Efficacy of cidofovir in an HIV infected patient with an acyclovir and foscarnet resistant herpes simplex virus infection

Background. We report the case of an AIDS patient, whose persistant HSV2 ul ceration was clinically and phenotypicaly resistant to acyclovir and foscar net. Only five clinical isolates of simultaneous acyclovir and foscarnet re sistance have been previously described. Case report. This patient, without history of opportunistic infection, was hospitalized for a recurrent scrotal ulceration resistant to several antivi ral treatment such as acyclovir, valacyclovir or foscarnet. The CD4 count w as stable at 150/mm(3) and the HIV viral load was below detection level. Th e last recurrence appeared rapidly under valacyclovir therapy which had bee n 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 ti me, a double resistance to acyclovir and foscarnet. Healing was obtained wi th intravenous cidofovir. Discussion. Foscarnet and acyclovir resistance in an HSV2 isolate is rare. This report presents several particularities. First, whereas the earlier pu blished patients with an acyclovir and foscarnet resistant strain were wide ly immunocompromised, this was not the Case for our patient. Secondly, in c ontrast with most precedent observations in which acyclovir-resistant strai n 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 t hat intravenously cidofovir was highly and rapidly effective on acyclovir a nd foscarnet resistant strains.