Which of the following drugs act by inhibiting folate synthesis in bacteria and it is advisable to drink 8 ounces of water during this drug’s use because it may cause crystalluria and subsequent kidney stone formation.

Correct Answer: C

Rationale: The correct answer is C: Sulfonamides. Sulfonamides inhibit folate synthesis in bacteria by acting as competitive inhibitors of dihydropteroate synthetase. This leads to disruption of nucleic acid and protein synthesis in bacteria. Drinking 8 ounces of water during sulfonamide use helps prevent crystalluria and subsequent kidney stone formation by ensuring adequate hydration to flush out the drug and its metabolites. Vancomycin (A) acts by inhibiting cell wall synthesis, Linezolid (B) inhibits protein synthesis, and Penicillin (D) inhibits bacterial cell wall synthesis through interference with transpeptidation reactions.

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.

Correct Answer: A

Rationale: The correct answer is A: Streptomycin. Streptomycin binds to the S12 ribosomal subunit, inhibiting protein synthesis in mycobacteria. It is effective against drug-resistant tuberculosis and is used as an injectable drug. Streptomycin is known to cause ototoxicity and nephrotoxicity as side effects. Choice B: Ethambutol inhibits cell wall synthesis in mycobacteria, not protein synthesis. Choice C: Isoniazid inhibits mycolic acid synthesis in the cell wall of mycobacteria. Choice D: Rifampicin inhibits RNA synthesis by binding to the beta subunit of bacterial RNA polymerase.