Q: Which of the following equations correctly represents the calculation of the therapeutic index (TI) for an antimicrobial drug?

$$TI = \frac{\text{Toxic Dose}}{\text{Therapeutic Dose}}$$

Question 1

Which scientist is credited with the discovery of penicillin, and what was the source organism?

Accepted Answer

Alexander Fleming; Penicillium chrysogenum

Question 2

Which of the following best describes the principle of selective toxicity?

Accepted Answer

A drug that targets microbial structures or functions not found in the host

Question 3

Which of the following drugs acts by inhibiting the synthesis of mycolic acid in mycobacterial species?

Accepted Answer

Isoniazid

Question 4

A patient is prescribed a drug that blocks the transport of NAG and NAM from the cytoplasm. Which drug is most likely being used?

Accepted Answer

Bacitracin

Question 5

Which of the following statements about beta-lactam antibiotics is correct?

Accepted Answer

They prevent cross-linkage of NAM subunits in peptidoglycan.

Question 6

Which of the following is a semisynthetic antibiotic, and what is a key advantage of semisynthetics?

Accepted Answer

Methicillin; more stable in acidic environments

Question 7

Which of the following drugs interferes with the charging of tRNA molecules by binding to isoleucyl-tRNA synthetase?

Accepted Answer

Mupirocin

Question 8

A patient develops kidney toxicity after receiving an antimicrobial drug for a Gram-negative infection. Which drug is most likely responsible?

Accepted Answer

Polymyxin

Question 9

Which of the following best explains why broad-spectrum antibiotics can lead to superinfections?

Accepted Answer

They kill normal flora, reducing microbial antagonism.

Question 10

Which test combines aspects of the Kirby-Bauer diffusion susceptibility test and the MIC test to determine the minimum inhibitory concentration of a drug?

Accepted Answer

Etest

Question 11

Which of the following equations correctly represents the calculation of the therapeutic index (TI) for an antimicrobial drug?

Accepted Answer

$$TI = \frac{	ext{Toxic Dose}}{	ext{Therapeutic Dose}}$$

Question 12

Which of the following mechanisms is NOT a way bacteria can resist antimicrobial drugs?

Accepted Answer

Increasing uptake of the drug into the cell

Question 13

A hospital-acquired pathogen is resistant to three different classes of antibiotics. What is the best term to describe this organism?

Accepted Answer

Multiple-drug-resistant

Question 14

Which of the following is a real-world example of synergism in antimicrobial therapy?

Accepted Answer

Using penicillin and aminoglycoside together to treat endocarditis

Question 15

Which of the following statements about antiviral drugs is correct?

Accepted Answer

They often target unique aspects of viral metabolism, such as reverse transcriptase.

Question 16

Which of the following best describes the action of sulfonamides?

Accepted Answer

They act as analogs of para-aminobenzoic acid (PABA), inhibiting folic acid synthesis.

Question 17

Which of the following is a major concern when prescribing antibiotics to pregnant women?

Accepted Answer

Potential toxicity to the fetus

Question 18

Which of the following is a correct statement about the difference between antibiotics and synthetic antimicrobials?

Accepted Answer

Antibiotics are produced naturally by organisms, while synthetics are completely synthesized in the lab.

Question 19

Which of the following is a possible consequence of disrupting the normal microbiota with broad-spectrum antibiotics?

Accepted Answer

Development of secondary infections

Question 20

Which of the following best describes the mechanism of action of amphotericin B?

Accepted Answer

It binds to ergosterol, forming pores in fungal membranes.

Ch 10 - Controlling Microbial Growth in the Body: Antimicrobial Drugs

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