Question 1

Which of the following mechanisms is NOT a primary target of antimicrobial drugs?

Accepted Answer

Enhancement of microbial metabolism

Question 2

A physician prescribes a broad-spectrum antibiotic to a patient. What is a potential risk associated with this choice?

Accepted Answer

Secondary or superinfections due to killing of normal flora

Question 3

Which test is used to determine the lowest concentration of an antimicrobial that inhibits visible growth of a microorganism?

Accepted Answer

Minimum inhibitory concentration (MIC) test

Question 4

Pleconaril is an example of an antimicrobial drug that acts by:

Accepted Answer

Blocking viral attachment to host cells

Question 5

Why is it incorrect to say that an individual bacterium develops resistance in response to an antibiotic?

Accepted Answer

Resistance arises from mutations or gene acquisition in populations, not individual adaptation

Question 6

Which of the following is a characteristic of an ideal antimicrobial agent?

Accepted Answer

Selectively toxic against a wide range of pathogens

Question 7

A patient develops 'black hairy tongue' after taking metronidazole. This is an example of:

Accepted Answer

A side effect due to drug toxicity

Question 8

Which mechanism allows Mycobacterium tuberculosis to resist fluoroquinolone drugs?

Accepted Answer

Production of MfpA protein that binds DNA gyrase

Question 9

If a drug has a therapeutic index (TI) defined as $$ TI = \frac{TD_{50}}{ED_{50}} $$, what does a high TI indicate?

Accepted Answer

The drug is safe, with a wide margin between effective and toxic doses

Question 10

Which route of administration provides the most rapid and highest blood levels of an antimicrobial agent?

Accepted Answer

Intravenous administration

Question 11

A hospital-acquired pathogen is resistant to penicillin, tetracycline, and erythromycin. This organism is classified as:

Accepted Answer

Multiple-drug-resistant

Question 12

Which of the following is a reason why physicians do NOT always prescribe the antimicrobial with the largest zone of inhibition in a diffusion susceptibility test?

Accepted Answer

Other factors such as toxicity, patient allergies, and pharmacokinetics must be considered

Question 13

Which of the following is a method by which bacteria can acquire resistance to antimicrobial drugs?

Accepted Answer

Acquisition of R plasmids via conjugation

Question 14

Which of the following best describes synergism in antimicrobial therapy?

Accepted Answer

Two drugs together have a greater effect than either alone

Question 15

A patient develops a secondary infection after broad-spectrum antibiotic therapy. What is the most likely cause?

Accepted Answer

Overgrowth of resistant normal flora

Question 16

Which of the following drugs acts by inhibiting cell wall synthesis?

Accepted Answer

Penicillin

Question 17

Which of the following is a plausible consequence of killing normal flora with broad-spectrum antibiotics?

Accepted Answer

Development of superinfections

Question 18

Which of the following mechanisms of resistance involves pumping the antimicrobial drug out of the cell before it can act?

Accepted Answer

Efflux pumps

Question 19

Which of the following strategies can help retard the development of antimicrobial resistance?

Accepted Answer

Using antimicrobials only when necessary

Question 20

A new antimicrobial drug is designed to be complementary to the shape of a microbial protein. This approach is most likely to:

Accepted Answer

Inhibit the function of the target protein

Controlling Microbial Growth in the Body: Antimicrobial Drugs – Mechanisms, Selection, and Effectiveness

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