**Question:** Drug of choice for syphilis during pregnancy is

A. Penicillin
B. Chloroquine
C. Acyclovir
D. Fluconazole

**Core Concept:** Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. Treatment options depend on the stage of the disease, with penicillin being the first-line treatment for early syphilis, including syphilis during pregnancy.

**Why the Correct Answer is Right:** Penicillin is the treatment of choice for syphilis due to its high efficacy, low toxicity, and minimal risk to the fetus. It is effective against both treponemes and beta-lactamase-producing organisms. Penicillin is classified as the first-line treatment for early syphilis, including pregnancy, as it is safe for both the mother and the fetus.

**Why Each Wrong Option is Incorrect:**

B. Chloroquine: While chloroquine is used for treating malaria, it is not effective against T. pallidum and should not be considered as an option for syphilis treatment.

C. Acyclovir: Acyclovir is an antiviral medication used for treating herpes virus infections, not syphilis, which is caused by bacteria.

D. Fluconazole: Fluconazole is an antifungal medication used for treating fungal infections, not bacterial infections like syphilis caused by T. pallidum.

**Why Correct Answer is Right:** Penicillin is safe during pregnancy due to its minimal risk to the fetus. In addition to its efficacy against T. pallidum, penicillin's minimal risk is crucial when treating pregnant patients to prevent vertical transmission, which is the transmission of syphilis from the mother to the fetus during pregnancy or childbirth. The World Health Organization (WHO) recommends benzathine penicillin G as the first-line treatment for syphilis during pregnancy to prevent complications like congenital syphilis, which can cause severe neurological, cardiovascular, and ophthalmological abnormalities in the child.

**Clinical Pearl:** Penicillin is considered safe during pregnancy because it does not cross the placenta, making it an ideal antibiotic choice for treating syphilis in pregnant women.

**Why Each Wrong Answer is Incorrect:**

A. Chloramphenicol: Chloramphenicol is an antibiotic that crosses the placenta, increasing the risk of congenital malformations and toxicity in the fetus.

B. Co-trimoxazole: Co-trimoxazole is an antibiotic combination that crosses the placenta and may cause toxicity in the fetus.

C. Erythromycin: Erythromycin is an antibiotic that crosses the placenta and can lead to fetal toxicity.

D. Ceftriaxone: Ceftriaxone is a broad-spectrum antibiotic that crosses the placenta and can cause toxicity in the fetus.

**Clinical Pearls:** The choice of a drug