A 23 year old pregnant woman has UTI and presents to the ER with fever, frequency and urgency. Which of the following antibiotics can cause potential harm to her fetus?

Correct Answer: C

Rationale: The correct answer is C: Gentamycin. Gentamycin is known to have potential harmful effects on the fetus, such as causing hearing loss and kidney damage. This is due to its ability to cross the placental barrier. Amoxicillin (B) and Cephalexin (D) are both considered safe for use in pregnancy and are commonly prescribed for UTIs. Nitrofurantoin (A) is typically avoided in the third trimester due to the risk of hemolytic anemia in the newborn, but it is considered safe earlier in pregnancy. Therefore, Gentamycin is the correct choice as it poses a higher risk to the fetus compared to the other antibiotics.

Correct Answer: B

Rationale: Step 1: Terbinafine is a fungicidal drug that inhibits fungal squalene epoxidase enzyme, disrupting fungal cell membrane synthesis. Step 2: Onychomycosis of toenails is a common fungal infection that terbinafine is specifically effective against. Step 3: The patient being a 56-year-old woman with diabetes may require a drug with good efficacy and safety profile, making terbinafine an appropriate choice. Step 4: Griseofulvin (A) works by disrupting microtubule function, not inhibiting squalene epoxidase. Itraconazole (C) is an azole antifungal that inhibits ergosterol synthesis, not squalene epoxidase. Amphotericin B (D) is a polyene antifungal used for systemic mycoses, not onychomycosis.

Correct Answer: A

Rationale: Diethylcarbamazine is the correct answer for treating filariasis because it targets the microfilariae, adult worms, and larvae of filarial parasites. It is specifically designed to kill these parasites and is considered the drug of choice for filariasis treatment. Albendazole, Levamisole, and Piperazine are not effective against filarial parasites and are used for different types of infections or conditions. Albendazole is mainly used for treating intestinal worms, Levamisole is used for parasitic infections in animals, and Piperazine is used for treating pinworm infections. Thus, only Diethylcarbamazine directly targets and eliminates filarial parasites, making it the correct choice for filariasis treatment.

Correct Answer: D

Rationale: Rationale: 1. Ritonavir is a protease inhibitor used in HIV treatment. 2. It works by inhibiting the HIV protease enzyme, preventing viral replication. 3. Lamivudine, Efavirenz, and Stavudine are not protease inhibitors but work through different mechanisms. 4. Lamivudine is a nucleoside reverse transcriptase inhibitor, Efavirenz is a non-nucleoside reverse transcriptase inhibitor, and Stavudine is another nucleoside reverse transcriptase inhibitor. Summary: Ritonavir is the correct answer as it directly targets the HIV protease enzyme, unlike the other options which act on reverse transcriptase enzymes.

Correct Answer: B

Rationale: The correct answer is B: Azithromycin. It is preferred for short-term treatment due to its long half-life allowing once-daily dosing. Azithromycin has a broad spectrum of activity against many pathogens causing ENT, respiratory, and genital infections. It is well-tolerated and has fewer drug interactions. Other choices like A: Erythromycin have a higher frequency of dosing and more side effects. C: Clarithromycin and D: Roxithromycin are not typically given once daily for 3 days.