Kidneys From Toxoplasma-Positive Donors OK for Transplant

Compared with transplant recipients receiving kidneys from toxoplasma antibody–negative donors, those receiving kidneys from toxoplasma antibody–positive donors do not show worse outcomes, suggesting that kidneys from these donors can likely be safely used, new research showed.

“Based on our study, the largest to date exploring the outcomes of renal transplant recipients categorized by donor toxoplasma status, we can reasonably recommend that toxoplasma-positive donor transplantation is safe to perform, with close monitoring, and that such organs should not be reflexively discarded, with [some] caveats,” the authors reported in research published this month in Transplant International.

Toxoplasma, though a relatively common parasite, typically causes only mild illness in immunocompromised individuals; however, it can be reactivated and result in potentially life-threatening illness.

The key concerns of toxoplasmosis transmission involve heart transplantation, which carries the greatest risk, according to the Organ Procurement and Transplantation Network (OPTN).

“Heart transplant recipients are at highest risk for donor transmission, as the organism has a propensity to live in muscle (including cardiac muscle),” the organization cautions in its guidance. “The organism may still be transmitted in transplants of other organ types, but at a much lower rate.”

Due to the risk, the OPTN mandates that all deceased organ donors be screened for toxoplasma antibody; however, the organization recommends that the final decision on organ acceptance should be left to individual transplant centers.

With data lacking on how often those organs are indeed utilized and how the outcomes compare with toxoplasma-negative donor organs, the authors took a closer look.

“We conducted this study because, about a year ago, there was a positive donor and the team did not want to use that kidney for one of our pediatric patients, so we didn’t accept it,” first author Lavjay Butani, MD, chief of pediatric nephrology at the UC Davis Medical Center, Sacramento, California, said in a press statement.

“But we realized, we just didn’t have the data to know if that was the correct decision.”

No Significant Difference in Outcomes

For the study, Butani and colleagues evaluated data from the OPTN database, comparing graft survival on deceased donor kidney transplant recipients based on whether the donor was positive or negative for toxoplasma antibody.

Among 51,422 kidney transplant recipients identified from 2src18 to 2src22, 4317 (8.4%) were from donors who were positive for toxoplasma antibody.

Overall, the rate of acute rejection and graft failure was approximately 5% in each group. The crude rate of graft failure was 7.3 failures per 1srcsrc person-years for toxoplasma-positive donor recipients compared with 6.5 failures per 1srcsrc person-years for toxoplasma-negative donor recipients (P=.srcsrc8), for an adjusted hazard rate ratio of 1.src4 (P=.39) after adjustment for factors including sex, age, ethnicity, and receipt of pretransplant dialysis and other factors.

While not statistically significant, the confidence intervals showed graft failure rates ranging from as much as 5% lower to 15% higher among those with toxoplasma-positive donor organs than among those with toxoplasma-negative donor organs.

With the majority of cases of donor-derived toxoplasmosis typically occurring shortly after transplant, “it is unlikely that follow-up would yield different results,” the authors noted.

“While caution and close monitoring of recipients post-Tx for surveillance of disseminated toxoplasmosis are still warranted, our study suggests that patients can be successfully managed using toxoplasma-positive donor organs,” the authors said.

Routine Post-Transplant Prophylaxis Addresses Infection

Importantly, the current routine use of post-transplant prophylaxis of trimethoprim-sulfamethoxazole (Bactrim) in all patients to prevent pneumocystis is also effective against toxoplasmosis.

With that protective measure, some suggest the need to check for toxoplasma antibody status in non-heart transplant recipients or in geographic areas with a low toxoplasma seroprevalence may not even be necessary, while others recommend close monitoring and follow-up, the authors explained.

When infections do occur, outcomes are typically favorable with early detection and treatment, even in the highest risk groups, they added.

Utilization Varies

While data are lacking on how commonly kidneys from toxoplasma-positive donors are used, Butani commented that “knowing that at our own center in the past we have not used [kidneys from] some of these donors, is an indication to me that this is not uncommon.”

Nevertheless, “it was encouraging to note that transplant from toxoplasma-positive donors occurred in all OPTN regions and in each year under study,” the authors said in the study.

The significance of some geographic and temporal variations is unclear but may represent geographic differences in toxoplasma seropositivity in the United States, “based on sociodemographic factors and unique practices and preferences of centers in accepting such donors,” they noted.

The relatively low percentage of toxoplasma-positive transplants of 8.4% during the study period compares with approximately 11% in the general US population and 17.2% in single-center studies, the authors said.

They added that “transplant centers should re-evaluate their current policy on the acceptance of toxoplasma-positive donor organs in light of recent data and not discard such organs without considering the pros and cons of doing so, for each individual potential transplant recipient.”

With Precautions, Toxoplasma-Positive Donor Kidneys Can Expand Donor Pool

Commenting on the study, Lara Danziger-Isakov, MD, MPH, a pediatrician and director for Immunocompromised Host Infectious Disease at Cincinnati Children’s Hospital, in Cincinnati, agreed that while “concern for potential donor-derived infection exists, with toxoplasmosis serologic screening for all donors, transplant centers can proactively plan monitoring and intervention if needed in transplant recipients.”

Danziger-Isakov added that the study reinforces the safe use of those kidneys from toxoplasma-positive donors.

“With appropriate proactive prophylaxis, monitoring and intervention, donors with positive toxoplasmosis IgG can be safely used in kidney t