Successful toxoplasmosis prophylaxis after orthotopic cardiac transplantation with trimethoprim-sulfamethoxazole1

Background. The efficacy of trimethoprim-sulfamethoxazole (TMP/SMX) in the prevention of toxoplasmosis after orthotopic cardiac transplantation has been the subject of some controversy, with many transplant groups preferring to use the combination of pyrimethamine and sulfadiazine. Although effective, this latter regimen does not offer equal protection against other pathogens, such as Nocardia or Listeria. To assess the value of TMP/SMX, we reviewed the experience in our heart transplant patients, all of whom received TMP/SMX (160/800 mg) three times weekly for approximately 8 months after transplantation. Methods. We report on 417 orthotopic cardiac transplants during a 17-year period. We have 100% one-year patient follow-up after transplantation. Data was collected on pretransplantation donor and recipient anti-Toxoplasma serology, immunosuppression, allograft rejection, survival, yearly posttransplantation anti-Toxoplasma serology, development of acute toxoplasmosis, and the occurrence of other infections. Results. In this cohort, acute toxoplasmosis developed after transplantation in one case (0.2%). Among the highest risk patients (D+R-) who were treated for at least one episode of rejection, the risk of acute toxoplasmosis was 5% (1 of 22 patients). No change in survival was found between the different anti-Toxoplasma IgG serogroups (D-R-, D-R+, D+R-, or D+R+). Anti-Toxoplasma IgG seroconversion occurred in eight Toxoplasma-seronegative recipients after transplantation; all patients, except the case already noted, were asymptomatic and required no specific anti-Toxoplasma therapy. No cases of Listeria, Nocardia, or Salmonella infections were identified. Five proven and two suspected cases of Pneumocystis carinii pneumonia were found (only 2 of these 7 patients were receiving TMP/SMX at the time of Pneumocystis carinii pneumonia diagnosis). Conclusions. These data demonstrate that TMP/SMX prophylaxis (160/800 mg) three times per week is effective Toxoplasma prophylaxis after orthotopic cardiac transplantation and has prophylactic benefits against other posttransplantation opportunistic pathogens.