[Acyclovir-resistant herpes simplex virus infections in immunocompromised patients].

In order to determine the sensitivity of herpes simplex virus (HSV) isolates from immunocompromised patients treated with antiviral compounds, a retrospective study was carried out in the Clinical Virology Department of the University Medical Centre, Amsterdam. Virus isolates from four AIDS patients and one bone marrow transplant recipient were examined for their sensitivity for the antiviral compounds used by means of plaque reduction assay. In some of the virus isolates, from patients in whom resistance was assumed on clinical grounds, in vitro resistance of the HSV to acyclovir (ACV) could be demonstrated, both after oral and after parenteral administration. There was a clear correlation between the clinical course of the HSV infection and in vitro resistance. ACV resistant virus isolates were sensitive to foscarnet, both clinically and in vitro. In immunocompromised patients treated for some time with ACV for HSV infection, resistance should be considered at lack of results or progression of the lesion and when necessary be demonstrated in vitro. Alternative therapy then consists of intravenous foscarnet treatment.