The role of cytomegalovirus infection and disease in pediatric bone marrow transplant recipients in Mexico City in the context of viral drug resistance

We aimed to identify those pediatric patients undergoing ABMT with CMV EOD who developed GCV resistance. Forty-seven patients were analyzed following ABMT. Prospective post-transplant CMV monitoring was performed weekly for the detection of viral leukocyte DNAaemia, viral plasma DNAaemia, and viral DNAuria by PCR. Plasma DNAaemia was confirmed from whole blood by the detection of CMV pp67 late mRNA using NASBA technology. In the cases of persistence of viral DNA in plasma, and positive viral RNA detection in blood, CMV drug resistance screening by comprehensive PCR-based RFLP and sequencing of the viral UL97 gene were performed retrospectively. Thirty of the 47 (63.82%) patients showed active CMV infection with 27/30 (74.4%) patients belonging to the D+R+ group and 25/30 with proven viral replication. In total, 2/30 (6.6%) children developed CMV pneumonia proven by immunohistochemistry. Screening of the viral UL97 gene revealed in one of these two cases (1/30, 3.3%) the simultaneous presence of two point mutations in codon 460 (M460V, M460I) conferring GCV resistance. The CMV seroprevalence (81%) and the incidence of active infection (63.8%) in Mexican children undergoing ABMT are very high.