Question 1

Which of the following antibiotics disrupts cytoplasmic membrane function?

Accepted Answer

Amphotericin B disrupts cytoplasmic membrane function by binding to ergosterol, a component of fungal and certain bacterial cell membranes.

Question 2

Another term for the Kirby-Bauer test is the

Accepted Answer

The Kirby-Bauer test is also known as the diffusion susceptibility test. The other options refer to different types of antibiotic susceptibility tests.

Question 3

β-lactamase production is an example of which of the following types of resistance?

Accepted Answer

β-lactamase is an enzyme that inactivates β-lactam antibiotics, such as penicillins and cephalosporins, by breaking the β-lactam ring structure. Therefore, β-lactamase production represents inactivation of the drug.

Question 4

Which of the following statements about the zone of inhibition is FALSE?

Accepted Answer

The larger the zone, the more susceptible the organism is to the drug being tested, not resistant.

Question 5

The most limited group of antimicrobial agents is the __________ drugs.

Accepted Answer

Antiviral drugs are the most limited group of antimicrobial agents due to the unique characteristics of viruses, including the lack of a cell wall or membrane and the ability to mutate rapidly. These factors make it difficult to find drugs that specifically target and kill viruses without harming the host cells.

Question 6

A large percentage of antibiotics and semisynthetic drugs are produced by members of the genus

Accepted Answer

Streptomyces is a genus of bacteria that is known for its ability to produce a wide variety of antibiotics and semisynthetic drugs. In fact, it is estimated that more than two-thirds of all antibiotics are produced by Streptomyces species. Therefore, E is the best choice.

Question 7

Beta-lactam antibiotics have an effect on which of the following types of cells?

Accepted Answer

Beta-lactam antibiotics have an effect on bacterial cells by inhibiting the synthesis of peptidoglycan in the cell wall, which ultimately leads to bacterial cell death. They do not have an effect on animal, fungal, or virus-infected cells as these cells do not have peptidoglycan in their cell walls.

Question 8

Which of the following statements concerning development of antibiotic resistance is FALSE?

Accepted Answer

Resistant cells do not necessarily grow more efficiently and quickly than susceptible cells. In fact, mutations or acquisition of resistance genes may come with a fitness cost, meaning that resistant cells may grow more slowly or less efficiently than susceptible cells in certain environments.

Question 9

Most broad-spectrum antibiotics act by

Accepted Answer

Broad-spectrum antibiotics typically inhibit protein synthesis by targeting bacterial ribosomes. This mode of action is effective against a wide range of bacterial species, as ribosomes are a universal target in prokaryotic cells. Examples of broad-spectrum antibiotics that work by inhibiting protein synthesis include tetracyclines and macrolides.

Question 10

Sulfonamides

Accepted Answer

Sulfonamides were the first widely used antimicrobial drugs and indirectly inhibit nucleic acid synthesis.

Question 11

Which of the following is a primary advantage of semisynthetic drugs?

Accepted Answer

Semisynthetic drugs have a broader spectrum of action than either natural or synthetic drugs. By modifying a natural compound, scientists can create a semisynthetic drug that can target a wider range of microorganisms or diseases. This gives these drugs a versatility that is difficult to achieve with natural or synthetic compounds alone.

Question 12

An antimicrobial that inhibits cell wall synthesis will result in which of the following?

Accepted Answer

Antimicrobials that inhibit cell wall synthesis disrupt the integrity of the cell wall, making cells more susceptible to osmotic pressure. This can lead to lysis of the cell.

Question 13

Which of the following can result when antibiotic therapy disrupts the normal microbiota?

Accepted Answer

Antibiotic therapy can disrupt the normal microbiota, leading to the overgrowth of opportunistic pathogens such as Candida albicans, which can cause thrush, and Clostridioides difficile, which can cause pseudomembranous colitis. Anaphylactic shock is a severe allergic reaction that is not directly related to disruption of the normal microbiota. Black hairy tongue is a condition that can be caused by several factors, including poor oral hygiene and the use of some medications, but is typically not associated with antibiotic therapy.

Question 14

Probiotics

Accepted Answer

The answer of Probiotics
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Question 15

Which scientist coined the term antibiotic?

Accepted Answer

Selman Waksman coined the term "antibiotic" to describe compounds produced by microorganisms that inhibit the growth of other microorganisms.

Question 16

Most drugs that inhibit the synthesis of the cell wall act by

Accepted Answer

Drugs that inhibit the synthesis of the cell wall, such as penicillins and cephalosporins, work by preventing the cross-linkage of NAM subunits. This leads to weakened cell walls and ultimately cell lysis.

Question 17

Which of the following groups of drugs can become incorporated into the bones and teeth of a fetus?

Accepted Answer

Tetracyclines are the only group of drugs listed that can become incorporated into the bones and teeth of a fetus. This can lead to discoloration and weakened enamel in the infant's teeth. Therefore, tetracyclines should be avoided during pregnancy.

Question 18

Which of the following antifungals works by inhibiting ergosterol synthesis?

Accepted Answer

Both fluconazole and turbinafine work by inhibiting ergosterol synthesis. Fluconazole inhibits the enzyme lanosterol 14-alpha-demethylase, which is involved in the conversion of lanosterol to ergosterol. Turbinafine inhibits squalene epoxidase, which is involved in the conversion of squalene to lanosterol, ultimately inhibiting ergosterol synthesis. Amphotericin B and nystatin work by binding to ergosterol and disrupting fungal cell membrane function.

Question 19

Which of the following is NOT a target of drugs that inhibit protein synthesis?

Accepted Answer

Drugs that inhibit protein synthesis target various aspects of ribosomes and the protein synthesis process. Alanine-alanine bridges are not directly involved in protein synthesis, making option B the correct answer. The other options are all targets of drugs that inhibit protein synthesis.

Question 20

Which of the following drugs specifically targets cell walls that contain arabinogalactan-mycolic acid?

Accepted Answer

Isoniazid specifically targets cell walls that contain arabinogalactan-mycolic acid, which is unique to mycobacteria such as Mycobacterium tuberculosis. Vancomycin targets the cell walls of Gram-positive bacteria, while penicillin and methicillin target the cell walls of bacteria that have peptidoglycan. Bacitracin targets the cell membrane of bacteria.

Quiz 10: Controlling Microbial Growth in the Body: Antimicrobial Drugs