A 30-year-old woman has VDRL 1:4 reactive, TPHA positive, FTA-ABS positive. She has no history of syphilis treatment. She is 12 weeks pregnant. What is the recommended treatment?
- A Doxycycline 100 mg BD for 14 days (standard alternative for penicillin allergy)
- B Benzathine penicillin G 2.4 million units IM single dose; penicillin allergy should be assessed; if truly allergic, desensitisation and benzathine penicillin G is still the treatment of choice in pregnancy as no alternative adequately prevents congenital syphilis ✓
- C Azithromycin 2 g single dose; safe in pregnancy and equivalent to penicillin for syphilis
- D Erythromycin 500 mg QID for 14 days is the preferred alternative in pregnancy as it crosses the placenta well
Explanation
In pregnancy, benzathine penicillin G (BPG) 2.4 million units IM is the ONLY proven treatment for syphilis in pregnancy that crosses the placenta and effectively treats the fetus, preventing congenital syphilis. Stage determines dosing: primary, secondary, early latent — 2.4 MU IM single dose; late latent or unknown duration — 2.4 MU IM weekly × 3 doses. For women who are truly penicillin-allergic, WHO/CDC guidelines recommend penicillin desensitisation followed by BPG treatment. Doxycycline is contraindicated in pregnancy (fetal dental/bone toxicity). Erythromycin does NOT adequately penetrate the placenta to treat fetal syphilis. Azithromycin has emerging macrolide resistance in T. pallidum and is NOT recommended.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.