Complications
of immunosuppression
All immunosuppressive regimens used in organ transplantation increase
the risk of infection and malignancy.
Infection
Transplant recipients receiving immunosuppressive therapy are at high
risk from opportunistic infection, especially by
Bacterial
infection
The risk of bacterial infection is highest during the first month after
transplantation. Transplant recipients are, like all patients undergoing major
surgery, at risk of bacterial infections in the wound, respiratory tract and
urinary tract. It is standard practice to give a broad-spectrum antibiotic to
cover the perioperative period as prophylaxis against wound infection and
possible bacterial contamination of the donor organ. The risk of bacterial
infection is greatest in transplant recipients who are critically ill before or
after surgery and are in the intensive care unit with indwelling catheters and
lines. After recovery from surgery, the risk of bacterial infection is much
reduced. Tuberculosis is a concern in patients who have previously had
rnycobacterial infection and in patients from the Indian subcontinent, and it is
usual to give immunochemoprophylaxis to these individuals for a period of
6—12 months after transplantation.
Viral
infection
The risk of viral infection is highest during the first 6 months after
transplantation and the most common problem is CMV infection. Most adults (>
80 per cent) develop CMV infection when they are children and have acquired
immunity, as evidenced by the presence of IgG antibodies to CMV Following organ
transplantation, CMV disease may arise because of reactivation of latent
infection or because of primary infection that can be transmitted by an organ
from a CMV-positive donor. The recipients at most risk from CMV infection are
those who are CMV seronegative and receive an organ from a CMV-seropositive
donor. Matching seronegative donors with seronegative recipients is an effective
strategy for reducing the risk of CMV infection but is not very practicable. CMV
disease typically presents with a high swinging fever, lethargy and leucopenia.
The severity of the disease is variable and the clinical picture depends on the
organ system most affected. It may present as:
• pneumonia;
• gastrointestinal disease;
• hepatitis;
• retinitis;
•encephalitis.
Herpes
simplex virus (HSV) infection is common after transplantation and is usually due
to reactivation of latent infection. It causes rnucocutaneus lesions around the
mouth and sometimes the genitalia. These usually respond to topical treatment
with acyclovir, but in severe cases systemic antiviral therapy is needed.
Disseminated HSV infection is rare. Varicella zoster infection occurs more
frequently in transplant patients and should be treated with systemic antiviral
therapy.
Protozoal
infection
Pneumocystis
carinii is the most important
protozoal infection after transplantation. It occurs during the first few
months and presents with respiratory symptoms. The diagnosis is made by
examination of bronchoalveolar lavage fluid or lung biopsy material for evidence
of parasite infection. Prophylaxis with co-trimoxazole is highly effective and
is usually continued for 6 months after transplantation.
Fun
gal infection
Invasive fungal infections are uncommon in renal transplant recipients
but infection with Candida or Aspergillus is more common after
other types of solid organ transplantation. Fungal infection usually occurs in
the first 3 months after transplantation, and early diagnosis and aggressive
treatment are essential to avoid fatal infection.
Malignancy
After transplantation there is an increased risk of developing certain
types of malignant disease, especially those turnouts where viral infection
plays an aetiological role. The increased risk of malignancy is particularly
high for skin cancer and non-Hodgkin’s lymphoma. Most of the skin cancers seen
are squamous cell carcinomas, but basal cell carcinoma and malignant melanoma
are also more common (Fig. 11.11). The risk of skin cancer after transplantation
rises with age and with exposure to sunlight, and it has been predicted that 50
per cent of transplant patients will develop a skin malignancy by 20 years.
Patients must be warned of this risk before they undergo transplantation and
advised to use an effective sun-screen. They should undergo regular review of
their skin to detect malignancy and when such lesions occur they must be treated
promptly and aggressively.
The
risk of developing non-Hodgkin’s lymphoma is significantly increased after
transplantation. This type of malignancy is classified as post-transplant
lymphoproliferative disease (PTLD). Most of them are Epstein—Barr
virus-induced B-cell turnouts. The overall risk of PILD is around 1 per cent per
Transplant
patients also have a 300-fold increased risk of developing Kaposi’s sarcoma,
although this malignancy is still very uncommon after transplantation.