title: Antiviral susceptibility testing of cytomegalovirus: criteria for detecting resistance to antivirals.
abstract: Testing cytomegaloviruses for antiviral susceptibility is increasing especially since the reports of 'resistance' to ganciclovir and foscarnet (Erice et al., 1989; Knox et al., 1991). There is however no standardized method for susceptibility testing nor are there criteria for designating an isolate as sensitive or resistant. In a previous paper we utilized a plaque reduction assay and suggested that a resistant strain be defined as one requiring > 12 microM ganciclovir for inhibition of 50% of viral plaques. (Drew et al., 1991) This concentration was chosen because it was at least four-fold greater than the mean concentration required to inhibit pretherapy isolates. In this paper we present the results of testing a large number of isolates prior to and during therapy with either ganciclovir or foscarnet. By analyzing the results of these assays we propose revised criteria for susceptibility of cytomegalovirus </= 5 microM for ganciclovir and <400 microM for foscarnet.
authors.affiliation: Mount Zion Medical Center of the University of California, San Francisco, San Francisco, CA 94120-7921, USA.
authors.forename: W L
authors.initials: WL
authors.lastname: Drew
authors.forename: R
authors.initials: R
authors.lastname: Miner
authors.forename: E
authors.initials: E
authors.lastname: Saleh