Question 1

Which of the following best describes selective toxicity in antimicrobial therapy?

Accepted Answer

The ability of a drug to target and kill or inhibit harmful microorganisms without causing significant damage to the host’s cells.

Question 2

Penicillin is an antibiotic that prevents the synthesis of which bacterial structure?

Accepted Answer

Peptidoglycan

Question 3

Which of the following is NOT a major action mode of antibacterial drugs as shown in Figure 20.2?

Accepted Answer

Inhibition of viral entry

Question 4

Sulfonamides are bacteriostatic drugs. What is their primary mechanism of action?

Accepted Answer

Inhibition of essential metabolite synthesis

Question 5

Why is it more difficult to achieve selective toxicity with antifungal drugs compared to antibacterial drugs?

Accepted Answer

Fungi are biologically closer to humans, so there are fewer safe drug targets.

Question 6

Acyclovir is an antiviral drug that mimics which nucleoside and blocks viral replication?

Accepted Answer

Deoxyguanosine

Question 7

Which enzyme produced by Staphylococcus bacteria breaks open the β-lactam ring of penicillin, rendering it ineffective?

Accepted Answer

Penicillinase

Question 8

The combination of trimethoprim and sulfamethoxazole (TMP-SMZ) is an example of drug synergism. What does drug synergism mean?

Accepted Answer

Two drugs work together and produce a stronger combined effect than either drug alone.

Question 9

How do bacteria become resistant to antibiotics? Select the most comprehensive answer.

Accepted Answer

By blocking entry, inactivation by enzymes, alteration of target molecule, and efflux of antibiotic.

Question 10

According to Figure 20.21, what happens to the bacterial population after the emergence of antibiotic-resistant mutants during therapy?

Accepted Answer

The population decreases and then increases as resistant mutants replace the sensitive bacteria.

Question 11

Which of the following is a real-world example of misuse of antibiotics that can lead to resistance?

Accepted Answer

Taking antibiotics for viral infections.

Question 12

Which bacterial species is the cause of gas gangrene, and what is a key feature of its infection?

Accepted Answer

Clostridium perfringens; death of soft tissue and foul odor.

Question 13

Which of the following equations best represents the exponential growth of bacteria in the absence of antibiotics?

Accepted Answer

$$N(t) = N_0$ e$$^{rt}$$

Question 14

Which part of the urinary system is usually sterile?

Accepted Answer

Urinary bladder

Question 15

What is the primary reason only a few microbial species survive inside the stomach?

Accepted Answer

Highly acidic environment

Question 16

Which bacterial species is the cause of most dental cavities, and why do dentists recommend avoiding sugary foods?

Accepted Answer

Streptococcus mutans; converts sucrose to lactic acid which dissolves tooth enamel.

Question 17

Which of the following is a protozoan disease transmitted via contaminated water and produces cysts that survive stomach acid?

Accepted Answer

Amebiasis (caused by Entamoeba histolytica)

Question 18

Which equation best describes the relationship between antibiotic resistance and time, as shown in Figure 20.21?

Accepted Answer

$$R(t) = R_0$ + kt$$

Question 19

Which of the following is a correct description of the life cycle of Echinococcus spp. (tapeworm) as shown in Figure 12.28?

Accepted Answer

Eggs are released by adult tapeworm, ingested by intermediate host, larvae migrate to liver or lungs, definitive host eats intermediate host and ingests cysts.

Comprehensive Study Notes: Antimicrobial Drugs, Microbial Diseases, and Host Systems

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