Which of the following antibiotics requires close monitoring and dosing adjustment in a patient with liver disease?

Correct Answer: C

Rationale: The correct answer is C: Vancomycin. Vancomycin requires close monitoring and dosing adjustment in patients with liver disease because it is primarily eliminated by the kidneys, but can also be partially metabolized by the liver. In liver disease, the liver's ability to metabolize drugs may be impaired, leading to potential toxic levels of vancomycin in the body. Erythromycin (A) can also be affected by liver disease, but it mainly requires dose adjustment in severe liver impairment. Gentamycin (B) is primarily eliminated through the kidneys and does not require dose adjustment in liver disease. Penicillin G (D) is mainly excreted through the kidneys and does not require dose adjustment in liver disease.

Correct Answer: B

Rationale: The correct choice for treating aspergillosis is B: Amphotericin B. It is the most appropriate due to its broad antifungal spectrum, including activity against Aspergillus species. Amphotericin B is often considered the first-line treatment for invasive aspergillosis. Terbinafine (A) is more commonly used for dermatophyte infections, not aspergillosis. Flucytosine (C) is mainly used for Cryptococcal infections. Itraconazole (D) may have some activity against Aspergillus, but it is generally less effective than Amphotericin B for invasive cases.

Correct Answer: C

Rationale: Correct Answer: C - Intestinal Rationale: 1. Corticosteroids suppress the immune system. 2. Intestinal tuberculosis can lead to perforation, and corticosteroids can mask symptoms and worsen the condition. 3. Miliary and meningeal TB benefit from corticosteroids to reduce inflammation. 4. Renal TB is treated with antibiotics, not corticosteroids. Summary: - A: Corticosteroids are not contraindicated in miliary TB. - B: Corticosteroids are beneficial in meningeal TB. - C: Corticosteroids can worsen intestinal TB. - D: Renal TB is treated with antibiotics, not corticosteroids.

Correct Answer: C

Rationale: The correct answer is C: Valacyclovir. Valacyclovir is an antiviral medication commonly used to treat herpes simplex virus infections. It is a prodrug of acyclovir, which inhibits viral replication by targeting the viral DNA polymerase enzyme. Valacyclovir is effective in reducing the severity and duration of genital herpes outbreaks. A: Zanamivir is an antiviral medication used to treat and prevent influenza virus infections, not herpes simplex virus infections. B: Lamivudine is an antiretroviral medication used to treat HIV and hepatitis B infections, not herpes simplex virus infections. D: Cidofovir is an antiviral medication used to treat cytomegalovirus (CMV) infections, not herpes simplex virus infections. In summary, Valacyclovir is the most appropriate choice for treating genital herpes simplex virus infection due to its effectiveness in inhibiting viral replication and reducing the severity of outbreaks.

Correct Answer: A

Rationale: The correct answer is A: Nalidixic acid + Nitrofurantoin. This combination does not exhibit supraadditive synergism because both drugs have similar mechanisms of action targeting bacterial DNA synthesis. In contrast, the other choices involve drug combinations with different mechanisms of action which result in synergistic effects, making them more effective against a wider range of microbes. Amoxicillin + Clavulanic acid work together to inhibit bacterial cell wall synthesis, Pyrimethamine + Sulfadoxine target folate biosynthesis pathways, and Sulfamethoxazole + Trimethoprim inhibit sequential steps in bacterial folic acid synthesis. Therefore, A is the correct answer as the combination lacks synergy due to overlapping mechanisms of action.