Acyclovir-resistant corneal HSV-1 isolates from patients with herpetic keratitis

The prevalence and molecular characteristics of isolates from 173 immunocompetent patients with herpetic keratitis (HK) whowere infected with acyclovir (ACV)-resistant(ACVR) corneal herpes simplex virus (HSV)-1 was determined. Isolates from 11 (6.4%) of the patients were ACVR, and 9 of these 11 patients were refractory to therapy with ACV; the ACVRisolates from 5 and 1 of these 9 patients were cross-resistant to gancyclovir and to both gancyclovir and foscarnet, respectively. Of the 11 ACVRisolates, 10 had, in the thymidine kinase gene, mutations that presumably conferred the ACVRphenotype. These data demonstrate a relatively high prevalence of corneal HSV-1 ACVRisolates in patients with HK, which emphasizes the need to monitor for ACV susceptibility in patients with HK who are refractory to therapy with ACV.