Management of infectious complications of bone marrow transplantation.

Following bone marrow transplantation, patients are profoundly immunodeficient and susceptible to a variety of opportunistic infections. The types of infections vary during different intervals after transplantation. Before engraftment, neutropenia and damaged mucosal surfaces are the predominant deficits in host defenses against infection, and bacterial and fungal infections are the most common infections encountered. During the early post-engraftment period, acute graft-versus-host disease and its treatment result in a severe deficiency of cellular immunity. Cytomegalovirus infection is frequent and can result in life-threatening pneumonia. Fungal infections are also common. After the first three months, infection is much less common. However, reactivation of varicella-zoster virus (VZV) and infections with certain pathogens such as Pneumocystis carinii, can occur due to still-impaired cellular immunity.