Pretransplantation Evaluation: Infectious Disease

Pretransplant Screening of the Donor

Transmission of infections such as human immunodeficiency virus (HIV) or rabies from a donor organ to a recipient is rare but highlights the risk inherent with any procedure involving placement of biological material from one person into another. Although many organisms are associated with only rare transmission events, others, such as cytomegalovirus (CMV) or Epstein-Barr virus (EBV), are recognized as being unavoidable and are factored into the risk-benefit analysis of accepting an organ. Studies from the 1980s clearly established the donor as the source of CMV and EBV after transplantation, particularly to naive recipients, and have been the basis for informing a variety of preventive strategies that are discussed in the chapter on posttransplantation infections (see Chapter 78 ). Although infection with these particular agents is anticipated, a much larger repertoire of donor-derived pathogens has been identified. Examples include acute bacterial infection; viruses such as HIV, hepatitis B virus (HBV), hepatitis C virus (HCV), West Nile virus, and rabies; chronic fungi (e.g., coccidiomycosis, histoplasmosis); and parasites (e.g., Toxoplasma gondii , Strongyloides ). Accordingly, the goal of the infectious disease evaluation of the donor is to accurately assess the presence of and risk for transmission of such pathogens. Although historical or laboratory screening is not practical or even available for all potential pathogens, a careful donor history and laboratory evaluation can help to recognize the presence of risk factors or laboratory markers that can identify a donor as being more likely to transmit a pathogen. Accomplishing this allows the transplant team to minimize the risk for unintended transmission and, where appropriate, to initiate prophylactic strategies against relevant donor-derived pathogens. In addition, it provides more accurate data when the team reviews the risks for associated infections for a specific donor with a candidate and his or her family as part of the informed consent process.

Inherent limitations exist with screening deceased donors for potential pathogens, including the inability to directly ask about exposures, the confounding presence of passive antibody within the donor secondary to receipt of blood products, and the limited time available to complete the evaluation before transplantation. The ability of families to provide accurate information is limited by the fact that they are being asked about potential risks for exposure in the donor during a period of time that is likely to be accompanied by intense emotion. As important or more so, they may not know all potential exposures and risk behaviors relevant to the donor.

In the United States, federal regulation mandates specific types of testing that are performed for deceased donation. These policies are set by the Organ Procurement and Transplantation Network (OPTN). Current OPTN policy dictates screening for HIV, HBV, HCV, syphilis, EBV, and CMV along with bacterial culture of the blood and urine for donors who have been hospitalized at least 72 hours. Additional specific tests may be requested based on case-by-case criteria.

Transplantation of a segment of liver from a living donor has also occurred in the more recent era of transplantation. Since 2000, approximately 200 to 500 such procedures have been performed annually, particularly for children or small adults. Because these donors are available for physical examination and to provide their own history, infectious disease assessment can be performed in a fashion more akin to that of candidates. Potential living donors can also be educated about ways to avoid infection, minimizing the risk to their potential recipients, before organ donation. Federal regulations defining testing for living donors are currently being developed but have not been finalized yet. Recommended screening for donors is noted in Table 33-1 .

Pretransplant Evaluation of the Candidate

The infectious disease evaluation of the liver transplant candidate should help physicians (1) recognize potential pathogens with which the patient has previously been infected or colonized, (2) review antimicrobial sensitivities of potential bacterial pathogens to help guide prophylactic and treatment strategies, and (3) document the candidate’s immunological experience that influences the risk for developing infection following transplantation. Perhaps as important, the pretransplantation evaluation provides an opportunity for the candidate and family to be educated about infections associated with transplantation. Patients can be made aware of the implications of immunosuppression, including its impact not only on infectious agents contracted following the transplant procedure but also on the potential for reactivation of latent microbes already present in the patient’s body or that come from the donor. It is particularly important to inform candidates that no screening process is infallible and that an inherent risk exists for infections being present in the donor organ that could complicate the patient’s outcome despite the current screening tests used. Patients can be further educated about the availability of preventive strategies and treatment regimens for a number of potential infectious complications associated with liver transplantation, as well as strategies for safe living to minimize acquisition of infections from their environment. Finally, the infectious disease evaluation provides the opportunity to document the patient’s immunization history and to develop a plan for the delivery of appropriate vaccines before the institution of immune suppression ( Table 33-2 ).