FAILURE OF GANCICLOVIR TREATMENT ASSOCIATED WITH SELECTION OF A GANCICLOVIR-RESISTANT CYTOMEGALOVIRUS STRAIN IN A LUNG-TRANSPLANT RECIPIENT

We report the case of a lung transplant recipient with progressive cyt omegalovirus (CMV) disease due to a resistant CMV strain emerging unde r ganciclovir (GCV) therapy. A discriminative polymerase chain reactio n (PCR) assay, designed to detect the resistance-related V460 mutation within the viral enzyme UL97, revealed the presence of a mutated stra in in a heterogeneous isolate 51 days after transplantation. The conve ntional antiviral susceptibility assay had failed to demonstrate resis tance to GCV. Under prolonged GCV therapy, the mutated strain dominate d the wild-type strain, as shown by the PCR assay. This domination led to laboratory resistance, associated with recurrent fever and progres sively severe retinitis. As this discriminative PCR assay was shown to be effective in detecting mutated strains that constitute a minority in the virus load, it should allow better management of patients with CMV disease.