Background: We report the case of an AIDS patient, whose persistant HSV2 ulceration was clinically and phenotypically resistant to acyclovir and foscarnet. Only five clinical isolates of simultaneous acyclovir and foscarnet resistance have been previously described.
Case report: This patient, without history of opportunistic infection, was hospitalized for a recurrent scrotal ulceration resistant to several antiviral treatment such as acyclovir, valacyclovir or foscarnet. The CD4 count was stable at 150/mm(3) and the HIV viral load was below detection level. The last recurrence appeared rapidly under valacyclovir therapy which had been introduced after 65 days of foscarnet therapy. Thus, the patient received a new dose of foscarnet. After initial efficacy, the ulceration increased once again. HSV2 phenotypic determination was done and detected, at that time, a double resistance to acyclovir and foscarnet. Healing was obtained with intravenous cidofovir.
Discussion: Foscarnet and acyclovir resistance in an HSV2 isolate is rare. This report presents several particularities. First, whereas the earlier published patients with an acyclovir and foscarnet resistant strain were widely immunocompromised, this was not the case for our patient. Secondly, in contrast with most precedent observations in which acyclovir-resistant strain disappeared after foscarnet therapy, in our case the acyclovir resistant strain remained after foscarnet therapy. Finally, few reports concerned the clinical efficacy of cidofovir in HSV infection. In this case, we proved that intravenously cidofovir was highly and rapidly effective on acyclovir and foscarnet resistant strains.