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Syphilis Pregnancy Penicillin Desensitisation — SCE Infectious Diseases MCQ

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HardSTIsSyphilis Pregnancy Penicillin DesensitisationSCE Infectious Diseases

A 28-year-old woman presents with a painless vulval ulcer and bilateral non-tender inguinal lymphadenopathy. She reports a new sexual partner 4 weeks ago. Point-of-care treponemal test is positive. RPR is 1:64. She is 8 weeks pregnant and has documented penicillin anaphylaxis. What is the management?

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Correct answer: D — Penicillin desensitisation followed by Benzathine Penicillin G 2.4 MU IM — penicillin is the ONLY drug proven to prevent congenital syphilis; desensitisation is mandatory in pregnancy with penicillin allergy

In pregnancy, Benzathine Penicillin G is the ONLY antibiotic proven to treat the mother AND prevent congenital syphilis. Doxycycline is teratogenic. Azithromycin resistance is increasing and transplacental transfer is unreliable. Erythromycin does not achieve adequate fetal concentrations. For pregnant women with documented penicillin anaphylaxis, DESENSITISATION in a monitored setting (ICU/HDU) followed by standard Benzathine Penicillin G treatment is mandated by all major guidelines. This is non-negotiable — the stakes of congenital syphilis are too high for alternative agents.

Reference: BASHH 2019 – Syphilis in pregnancy; CDC 2021; BHIVA 2025 – Pregnancy