Aciclovir resistance among Indian strains of Herpes simplex virus as determined using a dye uptake assay

Resistance to aciclovir (ACV) among Herpes simplex virus (HSV) isolates is increasingly being reported in the literature particularly in immunocompromised patients. However, there is only limited data available from India despite widespread use of ACV in our hospital. A cross-sectional study was hence conducted to determine the aciclovir (ACV) susceptibility of HSV 1 and 2 isolates using a dye uptake (DU) assay. This study showed a 3.0% prevalence of ACV resistance among HSV-1 strains (2/66, median IC 50 0.098 microg/mL) while in HSV-2 strains, it was 7.8% (5/64, median IC 50 0.195 microg/mL). The IC 50 for the HSV-1 and HSV-2 strains resistant to ACV was greater than or equal to 6.25 microg/mL.