Treatment of acyclovir-resistant herpetic ulceration with topical foscarnet and antiviral sensitivity analysis.

Background: Herpes simplex virus (HSV) can produce persistent mucocutaneous disease in patients with the acquired immunodeficiency syndrome (AIDS). In this case report, we evaluate the efficacy, safety and viral resistance after topical foscarnet in severe genital ulceration due to acyclovir-resistant HSV-2.

Case Report: A 45-year-old African woman was known for an HIV infection with severe immunosuppression (CD4 <100/mm3). She had received a long-term prophylaxis with acyclovir (400 mg b.i.d.) for a recurrent genital herpes. Few weeks after stopping this prophylaxis, she developed large genital ulcerations progressing despite valacyclovir treatment (1,000 mg t.i.d.). Cultures were positive for HSV-2, resistance to acyclovir was shown by the plaque reduction assay and topical foscarnet was tried. Treatment consisted of a 20-min application of topical foscarnet 2.4% twice a day. Dramatic improvement was observed with rapid antalgia, and cicatrization of the genital ulcerations was observed after 50 days. HSV could not be detected on the mucosal surface. Initially, HSV-2 was resistant to acyclovir but sensitive to foscarnet. After 1 month of topical treatment, HSV-2 became sensitive to acyclovir and was still sensitive to foscarnet. Finally, after 6 weeks of treatment, no virus could be detected by culture.

Conclusion: Topical foscarnet (2.4%) is a convenient treatment for chronic genital herpes. Resistance to acyclovir disappears few weeks after stopping this drug and sensitivity to foscarnet persists during the 50 days of treatment.