Antifungal Drugs Practice Questions
18 free Antifungal Drugs practice questions for the Microbiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which antifungal drug binds to ergosterol in fungal cell membranes and forms pores leading to cell death?
- A Amphotericin B
- B Fluconazole
- C Griseofulvin
- D Ciclopirox olamine
Correct answer: Amphotericin B
Amphotericin B binds ergosterol in the fungal cell membrane and forms pores that increase membrane permeability. Leakage of intracellular ions and small molecules follows, killing the fungal cell.
Which antifungal drug class inhibits ergosterol synthesis by blocking the enzyme lanosterol 14-alpha-demethylase?
- A Azole antifungals
- B Polyene antifungals
- C Echinocandins
- D Allylamines
Correct answer: Azole antifungals
Azoles such as fluconazole and ketoconazole inhibit the fungal cytochrome P450 enzyme lanosterol 14-alpha-demethylase. Ergosterol synthesis is blocked and the fungal cell membrane loses its integrity.
Which antifungal drug is mainly used topically for oral candidiasis (thrush)?
- A Intravenous amphotericin B
- B Oral fluconazole
- C Oral griseofulvin
- D Nystatin oral suspension
Correct answer: Nystatin oral suspension
Nystatin is a polyene too toxic to give systemically, so it is used as an oral suspension that is held in the mouth and then swallowed, acting topically on the mucosa. It binds ergosterol and disrupts the Candida cell membrane locally. Amphotericin B is the systemic polyene, fluconazole is a systemic azole used for oesophageal or resistant disease, and griseofulvin treats dermatophytes and has no activity against Candida.
Which antifungal drug interferes with fungal microtubule function and inhibits mitosis?
- A Ketoconazole
- B Amphotericin B
- C Caspofungin
- D Griseofulvin
Correct answer: Griseofulvin
Griseofulvin disrupts fungal microtubule function and inhibits mitosis. It is mainly used to treat dermatophyte infections of the skin, hair, and nails.
Which antifungal drug class inhibits beta-glucan synthesis in the fungal cell wall?
- A Azole antifungals
- B Polyenes
- C Allylamines
- D Echinocandins
Correct answer: Echinocandins
Echinocandins such as caspofungin inhibit the synthesis of beta-1,3-D-glucan, an essential structural polymer of the fungal cell wall. The weakened wall cannot resist osmotic stress and the fungal cell dies.
Which antifungal drug is an echinocandin used for invasive Candida infections?
- A Ketoconazole
- B Terbinafine
- C Nystatin
- D Caspofungin
Correct answer: Caspofungin
Caspofungin belongs to the echinocandin class and inhibits fungal cell wall synthesis. It is used for invasive candidiasis and some Aspergillus infections.
Which antifungal drug commonly causes nephrotoxicity as a major adverse effect?
- A Terbinafine
- B Clotrimazole
- C Undecylenic acid
- D Amphotericin B
Correct answer: Amphotericin B
Amphotericin B also binds cholesterol in human cell membranes, and renal tubular cells are especially susceptible, so azotaemia, potassium wasting and magnesium wasting are common. Renal function and electrolytes must be monitored, and liposomal preparations reduce this toxicity.
Which antifungal drug inhibits the enzyme squalene epoxidase in fungal cells?
- A Fluconazole
- B Amphotericin B
- C Terbinafine
- D Nystatin
Correct answer: Terbinafine
Terbinafine inhibits the enzyme squalene epoxidase, which is involved in ergosterol synthesis. This leads to accumulation of toxic squalene and fungal cell death.
Which antifungal drug is commonly used for treatment of dermatophyte infections such as ringworm?
- A Amphotericin B
- B Caspofungin
- C Terbinafine
- D Flucytosine
Correct answer: Terbinafine
Terbinafine is commonly used to treat dermatophyte infections such as ringworm and athlete's foot. It interferes with ergosterol synthesis by inhibiting squalene epoxidase.
Which antifungal drug is converted inside fungal cells into a compound that inhibits DNA and RNA synthesis?
- A Fluconazole
- B Amphotericin B
- C Flucytosine
- D Terbinafine
Correct answer: Flucytosine
Flucytosine is converted within fungal cells into 5-fluorouracil, which interferes with nucleic acid synthesis. This disrupts fungal cell growth and replication.
Which fungal cell membrane component is the main target of many antifungal drugs?
- A Chitin
- B Beta-glucan
- C Ergosterol
- D Cholesterol
Correct answer: Ergosterol
Ergosterol is the principal sterol of the fungal cell membrane, the role cholesterol plays in human membranes. Polyenes bind it directly and azoles and allylamines block its synthesis, while chitin and beta-glucan belong to the cell wall, not the membrane.
Which antifungal drug is often used intravenously for severe systemic fungal infections?
- A Griseofulvin
- B Amphotericin B
- C Terbinafine
- D Potassium iodide
Correct answer: Amphotericin B
Amphotericin B is given by slow intravenous infusion for life-threatening systemic mycoses and has the broadest antifungal spectrum of the available agents. Griseofulvin, terbinafine and potassium iodide are taken orally for superficial or subcutaneous infections instead.
Which antifungal drug is commonly used topically for athlete's foot?
- A Amphotericin B
- B Clotrimazole
- C Caspofungin
- D Flucytosine
Correct answer: Clotrimazole
Clotrimazole is a topical azole antifungal used to treat superficial fungal infections such as athlete's foot and ringworm.
Which fungal infection primarily affects the skin, hair, and nails?
- A Dermatophytosis
- B Candidiasis
- C Histoplasmosis
- D Cryptococcal meningitis
Correct answer: Dermatophytosis
Dermatophytosis is caused by dermatophytes, which invade keratinized tissues such as the skin, hair, and nails. Candidiasis mainly involves mucosal surfaces, histoplasmosis is primarily pulmonary, and cryptococcal infection classically involves the central nervous system.
Which antifungal drug has activity against Aspergillus species?
- A Voriconazole
- B Nystatin
- C Tolnaftate
- D Griseofulvin
Correct answer: Voriconazole
Voriconazole is an azole antifungal effective against Aspergillus infections. It inhibits ergosterol synthesis in fungal cell membranes.
Which mechanism explains how echinocandins kill fungal cells?
- A Inhibition of fungal cell wall synthesis
- B Inhibition of fungal DNA transcription
- C Disruption of mitochondrial membrane potential
- D Binding to ergosterol in the cell membrane
Correct answer: Inhibition of fungal cell wall synthesis
Echinocandins inhibit the synthesis of beta-glucan, an essential component of the fungal cell wall. The weakened wall can no longer withstand osmotic pressure, causing cell lysis. Binding to ergosterol in the membrane is the mechanism of amphotericin B, not the echinocandins.
Which adverse effect is commonly associated with azole antifungal drugs?
- A Liver toxicity
- B Kidney stones
- C Bone fractures
- D Hearing loss
Correct answer: Liver toxicity
Azole antifungals can cause hepatotoxicity due to their effects on liver enzymes. Liver function tests are often monitored during therapy.
What is the primary therapeutic goal of antifungal drug therapy?
- A Suppress the host immune response to fungal antigens
- B Inhibit or kill fungi while sparing host cells
- C Eliminate the gut bacteria that compete with fungi
- D Neutralize circulating fungal toxins
Correct answer: Inhibit or kill fungi while sparing host cells
Antifungal drugs exploit targets that are unique to fungi, such as ergosterol in the cell membrane or beta-glucan in the cell wall. This selective toxicity lets the drug inhibit or kill the fungus while causing as little damage as possible to human cells.