Microbiology

The pathogens requiring consideration in the early postengraftment period are summarized in Table 99.4. Bacterial infections arising from indwelling intravas-cular devices and mucositis in the setting of GVHD continue to occur in the early postengraftment period. The microbiology of these infections is similar to that encountered in the preengraftment period. Invasive fungal infections due to resistant yeasts, Aspergillus species, Fusaria species, and zygomycetes also occur during this period. GVHD, graft failure, and corticos-teroid therapy are major risk factors for invasive aspergillosis, whose peak incidence in allogeneic HSCT recipients occurs at this time.27 Patients remain at-risk for CRV infections. Unlike children, in whom aden-ovirus infection is more often seen in the preengraft-ment period, adult patients tend to develop aden-ovirus infection beyond 90 days.42 As in children, pneumonia, hemorrhagic cystitis, hemorrhagic colitis, and nephritis are the major clinical syndromes.

Table 99.4 Pathogens encountered in the early postengraftment period

Pathogens Common sites of involvement, origin

Common Bacteria

Staphylococci Streptococci Enterococci Gram-negative bacilli

Viruses

CMV Viremia, pneumonia, enterocolitis; reac tivation of latent infection, primary infection

Fungi

Aspergillus species Pneumonia, CNS Less Common

Bacteria

Legionella species Pneumonia, exclude nosocomial water source

Listeria Meningoencephalitis, bacteremia monocytogenes

Viruses

Adenovirus

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