01 Antimicrobial Agents for Oral Infections Flashcards
What is the mechanism of action of fluconazole?
Fluconazole inhibits the fungal cytochrome P450 enzyme (14 alpha-demethylase), blocking ergosterol synthesis, a critical component of the fungal cell membrane.
What are potential adverse effects and contraindications of fluconazole?
Adverse effects: Hepatotoxicity and QT prolongation.
Contraindications: Avoid in individuals with severe hepatic impairment.
What should be considered when using fluconazole with other drugs?
Fluconazole is a CYP450 inhibitor and may interact with drugs metabolized by this enzyme, such as warfarin and phenytoin.
How do echinocandins like caspofungin, micafungin, and anidulafungin work?
They inhibit the synthesis of beta-glucan, a vital component of the fungal cell wall, causing fungal cell lysis.
What are the uses and adverse effects of echinocandins?
Uses: Treatment and prophylaxis of Candida infections.
Adverse effects: Generally well-tolerated; histamine release may occur with rapid IV infusion.
What is the mechanism of action of amphotericin B?
Amphotericin B binds to ergosterol in the fungal cell membrane, disrupting its integrity and causing cell death.
What are the adverse effects of amphotericin B?
Nephrotoxicity (kidney damage) and bone marrow suppression, leading to anemia.
How does flucytosine work, and what are its primary uses?
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.
What is nystatin used for, and how is it administered?
Uses: Treats local candidal infections, including esophageal candidiasis.
Administration: Primarily topical or as an oral suspension (swish and swallow).
What is the mechanism of action of acyclovir in HSV treatment?
Acyclovir inhibits viral DNA polymerase after phosphorylation by viral thymidine kinase, preventing viral DNA replication.
What are the toxicities and contraindications of acyclovir?
Toxicity: Rare nephrotoxicity and potential neurotoxicity at high doses.
Contraindications: Caution in patients with renal impairment.
How does valacyclovir compare to acyclovir?
Valacyclovir is a prodrug of acyclovir with better bioavailability, similar toxicity, and drug interaction profiles.
What is the mechanism of action of amoxicillin and clavulanic acid?
Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins.
Clavulanic acid is a beta-lactamase inhibitor that protects amoxicillin from degradation.
What are the side effects and contraindications of amoxicillin ± clavulanic acid?
Side effects: GI upset and hypersensitivity reactions.
Contraindications: Not for individuals with a penicillin allergy.
How does clindamycin work, and what are its associated risks?
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.
What is the mechanism of action of metronidazole?
Metronidazole forms free radicals in anaerobic bacteria, damaging their DNA and causing cell death.
What are the side effects and contraindications of metronidazole?
Side effects: Metallic taste and disulfiram-like reaction with alcohol.
Contraindications: Avoid alcohol during treatment.
What is trench mouth, and how is it treated?
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).
What is a significant resistance mechanism for fluconazole?
Resistance can develop with prolonged or repeated use due to fungal adaptations.
What makes echinocandins a better choice in some Candida infections compared to azoles?
Resistance to echinocandins is less common compared to azoles like fluconazole.
Why is amphotericin B considered a broad-spectrum antifungal?
It is effective against a wide range of fungi, including Candida, Histoplasma, Cryptococcus neoformans, Coccidioides, Aspergillus, and Blastomyces dermatitidis.
Why is nystatin primarily used topically?
Its systemic use is limited by high toxicity.
What are the primary adverse effects of amphotericin B?
Nephrotoxicity (kidney damage).
Bone marrow suppression, causing anemia.
Which fungal infections is flucytosine particularly effective against?
Candida infections and Cryptococcus neoformans.
