TI = $$\frac{\text{dose that produces toxic effect}}{\text{dose that produces therapeutic effect}}$$

Question 1

Which scientist is credited with discovering the first antibiotic, and what organism produced it?

Accepted Answer

Alexander Fleming; Penicillium chrysogenum

Question 2

What is the principle of selective toxicity in antimicrobial therapy?

Accepted Answer

Drugs should target only pathogens without harming host cells

Question 3

Which of the following drugs inhibits cell wall synthesis by preventing cross-linkage of NAM subunits?

Accepted Answer

Penicillin

Question 4

Why are beta-lactam antibiotics ineffective against non-growing bacterial cells?

Accepted Answer

Non-growing cells do not synthesize new peptidoglycan

Question 5

Which antimicrobial drug disrupts fungal cytoplasmic membranes by binding to ergosterol?

Accepted Answer

Amphotericin B

Question 6

A patient is prescribed a drug that inhibits folic acid synthesis in bacteria. Which class of drugs is most likely being used?

Accepted Answer

Sulfonamides

Question 7

Which of the following best describes the mechanism of action of tetracycline?

Accepted Answer

Blocks docking site of tRNA on the 30S ribosomal subunit

Question 8

Which test is used to determine the minimum concentration of an antimicrobial drug required to inhibit visible growth of a microorganism?

Accepted Answer

Minimum inhibitory concentration (MIC) test

Question 9

What is the therapeutic index (TI) of a drug, and how is it calculated?

Accepted Answer

TI = $$\frac{	ext{dose that produces toxic effect}}{	ext{dose that produces therapeutic effect}}$$

Question 10

Which route of administration achieves the highest and most consistent concentration of drug in the blood?

Accepted Answer

Continuous intravenous

Question 11

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

Accepted Answer

The antibiotic killed normal flora, reducing microbial antagonism

Question 12

Which mechanism allows bacteria to rapidly acquire resistance to multiple drugs?

Accepted Answer

Acquisition of R plasmids via transformation, transduction, or conjugation

Question 13

Which of the following is an example of cross resistance?

Accepted Answer

Resistance to several drugs with similar structures, such as all beta-lactams

Question 14

What is the effect of beta-lactamase production in bacteria?

Accepted Answer

Destroys the beta-lactam ring, inactivating the antibiotic

Question 15

Which antimicrobial drug is most likely to cause toxicity to human kidneys?

Accepted Answer

Polymyxin

Question 16

A patient with HIV is treated with a drug that inhibits reverse transcriptase. Why does this drug not harm human cells?

Accepted Answer

Human cells lack reverse transcriptase

Question 17

Which of the following is a clinical consideration when prescribing antimicrobial drugs?

Accepted Answer

Spectrum of action

Question 18

What is the main advantage of using synergistic combinations of antimicrobial drugs?

Accepted Answer

One drug enhances the effect of the other, increasing efficacy

Question 19

Which of the following is NOT a mechanism of microbial resistance to antimicrobial drugs?

Accepted Answer

Increased uptake of drugs

Question 20

Which antimicrobial drug is produced by Streptomyces griseus and is effective against Mycobacterium tuberculosis?

Accepted Answer

Streptomycin

Ch 10 Controlling Microbial Growth in the Body: Antimicrobial Drugs

Study Guide - Practice Questions