells? A) Antiprotozoan drugs B) Antihelminthic drugs C) Antifungal drugs D) Nucleotide analogs E) Semisynthetic penicillins
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A) Bacteria.
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42) 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.
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A) Aminoglycoside - changes shape of 30S units
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43) 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
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A) Transcription.
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44) 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.
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D) The antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.
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45) 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.