Infectious Complications of HSCT

Published on 22/03/2015 by admin

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Last modified 22/03/2015

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Chapter 132 Infectious Complications of HSCT

Andrea Velardi, Franco Locatelli

Hematopoietic stem cell transplantation (HSCT) recipients experience a transient but profound state of immune deficiency. Immediately after transplantation, patients are particularly susceptible to bacterial and fungal infections, because neutrophils are absent. Consequently, most centers start prophylactic antibiotic or antifungal treatment during the conditioning regimen. Despite these prophylactic measures, most patients will develop fever and signs of infection in the early post-transplant period. The common pathogens include enteric bacteria and fungi such as Candida and Aspergillus. An indwelling central venous line is a significant risk factor for bacterial and fungal infections with staphylococcal species and Candida being the most frequent pathogens in catheter-related infections (Chapter 172).

HSCT recipients remain at increased risk of developing severe infections even after the neutrophil count has normalized, because T-cell number and function remain below normal for months after transplantation. Unrelated donor transplant recipients are at increased risk of developing graft versus host disease (GVHD), which is an additional risk factor for fungal and viral opportunistic infections. After cord blood transplantation, infections are the consequence of the slow neutrophil engraftment and donor T-cell naïveté. In haploidentical transplantation, the increased risk of infection observed in the 1st 4-6 mo after the allograft is the consequence of T-cell depletion of the graft.

Among HSCT recipients, invasive aspergillosis, cytomegalovirus (CMV) infection and Epstein-Barr virus (EBV)–related lymphoproliferative disorders represent life-threatening complications that significantly affect patient’s outcome.

Invasive aspergillosis remains a significant cause of infectious morbidity and mortality in HSCT recipients. Despite prompt and aggressive administration of potent antifungal agents, proven cases of aspergillosis remain difficult to treat, with case fatality rates of 80-90%. The annual incidence of invasive aspergillosis has risen with use of stem cells from alternative sources. The incidence has been reported to be 7.3% in recipients of a human leukocyte antigen (HLA)-matched related donor transplant and 10.5% in patients given the allograft from either an HLA-mismatched family donor or an unrelated donor volunteer. Most cases of aspergillosis are diagnosed from 40 to 180 days after HSCT, with 30% diagnosed <40 days and 17% >6 mo after transplantation. The risk of developing aspergillosis is mainly influenced by the duration of neutropenia, GVHD occurrence, use of corticosteroid therapy, post-transplant CMV infection, viral respiratory tract infections, older age, and T-cell depletion of the graft. Patients with a previous history of invasive aspergillosis are at particular risk.

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