Demonstration of Resistant or Wild-Type Virus in Recurrent Viremia After Ganciclovir-Resistant Cytomegaloviral Infection.

Background: Ganciclovir-resistant cytomegalovirus (GR-CMV) is a serious complication of transplantation. Recurrence after primary infection is common. Little is known about CMV drug resistance and latency.
Objective: Review CMV genotype during episodes of recurrent CMV viremia after prior documentation of ganciclovir resistance to evaluate if resistance is redemonstrated.
Methods: All adult transplant recipients with history of GR-CMV viremia from January 1, 2011, to December 31, 2015, were screened; those with subsequent laboratory evidence of recurrent CMV viremia and genotyping were included.
Results: A total of 23 patients had genetically confirmed GR-CMV within the study time period; 14 were excluded due to lack of repeat resistance testing at recurrence and 4 due to of lack of negativity between testing, leaving 5 patients with 7 episodes of recurrent viremia to evaluate. At first recurrent viremia, 4 patients (80%) demonstrated resistant genotype; 1 patient had wild type. Two patients went on to have a second viremia recurrence; both demonstrated wild-type genotype, despite the fact that the first recurrence in these patients was resistant genotype.
Conclusion: In transplant recipients with history of GR-CMV, it appears that there is strain variability in latency: repeat genetic testing in patients with recurrent viremia after GR-CMV should be conducted. In the setting of wild-type repopulation, use of GCV should be considered.