Successful foscarnet therapy for acyclovir-resistant mucocutaneous infection with herpes simplex virus in a recipient of allogeneic BMT.

A 41-year-old recipient of matched unrelated BMT acquired a severe mucocutaneous herpes simplex virus (HSV) type I infection during acyclovir prophylaxis. He was subsequently treated with high-dose acyclovir, but the HSV infection continued. In vitro analysis of the HSV isolate, obtained before and after the administration of high-dose acyclovir, demonstrated marked resistance to acyclovir but sensitivity to the antiviral agent foscarnet. The mucocutaneous HSV infection healed completely to a 16 day course of foscarnet. However, relapse of the acyclovir-resistant HSV infection occurred 202 days after the first foscarnet treatment but he responded again to a second foscarnet course. These data indicate that, with the rising frequency of acyclovir-resistant HSV infections observed in immunocompromised hosts, viral isolates should be tested for susceptibility to different antiviral drugs in recipients of BMT with recurrent or persistent HSV infections.