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Six cases of cytomegalovirus retinitis (CMVR) after allogeneic hematopoietic stem cell transplantation were diagnosed between 2002 and 2005 in our center, whereas only one case was diagnosed between 1985 and 2001. Cumulative incidence reaches 2.2%, whereas this complication has been rarely described after hematopoietic stem cell transplantation. We aimed to describe clinical and biologic features of CMVR and search for risk factors associated with CMVR. CMVR was diagnosed on specific funduscopic examination in all patients either on visual symptoms (n=3) or on systematic ophthalmologic examination (n=3). CMVR occurred in the context of unrelated transplantation in patients with profound immune defect and multiple episodes of cytomegalovirus (CMV) reactivation. The combination of a CMV-seropositive recipient and CMV-seronegative donor was the leading risk factor.

The emergence of a resistant strain is a theoretical threat after extensive use of antiviral drugs. We report the emergence of a ganciclovir-resistant cytomegalovirus (CMV) strain in a kidney transplant recipient during oral ganciclovir maintenance treatment. The patient was treated by oral ganciclovir for 2 months after successful treatment of CMV primary infection by intravenous ganciclovir. He developed a new episode of CMV infection with no clinical response to intravenous ganciclovir. The CMV isolate exhibited both phenotypic and genotypic resistance to ganciclovir. The CMV isolate was constituted of a mixture of strains, with and without a mutation at codon 460 of the UL97 gene. The clinical condition improved when mycophenolate mofetil (MMF) was discontinued, and a short course of intravenous globulin was added to ganciclovir. The emergence of the CMV strain could be secondary to more potent immunosuppression provide by MMF or subtherapeutic level obtained during oral ganciclovir treatment. We believe that ganciclovir resistance must be part of the differential diagnosis when a patient relapses or fails to respond to ganciclovir treatment.

We report the case of a lung transplant recipient with progressive cytomegalovirus (CMV) disease due to a resistant CMV strain emerging under ganciclovir (GCV) therapy. A discriminative polymerase chain reaction (PCR) assay, designed to detect the resistance-related V460 mutation within the viral enzyme UL97, revealed the presence of a mutated strain in a heterogeneous isolate 51 days after transplantation. The conventional antiviral susceptibility assay had failed to demonstrate resistance to GCV. Under prolonged GCV therapy, the mutated strain dominated the wild-type strain, as shown by the PCR assay. This domination led to laboratory resistance, associated with recurrent fever and progressively 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.

Cytomegalovirus (CMV) viremia was systematically studied in 56 patients having undergone bone marrow transplantation for leukemia or aplastic anemia. Of the patients who survived at least three months, 57% had CMV viremia with a frequency peak between the 7th and the 9th weeks. We describe possible clinical signs associated with viremia, particularly late peripheral and/or central thrombocytopenia. The occurrence of viremia was studied according to the specific preexisting immune status of recipients and donors; granulocyte transfusions and graft-versus-host disease. The relationship between these parameters and viremia provides a basis for the analysis of prophylactic treatments of CMV infection.