This class of drug exert its antimicrobial action by binding to 30S ribosomes * and inhibit bacterial protein synthesis, is the drug of choice for treating non- gonoccocal urethritis caused by Chlamydia and Ureaplasma, but should be avoided in patients with liver disease:

Correct Answer: D

Rationale: The correct answer is D: Tetracyclines. Tetracyclines bind to the 30S ribosomal subunit and inhibit bacterial protein synthesis, making them effective against Chlamydia and Ureaplasma causing non-gonococcal urethritis. They should be avoided in patients with liver disease due to the potential for hepatotoxicity. A: Daptomycin is not the correct choice as it works by disrupting bacterial cell membrane function, not by binding to ribosomes. B: Carbapenems are broad-spectrum antibiotics that inhibit cell wall synthesis by binding to penicillin-binding proteins, not ribosomes. C: Cephalosporins are beta-lactam antibiotics that inhibit cell wall synthesis, not protein synthesis by binding to ribosomes. In summary, tetracyclines are the drug of choice for the given condition due to their mechanism of action on ribosomes, while the other choices are incorrect as they target different

Correct Answer: A

Rationale: The correct answer is A: Griseofulvin. Griseofulvin is the drug of choice for ringworm infections due to its effectiveness against dermatophytes. It works by inhibiting fungal cell division. Amphotericin B is used for systemic fungal infections, not ringworm. Nystatin is used for yeast infections, not ringworm. Neomycin is an antibiotic and is not effective against fungal infections like ringworm.

Correct Answer: C

Rationale: The correct answer is C: Primaquine. Primaquine is an 8-aminoquinoline antimalarial drug primarily used for the radical cure of Plasmodium vivax and Plasmodium ovale malaria, not for prophylaxis. Rationale: 1. Primaquine is not recommended for prophylactic use due to its potential for causing hemolytic anemia in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. 2. Pyrimethamine + sulfadoxine (Choice A) is a combination drug used for both treatment and prophylaxis of malaria. 3. Proguanil (Choice B) is used for prophylaxis of malaria in combination with other antimalarial drugs. 4. Mefloquine (Choice D) is used for both treatment and prophylaxis of malaria, especially in areas with chloroquine-resistant strains.

Correct Answer: B

Rationale: The correct answer is B: Ciprofloxacin. Ciprofloxacin is a fluoroquinolone antibiotic that inhibits bacterial DNA gyrase, an enzyme crucial for bacterial DNA replication and repair. By interfering with DNA function, it disrupts bacterial growth and can effectively treat most cases of uncomplicated gonorrhea. Rationale: A: Chloramphenicol inhibits protein synthesis, not DNA function. C: Streptomycin inhibits protein synthesis by binding to the bacterial ribosome. D: Erythromycin also inhibits bacterial protein synthesis and is not primarily targeted at DNA function.

Correct Answer: C

Rationale: The correct answer is C: Suramin. Suramin is the drug of choice for treating Chaga's disease caused by Trypanosoma cruzi. It is a specific drug that targets the parasite responsible for the disease. Nifurtimox is used for acute Chaga's disease, not chronic cases like in this patient. Metronidazole is not effective against Trypanosoma cruzi. Chloroquine is used for treating malaria, not Chaga's disease. Therefore, the most appropriate drug for this patient is Suramin.