Highly resistant bacteria and donor‐derived infections: treading in uncharted territory

Despite significant advances in the care of solid organ transplant recipients over the past half-century, infections remain a common cause of morbidity and mortality post transplant. Screening of donors and recipients and use of prophylactic antimicrobial agents have greatly reduced the incidence of infections following organ transplantation. Nevertheless, recent high-profile events have drawn attention to the small but real risk of transmission of donor-derived infection to organ recipients. Donor-derived disease transmissions are defined as any disease present in the organ donor that is transmitted to at least one of the recipients, which can be expected, if the donor is recognized to have the infection, or unexpected, if donor infection is unrecognized at the time of procurement (1). In many cases, transmission of latent infections, such as cytomegalovirus, hepatitis B virus, or Mycobacterium tuberculosis, and their clinical consequences are predictable in the absence of preventative measures (2–4). Intervention strategies, such as pretransplant screening, vaccination, chemoprophylaxis, or preemptive monitoring, can be employed to prevent or minimize the impact of these disease transmissions (2–4). In other cases, a pathogen may be recognized to cause acute infection in the donor prior to organ procurement. Bacteremia or other disseminated bacterial infections represent a clear risk for donor-derived infection (5–8). Even with effective treatment before organ procurement, there remains a low but inherent risk of transmission of the pathogen to the recipient. Experience has demonstrated that this risk can be mitigated by continuing treatment in the recipient post transplant, as long as the donor receives effective therapy for a short period of time prior to procurement (6, 7). For example, in the case of donors with proven bacterial meningitis, several case series and expert opinion suggest that procurement can be considered from potential donors who are treated with an active antibiotic for 24–48 h, optimally with evidence of clinical improvement in the infection (e.g., defervescence, decreased vasopressor requirement, and/or negative blood cultures), followed by active antimicrobial therapy for the recipient directed against the cultured bacterium for at least 14 days after the transplant (3, 9–11). Furthermore, all recipients of organs from these donors should be informed of the risk of potential disease transmission, consistent with current Organ Procurement and Transplantation Network (OPTN) Policy 4.2 (12). While this practice of using donors with a treated infection has expanded the pool of potential donors, it is important to note that not all infectious agents carry the same risk for transmission; donors with meningoencephalitis of unclear etiology or mycobacterial meningitis pose an unacceptable risk of disease transmission, according to most experts (3, 7, 13). Unexpected donor-derived infectious disease transmissions occur when the infection was not recognized by history, physical examination, or laboratory assessment in the donor before procurement of the organs. Especially noteworthy examples include recipient infections such as Trypanosoma cruzi, human immunodeficiency virus, hepatitis C virus, lymphocytic choriomeningitis virus, rabies, and West Nile virus (14–19). Fortunately, such unexpected transmissions are rare, likely complicating approximately 0.2% of all organ transplants (13). A more common scenario is unexpected infectious disease transmission due to preprocurement infection of the donor or contamination of the organ at the time of procurement. Bacterial infections can occur in up to 15% of donors, or organ contamination in up to 70% of procurements (5). The near universal use of peri-operative antibiotics significantly mitigates against transmission of many of these pathogens. As a result, transmission of donor-origin bacteria appears to be an infrequent event, occurring in about 1.7% of transplants in one prospective study (5). However, data reported by the US OPTN/United Network for Organ Sharing (UNOS) Disease Transmission Advisory Committee (DTAC) at the Infectious Diseases Society of America 2010 meeting clearly suggested that, when at least one case of donor-torecipient transmission of pyogenic bacteria (e.g., Pseudomonas aeruginosa, Enterobacteriaceae, vancomycin-resistant enterococci [VRE]) is recognized, transmission of bacteria to other organ recipients is