01 Antimicrobial Agents for Oral Infections

Question 1

What is the mechanism of action of fluconazole?

Answer 1

Fluconazole inhibits the fungal cytochrome P450 enzyme (14 alpha-demethylase), blocking ergosterol synthesis, a critical component of the fungal cell membrane.

Question 2

What are potential adverse effects and contraindications of fluconazole?

Answer 2

Adverse effects: Hepatotoxicity and QT prolongation.
Contraindications: Avoid in individuals with severe hepatic impairment.

Question 3

What should be considered when using fluconazole with other drugs?

Answer 3

Fluconazole is a CYP450 inhibitor and may interact with drugs metabolized by this enzyme, such as warfarin and phenytoin.

Question 4

How do echinocandins like caspofungin, micafungin, and anidulafungin work?

Answer 4

They inhibit the synthesis of beta-glucan, a vital component of the fungal cell wall, causing fungal cell lysis.

Question 5

What are the uses and adverse effects of echinocandins?

Answer 5

Uses: Treatment and prophylaxis of Candida infections.
Adverse effects: Generally well-tolerated; histamine release may occur with rapid IV infusion.

Question 6

What is the mechanism of action of amphotericin B?

Answer 6

Amphotericin B binds to ergosterol in the fungal cell membrane, disrupting its integrity and causing cell death.

Question 7

What are the adverse effects of amphotericin B?

Answer 7

Nephrotoxicity (kidney damage) and bone marrow suppression, leading to anemia.

Question 8

How does flucytosine work, and what are its primary uses?

Answer 8

Mechanism: It is a pyrimidine antimetabolite that disrupts fungal nucleic acid metabolism by being converted to 5-fluorouracil, inhibiting fungal RNA and protein synthesis.

Uses: Effective against Candida and Cryptococcus neoformans infections.

Question 9

What is nystatin used for, and how is it administered?

Answer 9

Uses: Treats local candidal infections, including esophageal candidiasis.
Administration: Primarily topical or as an oral suspension (swish and swallow).

Question 10

What is the mechanism of action of acyclovir in HSV treatment?

Answer 10

Acyclovir inhibits viral DNA polymerase after phosphorylation by viral thymidine kinase, preventing viral DNA replication.

Question 11

What are the toxicities and contraindications of acyclovir?

Answer 11

Toxicity: Rare nephrotoxicity and potential neurotoxicity at high doses.

Contraindications: Caution in patients with renal impairment.

Question 12

How does valacyclovir compare to acyclovir?

Answer 12

Valacyclovir is a prodrug of acyclovir with better bioavailability, similar toxicity, and drug interaction profiles.

Question 13

What is the mechanism of action of amoxicillin and clavulanic acid?

Answer 13

Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins.
Clavulanic acid is a beta-lactamase inhibitor that protects amoxicillin from degradation.

Question 14

What are the side effects and contraindications of amoxicillin ± clavulanic acid?

Answer 14

Side effects: GI upset and hypersensitivity reactions.
Contraindications: Not for individuals with a penicillin allergy.

Question 15

How does clindamycin work, and what are its associated risks?

Answer 15

Mechanism: Inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit.

Risks: Can cause Clostridioides difficile colitis; avoid in patients with a history of C. difficile infections.

Question 16

What is the mechanism of action of metronidazole?

Answer 16

Metronidazole forms free radicals in anaerobic bacteria, damaging their DNA and causing cell death.

Question 17

What are the side effects and contraindications of metronidazole?

Answer 17

Side effects: Metallic taste and disulfiram-like reaction with alcohol.

Contraindications: Avoid alcohol during treatment.

Question 18

What is trench mouth, and how is it treated?

Answer 18

Condition: Acute necrotizing ulcerative gingivitis (ANUG).
Treatment:
1. Antimicrobials like metronidazole, amoxicillin + clavulanic acid, or clindamycin.
2. Mechanical debridement.
3. Supportive care (pain management, oral hygiene, and dietary modifications).

Question 19

What is a significant resistance mechanism for fluconazole?

Answer 19

Resistance can develop with prolonged or repeated use due to fungal adaptations.

Question 20

What makes echinocandins a better choice in some Candida infections compared to azoles?

Answer 20

Resistance to echinocandins is less common compared to azoles like fluconazole.

Question 21

Why is amphotericin B considered a broad-spectrum antifungal?

Answer 21

It is effective against a wide range of fungi, including Candida, Histoplasma, Cryptococcus neoformans, Coccidioides, Aspergillus, and Blastomyces dermatitidis.

Question 22

Why is nystatin primarily used topically?

Answer 22

Its systemic use is limited by high toxicity.

Question 23

What are the primary adverse effects of amphotericin B?

Answer 23

Nephrotoxicity (kidney damage).
Bone marrow suppression, causing anemia.

Question 24

Which fungal infections is flucytosine particularly effective against?

Answer 24

Candida infections and Cryptococcus neoformans.

Question 25

How does resistance to acyclovir develop?

Answer 25

Through mutations in viral thymidine kinase or DNA polymerase genes.

Question 26

What are the other HSV-1 treatment drugs besides acyclovir and valacyclovir?

Answer 26

Cidofovir, famciclovir, ganciclovir, penciclovir, and foscarnet.

Question 27

What is the unique adverse effect of metronidazole when combined with alcohol?

Answer 27

A disulfiram-like reaction causing flushing, nausea, and vomiting.

Question 28

Why should caution be used when combining metronidazole with warfarin?

Answer 28

Metronidazole enhances warfarin’s effects, increasing the risk of bleeding.

Question 29

What supportive care is important in the treatment of trench mouth?

Answer 29

Pain management.
Oral hygiene instruction.
Dietary modifications.

Question 30

What makes valacyclovir more advantageous than acyclovir?

Answer 30

Its better bioavailability allows for less frequent dosing.