skip to main content

Topical Cidofovir for Resistant HSV — SCE Infectious Diseases MCQ

Instant feedback + full explanation. One question, done properly.

HardHIV MedicineTopical Cidofovir for Resistant HSVSCE Infectious Diseases

A 25-year-old man with HIV (CD4 50) presents with extensive perianal and genital ulceration unresponsive to 10 days of oral Aciclovir. Viral culture confirms HSV-2. Phenotypic testing shows the isolate is Aciclovir-resistant (thymidine kinase deficient). He cannot tolerate IV therapy. What topical option may be considered?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Topical Cidofovir 1% gel applied to ulcers daily

For localised Aciclovir-resistant mucocutaneous HSV, topical Cidofovir 1% gel is an established treatment option (compounded by specialist pharmacies). Cidofovir is a nucleotide analogue that does not require thymidine kinase activation and is therefore active against TK-deficient HSV mutants. It is applied once daily to affected areas. IV Foscarnet remains the systemic treatment of choice for Aciclovir-resistant HSV. Topical Aciclovir would be ineffective given resistance. Imiquimod has been used anecdotally for refractory HSV but evidence is limited.

Reference: BHIVA 2022 – OI guidelines; BASHH 2014 – Genital herpes