Chapter 126. Infections in Transplant Recipients (Part 2) potx

Chapter 126. Infections in
Transplant Recipients
(Part 2)

In many transplantation centers, transmission of infections that may be
latent or clinically inapparent in the donor organ has resulted in the development
of specific donor-screening protocols. In addition to ordering serologic studies
focused on viruses such as herpes-group viruses [herpes simplex virus types 1 and
2 (HSV-1, HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), human
herpesvirus (HHV) type 6, Epstein-Barr virus (EBV), and Kaposi's sarcoma–
associated herpesvirus (KSHV)] as well as hepatitis B and C viruses, human
immunodeficiency virus (HIV), human T cell lymphotropic virus type I, and West
Nile virus, donors should be screened for parasites such as Toxoplasma gondii and
Trypanosoma cruzi (the latter particularly in Latin America). Clinicians caring for
prospective organ donors should also consider assessing stool for parasites, should
examine chest radiographs for evidence of granulomatous disease, and should
perform purified protein derivative (PPD) skin testing or obtain blood for immune
cell–based assays that detect active or latent Mycobacterium tuberculosis
infection. An investigation of the donor's dietary habits (e.g., consumption of raw
meat or fish or of unpasteurized dairy products), occupations or avocations (e.g.,
gardening or spelunking), and travel history (e.g., travel to areas with endemic
fungi) is also mandatory. It is expected that the recipient will have been likewise
assessed. Because of immune dysfunction resulting from chemotherapy or
underlying chronic disease, however, direct testing of the recipient may prove less
reliable. This chapter considers aspects of infection unique to various
transplantation settings.
Infections in Hematopoietic Stem Cell Transplant (HSCT) Recipients
Transplantation of hematopoietic stem cells from bone marrow or from
peripheral or cord blood for cancer, immunodeficiency, or autoimmune disease
results in a transient state of complete immunologic incompetence. Immediately
after transplantation, both phagocytes and adaptive immune cells (T and B cells)

are absent, and the host is extremely susceptible to infection. The reconstitution
that follows transplantation has been likened to maturation of the immune system
in neonates. The analogy does not entirely predict infections seen in HSCT
recipients, however, because the new cells mature in an old host who has several
latent infections already. Nevertheless, most infections occur in a predictable time
frame after transplantation (Table 126-2).
Table 126-
2 Common Sources of Infections after Hematopoietic Stem
Cell Transplantation

Period after Transplantation
Infection Site Early
(<1 Month)
Middle (1–
4
Months)
Late (>6
Months)
Disseminated Aerobic
gram-negative,
gram-positive
bacteria
Nocardia
Candida,
Aspergillus

Encapsulated
bacteria
(Streptococcus
pneumoniae

,
Haemophilus
influenzae,
Neisseria
meningitidis)
Skin and
mucous membranes
HSV HHV-6 VZV
Lungs Candida
,
Aspergillus

HSV
CMV,
seasonal respiratory
viruses
Pneumocystis

Toxoplasma

Pneumocystis

Gastrointestinal
tract
CMV
Kidney
BK virus,
adenovirus
BK virus
Brain HHV-6 Toxoplasma

Toxoplasma
JC virus
Bone marrow HHV-6

Note: CMV, cytomegalovirus; HHV-
6, human herpesvirus type 6; HSV,
herpes simplex virus; VZV, varicella-zoster virus.