Questions and Answers
What is the primary mechanism by which anti-HSV drugs inhibit viral replication?
Which of the following is not a requirement for the activation of anti-HSV drugs?
Which condition requires incision and drainage as a primary treatment?
What is a common characteristic of drugs like Acyclovir and Valacyclovir?
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Which of the following statements about purulence is true?
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What is the primary mechanism by which AmpB induces cell death in fungal cells?
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Which of the following is a significant adverse effect associated with Amphotericin B?
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Why must Amphotericin B be formulated with artificial lipids for administration?
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What type of reaction can occur shortly after the intravenous administration of Amphotericin B?
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Which of the following statements about Griseofulvin is true?
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What is the primary mechanism of action of azole antifungals?
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Which azole has the greatest potential to inhibit the CYP450 3A4 isoenzyme?
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Which of the following drugs falls under the echinocandin class?
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What is a common side effect of echinocandins?
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Why should azole antifungals be avoided in pregnancy?
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What is the mechanism of action of clindamycin?
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Which of the following is a significant side effect associated with clindamycin use?
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What type of bacteria is clindamycin effective against?
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Which of the following antibiotics are aminoglycosides?
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What is a primary characteristic of aminoglycosides in terms of their killing action?
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What is a consequence of aminoglycosides’ poor tissue penetration?
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Why is dosage adjustment necessary in renal failure for aminoglycosides?
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Which of the following statements about clindamycin resistance is true?
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What is the preferred route of administration for drugs that can cause a histamine-like reaction when infused rapidly?
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Which medication is specifically indicated for patients with invasive candidiasis?
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In cases of mild oropharyngeal candidiasis, which treatment is preferred?
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What should be done for a patient with severe oropharyngeal candidiasis?
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Why are oral azoles contraindicated during the first trimester of pregnancy?
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When would oral fluconazole be an appropriate option for treating oropharyngeal candidiasis?
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Which medication options are considered effective for initial therapy in oropharyngeal candidiasis?
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Which of the following is NOT a characteristic of fluconazole as a treatment for severe disease?
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Study Notes
Lincosamides - Clindamycin
- Inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit.
- Exhibits bacteriostatic activity against Gram-positive aerobic and anaerobic bacteria.
- Resistance mechanisms include intrinsic resistance in Gram-negative bacteria and cross-resistance with macrolides.
- Pharmacokinetics: Distributed widely in tissues, including bones and abscesses, but poorly penetrates the central nervous system (CNS).
- Side effects include nausea, diarrhea, rash, contact dermatitis, impaired liver function, and neutropenia.
- C. difficile can cause antibiotic-associated colitis, necessitating treatment with metronidazole or vancomycin.
Aminoglycosides
- Bactericidal antibiotics affecting the 30S ribosomal subunit.
- Key agents: Streptomycin, neomycin, kanamycin, amikacin, gentamicin, tobramycin, sisomicin, netlicin.
- Mechanism of action involves inhibiting protein synthesis via interference with ribosomal function.
- Demonstrates concentration-dependent killing with significant post-antibiotic effects; more effective with single large doses versus multiple smaller doses.
- Pharmacokinetics: High concentration in renal cortex; poor tissue penetration; primarily excreted by the kidneys, needing dosage adjustment in renal failure.
Antivirals - Mechanism of Action for HSV
- Primarily inhibit DNA polymerase through two mechanisms:
- A: Compete with nucleotides on the substrate site—nucleoside analogues (e.g., acyclovir, valacyclovir).
- B: Require viral enzymes for phosphorylation to activate, preventing viral DNA synthesis selectively.
- Other drug actions include disruption of fungal RNA/DNA synthesis via metabolites and inhibition of mitotic cell division (e.g., griseofulvin).
- Amphotericin B binds to ergosterol in fungal cell membranes, leading to cell death, either fungicidal or fungistatic depending on concentration and organism.
Amphotericin B
- Administered via slow intravenous infusion due to low water solubility; requires lipid formulation to reduce toxicity.
- Known for a low therapeutic index with side effects including fever, chills, headaches, vomiting, and renal impairment.
- Can cause renal tubular acidosis and requires potassium supplementation due to magnesium wasting.
Azoles
- Work by inhibiting the fungal cytochrome P450 enzyme (14-α demethylase), disrupting ergosterol production and affecting fungal membrane structure.
- Contraindicated in pregnancy due to teratogenic effects; should avoid in the first trimester.
- All azoles can cause QT prolongation; some notable ones include ketoconazole, itraconazole, voriconazole, and fluconazole.
Echinocandins
- Agents: Caspofungin, micafungin, anidulafungin, which inhibit β(1,3)-D-glucan synthesis in fungal cell walls.
- Effective against Aspergillus and most resistant Candida species.
- Common side effects include fever, rash, nausea, and phlebitis; avoid rapid infusion to prevent histamine-like reactions.
Oropharyngeal Candidiasis - Initial Therapy
- Mild cases benefit from topical therapies such as clotrimazole troches or miconazole buccal tablets, which are more effective than nystatin.
- Fluconazole is favored for severe cases due to ease of administration and favorable side effect profile.
- Pregnant women should use topical therapies (e.g., clotrimazole, miconazole), avoiding oral azoles in the first trimester due to teratogenicity risks.
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Description
This quiz covers the mechanism of action of Clindamycin, a type of lincosamide, and its effects on bacterial protein synthesis. It includes information on its spectrum of activity against gram-positive bacteria, resistance mechanisms, and pharmacokinetics. Test your knowledge on this important antibiotic and its clinical implications.
