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Syphilis — SCE Infectious Diseases MCQ

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ModerateSTIsSyphilisSCE Infectious Diseases

A 28-year-old man presents with a painless papule on his penis that has ulcerated. He also has bilateral painless inguinal lymphadenopathy. Dark-field microscopy is unavailable. Point-of-care treponemal test is positive. RPR is 1:16. He reports the lesion appeared 2 weeks ago. He has a documented penicillin allergy (anaphylaxis with facial swelling). What is the appropriate treatment?

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Correct answer: D — Doxycycline 100 mg BD for 14 days

For early syphilis (primary, secondary, or early latent) in patients with true penicillin allergy (anaphylaxis), Doxycycline 100 mg BD for 14 days is the recommended alternative per BASHH guidelines. Ceftriaxone has potential cross-reactivity in anaphylactic penicillin allergy (though the risk is low). Azithromycin resistance in T. pallidum is increasing and single-dose Azithromycin is no longer recommended in UK guidelines. Penicillin desensitisation may be considered for neurosyphilis but is not needed for uncomplicated early syphilis when alternatives exist.

Reference: BASHH 2019 – Syphilis guidelines; WHO 2024 – STI treatment