Introduction

Hematopoietic stem cell transplantation (HSCT) has been increasingly used in the treatment of malignant and nonmalignant hematologic disorders, autoimmune diseases, and genetic and metabolic diseases. More than 50,000 HSCTs are performed annually worldwide.1 Despite significant advances in defining optimal immunosuppressive regimens, in shortening the duration of neutropenia through the availability of hematopoietic growth factors, and in preventing and managing infectious and noninfectious complications, HSCTs continue to be associated with significant morbidity and mortality. Infectious and noninfectious complications such as graft-versus-host-disease (GVHD), adult respiratory distress syndrome (ARDS), and venoocclusive disease (VOD) are the major contributors to adverse outcome.

This chapter focuses on the recognition, management, and prevention of infectious complications following autologous and allogeneic HSCT. Guidelines focusing on infection prevention were recently published by the Centers for Disease Control and Prevention,2 and include general and infection-specific strategies, as well as recommendations regarding infection control. The latter is beyond the scope of this discussion and the reader is referred to the guidelines as well as to a recent excellent review regarding infection control management in HSCT.3

A thorough pretransplant infectious disease evaluation is essential in HSCT candidates. Specific infectious complications following HSCT are predictable and can be anticipated based upon the sequential suppression of the various components of host defense associated with the conditioning regimen and subsequent HSCT.4 The clinical syndromes that most commonly occur and the pathogens involved vary over time. For purposes of differential diagnosis in the HSCT recipient with suspected infection, three distinct periods of infection risk exist, each with unique deficiencies in host immune function.5 These include the preengraft-ment period (from the initiation of the conditioning regimen to engraftment), the early engraftment period (from engraftment to day 100), and the late engraft-ment period in allogeneic HSCT recipients (from day 100 until cessation of immunosuppressive medications). This chapter reviews the appropriate pretrans-plant infectious disease evaluation; the immune defects and associated infectious complications during the preengraftment, early engraftment, and late engraft-ment periods; and the prevention, diagnosis, and management of selected syndromes and pathogens encountered in HSCT recipients.

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