Ch. 15 - Antimicrobial Drugs

Norman-McKay- Microbiology: Basic and Clinical Principles 2nd Edition

Norman-McKay2nd EditionMicrobiology: Basic and Clinical PrinciplesISBN: 9780137661619Not the one you use?Change textbook

Norman-McKay 2nd Edition

Ch. 15 - Antimicrobial Drugs

Problem 16

Chapter 15, Problem 16

Choose the false statement(s). Select all that apply.
a. Antifungal drugs may target cholesterol in fungal cell membranes.
b. Azole and polyene drugs promote cell lysis by impacting fungal cell plasma membranes.
c. Echinocandin drugs inhibit fungal cell wall synthesis.
d. Antifungal drugs may target DNA replication.
e. Antifungal drugs may target protein synthesis.

Verified step by step guidance

Step 1: Understand the target structures and processes of antifungal drugs. Antifungal drugs typically target components unique to fungi, such as ergosterol in the fungal cell membrane or the fungal cell wall, which contains glucans and chitin.

Step 2: Evaluate statement (a). Cholesterol is a component of animal cell membranes, while fungi have ergosterol instead. Therefore, antifungal drugs target ergosterol, not cholesterol, in fungal membranes. This suggests statement (a) is false.

Step 3: Evaluate statement (b). Azoles inhibit ergosterol synthesis, and polyenes bind to ergosterol, disrupting fungal plasma membranes and causing cell lysis. This is a true statement.

Step 4: Evaluate statement (c). Echinocandins inhibit the synthesis of β-glucan, an essential component of the fungal cell wall, making this statement true.

Step 5: Evaluate statements (d) and (e). Antifungal drugs generally do not target DNA replication or protein synthesis directly, as these processes are similar in fungi and human cells, making selective targeting difficult. Therefore, these statements are false.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Fungal Cell Membrane Composition

Fungal cell membranes contain ergosterol, not cholesterol, which is a key target for many antifungal drugs. Drugs like azoles and polyenes disrupt ergosterol synthesis or bind to ergosterol, compromising membrane integrity and causing cell death.

Mechanism of Action of Antifungal Drug Classes

Azoles inhibit ergosterol synthesis, polyenes bind ergosterol causing membrane pores, and echinocandins inhibit β-glucan synthesis in the fungal cell wall. These mechanisms disrupt essential fungal structures, leading to cell lysis or growth inhibition.

Targets of Antifungal Drugs Beyond Membranes and Cell Walls

Unlike some antibacterial agents, most antifungal drugs do not target DNA replication or protein synthesis. Their primary targets are fungal-specific components like ergosterol and cell wall glucans, making statements about DNA or protein synthesis targeting generally false.

Recommended video:

Guided course

02:44

Types of Bacterial Cell Walls

Related Practice

Textbook Question

Mark the following as true or false, and then correct the false statements so they are true.

a. Human cells make drug efflux pumps.

b. The minimum bactericidal concentration is the minimum concentration of the drug that kills at least 50 percent of the bacteria present.

c. The E-test can reveal if a drug is bactericidal or bacteriostatic.

d. A drug that is bactericidal at one dose may be bacteriostatic at another dose.

e. The antifolate combination therapy trimethoprim-sulfamethoxazole may be used to treat protozoan infections.

views

Textbook Question

Acquired antibiotic resistance can include all of the following except:

a. Altering an enzyme that a given drug may target

b. Making endospores

c. Altering a point of entry for a drug

d. Making enzymes that inactivate a drug

e. Increasing the number of efflux pumps that are active in a cell

views

Textbook Question

Why is it challenging to obtain selectively toxic drugs against fungi, protozoans, and viruses?

views

Textbook Question

Which sensitivity test is best for determining the minimum bactericidal concentration and the minimum inhibitory concentration of a drug?

views

Textbook Question

Match the antimicrobial drug to its feature. Some features may be used more than once, and some may not be used at all.

views