Only drug used in pregnancy with syphilis ?
**Core Concept**
Prenatal syphilis treatment requires a specific antibiotic due to its teratogenic effects during pregnancy.
**Why the Correct Answer is Right**
The only drug used in pregnancy for syphilis treatment is **Pencillin G** (or its derivatives) because it effectively crosses the placenta and achieves therapeutic levels to prevent congenital syphilis. This is crucial as syphilis can cause fetal abnormalities, miscarriage, or even fetal death if left untreated. The mechanism involves the inhibition of bacterial cell wall synthesis by inhibiting the enzyme transpeptidase.
**Why Each Wrong Option is Incorrect**
**Option A:** **Ampicillin** is not the preferred choice for syphilis treatment in pregnancy due to its potential to cause kernicterus in the fetus. Although it is a broad-spectrum penicillin, its use in syphilis is not recommended.
**Option B:** **Ceftriaxone** is not the preferred option for syphilis treatment in pregnancy due to a lack of data on its efficacy and safety in this population.
**Option C:** **Erythromycin** is not effective against Treponema pallidum, the causative agent of syphilis.
**Clinical Pearl / High-Yield Fact**
It is essential to note that all pregnant women with syphilis should be treated with a single dose of **Pencillin G** (2.4 million units) intravenously, regardless of their stage of pregnancy.
**Correct Answer:** D.