CHAPTER 20: Infectious Diseases

INTRODUCTION: KEY POINTS

• Infections are an important cause of morbidity and mortality in kidney transplant recipients.

Prior to Transplantation

• Identify potential infectious issues in both donors and recipients.

• Identify and evaluate both donors and recipients for past, present, and potential infections.

• Confirm that recipients are properly vaccinated.

Posttransplantation

• Some early recipient infections may be donor-derived.

• Recognizing the time course of infections provides useful information and should be carefully considered.

• Prophylaxis and treatment of acute rejection may alter or shift the timeline of infections.

• The severity of immunocompromise should always be evaluated based on:

  • Time from transplant

  • Type/dose of immunosuppression

  • Presence of recent rejection

  • Use of T-cell–inhibiting agents

DIAGNOSTIC POINTS

• Transplant recipients may present with altered inflammatory responses to infection.

• Common infections may present in uncommon ways.

• Clinicians must approach transplant patients with a high degree of suspicion for infection and consider that infection may be present until proven otherwise.

• Concurrent infections (more than one single pathogen) are more likely in transplant patients than in the general population.

• The differential diagnosis of potential pathogens is more extensive in transplant patients than in nonimmunocompromised individuals.

• Have a low threshold for both enhanced imaging studies and biopsies. Imaging studies and biopsies should be obtained early in order to make a prompt definitive diagnosis and establish an adequate therapeutic approach—if in doubt, image and biopsy.

• It may be difficult to distinguish between colonization and active infection.

IMMUNOLOGIC DEFICIT: T-CELL INHIBITION LEADS TO INCREASED RISK OF OPPORTUNISTIC INFECTIONS

• Immunosuppression, although necessary to protect the transplanted kidney from rejection, increases the risk of infections.

• Most immunosuppressive agents are associated with T-cell depletion, reduced T-cell activation, or inhibition of T-cell proliferation.

• The net result of immunosuppression is reduced cell-mediated immunity.

• Immunosuppression levels are the greatest from month 1 to 6 posttransplant, as well as during any subsequent episodes of rejection that require intensified immunosuppression.

• Measurement of CD4+ T-helper cells is not as predictive of opportunistic infections in transplant recipients as it is in patients with HIV/AIDS.

CLINICAL PREDICTORS OF POSTTRANSPLANT INFECTIONS

• Structural abnormalities

  • Ureteral strictures

  • Fluid collections

  • Foreign bodies

• Environmental exposures

  • Heavy burden of exposure to opportunistic pathogens

  • Live vaccines

• Degree of immunosuppression

DONOR/RECIPIENT SCREENING

• Human immunodeficiency virus

• Hepatitis A

• Hepatitis B

• Hepatitis C

  • Testing for bloodborne viruses (HIV, hepatitis B, hepatitis C) should be performed on the recipient and the donor no more than 2 weeks prior to transplant (and by nucleic acid testing (polymerase chain reaction [PCR]) to avoid potential transfer of infection from a donor recently exposed and in the “window period”

• Herpes Simplex Virus (HSV)

• Cytomegalovirus (CMV)

• Epstein-Barr virus (EBV)

• Toxoplasma

• Human T-lymphotropic virus (HTLV-1) (controversial)

• Strongyloides serology or stool assay (in recipients from endemic regions)

• Latent ...