A 24-year-old woman is found to have a painless indurated genital ulcer. Serology shows RPR reactive 1:8, TPPA positive, IgM anti-Treponema positive. HIV test is negative. She is 10 weeks pregnant. What is the preferred treatment for primary syphilis in pregnancy?
- A Doxycycline 100 mg twice daily for 14 days
- B Benzathine penicillin G 2.4 MU IM single dose ✓
- C Azithromycin 2 g single oral dose
- D Ceftriaxone 1 g IM daily for 10 days
Explanation
Benzathine penicillin G 2.4 MU IM single dose remains the treatment of choice for primary, secondary, and early latent syphilis in all patients including pregnant women. Penicillin is the ONLY antibiotic proven to prevent congenital syphilis by crossing the placenta. Doxycycline and tetracyclines are contraindicated in pregnancy. Azithromycin is NOT recommended due to emerging macrolide resistance in T. pallidum (A2058G/A2059G 23S rRNA mutations). Ceftriaxone is an alternative only in penicillin allergy (with careful monitoring), but penicillin-allergic pregnant women should undergo penicillin desensitisation and be treated with penicillin.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.