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Patients who received kidneys from Toxoplasma antibody-positive donors had no worse outcomes compared with those who received kidneys from Toxoplasma antibody-negative donors, suggesting that kidneys from these donors are likely to be safe to use, according to a new study.
“Based on the largest study to date investigating outcomes of kidney transplant recipients classified by donor Toxoplasma status, we can reasonably recommend that transplantation of Toxoplasma-positive donors can be performed safely under close monitoring and that such organs should not be discarded reflexively. [some] The authors reported a “caution.” In research Published this month Transplant International.
Toxoplasma gondii is a relatively common parasite that usually causes only mild illness in immunocompromised people, but it can reactivate and cause life-threatening disease.
According to the Organ Donation and Transplant Network (OPTN), the main concern regarding toxoplasmosis transmission is heart transplants, which are at greatest risk.
“Patients who receive heart transplants are at highest risk of infection from the donor, as bacteria tend to live in muscle (including the myocardium),” the organization warns. The guidance“Transplants of other types of organs can also be infected with this pathogen, but at a much lower rate.”
Given the risk, the OPTN requires that all deceased organ donors be tested for toxoplasmosis antibodies, but recommends that the final decision regarding organ acceptance should be left to individual transplant centers.
There was a lack of data showing the extent to which these organs were actually being utilised and how the outcomes compared with Toxoplasma-negative donor organs, so the authors investigated further.
“We did this study because about a year ago we had a positive donor, but the team did not want to use the kidney for one of our pediatric patients and did not accept it,” first author Lovejay Butani, MD, PhD, chief of pediatric nephrology at the University of California, Davis Medical Center in Sacramento, California, said in a press statement.
“But we realized we didn't have the data to know if it was the right decision.”
No significant difference in results
In the study, Butani and colleagues evaluated data from the OPTN database to compare graft survival rates in patients who received kidney transplants from deceased donors based on whether the donor was positive or negative for Toxoplasma antibodies.
Of the 51,422 kidney transplant recipients identified from 2018 to 2022, 4,317 (8.4%) were from Toxoplasma seropositive donors.
Overall, the rates of acute rejection and graft failure were approximately 5% in each group. The crude rate of graft failure was 7.3 events per 100 person-years in Toxoplasma-positive donor-recipients compared with 6.5 events per 100 person-years in Toxoplasma-negative donor-recipients (P = .008), and the adjusted hazard rate ratio was 1.04 (P After adjusting for factors such as sex, age, ethnicity, and pretransplant dialysis status, pretransplant dialysis was associated with a 0.39-fold increased mortality risk.
Although not statistically significant, confidence intervals indicated that the transplant failure rate in people with Toxoplasma-positive donor organs ranged from 5% lower to 15% higher than in people with Toxoplasma-negative donor organs.
Because the majority of donor-derived toxoplasmosis cases typically occur soon after transplant, “follow-up is unlikely to yield different outcomes,” the authors noted.
“Although caution and close monitoring of transplant recipients for disseminated toxoplasmosis remains necessary, our study suggests that patients can be successfully managed with the use of Toxoplasma -positive donor organs,” the authors wrote.
Preventing infections with regular preventive care after transplantation
Importantly, posttransplant trimethoprim-sulfamethoxazole (Bactrim) prophylaxis, now routinely used in all patients to prevent Pneumocystis, is also effective against toxoplasmosis.
This precaution has led some to suggest that testing for Toxoplasma antibody status may not even be necessary in non-heart transplant recipients or in areas with low Toxoplasma seroprevalence, whereas others recommend close surveillance and follow-up, the authors explained.
If infection does occur, early detection and treatment usually results in a good outcome, even for those in the highest-risk groups, the researchers added.
Usage varies
Data is lacking on how commonly kidneys from Toxoplasma-positive donors are used, but Butani said, “I know that we haven't used them in the past at our center, so we're not doing it.” [kidneys from] Some of these donors indicate to me that this is not uncommon.”
Still, “it is encouraging that transplants from Toxoplasma-positive donors occurred in all OPTN regions and in each year studied,” the study authors wrote.
The significance of some of the geographic and temporal variations is unclear but may reflect geographic differences in Toxoplasma seroprevalence in the United States, “based on sociodemographic factors and centers' unique donor acceptance practices and preferences,” the researchers noted.
The rate of Toxoplasma-positive transplants during the study period was relatively low at 8.4%, which compares with approximately 11% in the general U.S. population and 17.2% in the single-center study, the authors note.
They added: “Transplant centers should reevaluate their current policies regarding the acceptance of organs from Toxoplasma-positive donors in light of recent data and should not discard such organs without considering the pros and cons for each potential recipient.”
With precautions, kidneys from Toxoplasma-positive donors could expand the donor pool.
Commenting on the study, Lara Danziger Isakov, MD, MPH, pediatrician and chief of infectious diseases in the immunocompromised host at Cincinnati Children's Hospital, agreed that “while concerns about the possibility of donor-derived infection exist, by conducting serological testing for toxoplasmosis on all donors, transplant centers can proactively plan monitoring and intervention for transplant patients as needed.”
Danziger-Isakov added that the study reinforces the safe use of kidneys from Toxoplasma-positive donors.
“With appropriate prevention, surveillance and intervention, Toxoplasma IgG-positive donors can be safely used as kidney transplant candidates, safely expanding the donor pool.”
The authors and Danziger-Isakov have no disclosures to report.
