BK polyomavirus-associated hemorrhagic cystitis among pediatric allogeneic bone marrow transplant recipients: Treatment response and evidence for nosocomial transmission

Background: BK polyomavirus-associated hemorrhagic cystitis (BK-PyVHC) is a significant complication of allogenic hematopoietic stem cell transplantation (HSCT), but risk factors and treatment are currently unresolved. BK-PyVHC typically presents with clinical cystitis, macrohematuria, and increasing urine and blood BKV loads. Objectives: Characterization of children undergoing allogeneic HSCT with BK-PyVHC and their clinical and antibody response to cidofovir treatment. Study design: By prospective screening of urine and plasma in 50 pediatric allogenic HSCT performed between 2008 and 2010, we identified 6 (12%) children with BK-PyVHC. Cidofovir was administered intravenously to 5 patients and intravesically to 4 patients (3 double treatments). Results: Decreasing BKV viremia of >2 log(10) copies/mL and clinical resolution was seen in 4 patients over 5-12 weeks. Responses occurred only in patients mounting BKV-specific IgM and IgG responses. Epidemic curve plots, BKV genotyping and contact tracing provided evidence of transmission between 2 BKV-seronegative patients, but ruled out transmission among the remaining four patients Conclusions: The data suggest that BK-PyVHC may be the result of nosocomial transmission in children with low/undetectable BKV antibodies and raises urgent questions about appropriate infection control measures and the role of cidofovir. (C) 2012 Elsevier B.V. All rights reserved.