Cerebral toxoplasmosis after haematopoietic stem cell transplantation

Guidelines for the management of Toxoplasma gondii infection and disease in patients with haematological malignancies and after haematopoietic stem-cell transplantation: guidelines from the 9th European Conference on Infections in Leukaemia, 2022

Patients with haematological malignancies might develop life-threatening toxoplasmosis, especially after allogeneic haematopoietic stem-cell transplantation (HSCT). Reactivation of latent cysts is the primary mechanism of toxoplasmosis following HSCT; hence, patients at high risk are those who were seropositive before transplantation. The lack of trimethoprim-sulfamethoxazole prophylaxis and various immune status parameters of the patient are other associated risk factors. The mortality of toxoplasma disease-eg, with organ involvement-can be particularly high in this setting. We have developed guidelines for managing toxoplasmosis in haematology patients, through a literature review and consultation with experts. In allogeneic HSCT recipients seropositive for Toxoplasma gondii before transplant, because T gondii infection mostly precedes toxoplasma disease, we propose weekly blood screening by use of quantitative PCR (qPCR) to identify infection early as a pre-emptive strategy. As trimethoprim-sulfamethoxazole prophylaxis might fail, prophylaxis and qPCR screening should be combined. However, PCR in blood can be negative even in toxoplasma disease. The duration of prophylaxis should be a least 6 months and extended during treatment-induced immunosuppression or severe CD4 lymphopenia. If a positive qPCR test occurs, treatment with trimethoprim-sulfamethoxazole, pyrimethamine-sulfadiazine, or pyrimethamine-clindamycin should be started, and a new sample taken. If the second qPCR test is negative, clinical judgement is recommended to either continue or stop therapy and restart prophylaxis. Therapy must be continued until a minimum of two negative PCRs for infection, or for at least 6 weeks for disease. The pre-emptive approach is not indicated in seronegative HSCT recipients, after autologous transplantation, or in non-transplant haematology patients, but PCR should be performed with a high level of clinical suspicion.

Detection and treatment of cerebral toxoplasmosis in an aplastic pediatric post-allogeneic hematopoietic cell transplant patient: a case report

BACKGROUND

Cerebral toxoplasmosis infection presents with non-specific neurologic symptoms in immunocompromised patients. With lack of measurable adaptive immune responses and reluctance to sample affected brain tissue, expedient diagnosis to guide directed treatment is often delayed.

CASE PRESENTATION

We describe the use of cerebrospinal fluid polymerase chain reaction and plasma cell-free DNA technologies to supplement neuroimaging in the diagnosis of cerebral toxoplasmosis in an immunocompromised pediatric patient following allogeneic hematopoietic cell transplantation for idiopathic severe aplastic anemia. Successful cerebral toxoplasmosis treatment included antibiotic therapy for 1 year following restoration of cellular immunity with an allogeneic stem cell boost.

CONCLUSIONS

Plasma cell-free DNA technology provides a non-invasive method of rapid diagnosis, improving the likelihood of survival from often lethal opportunistic infection in a high risk, immunocompromised patient population.

Multiple Reactivations of Viral Infections Followed by Cerebral Toxoplasmosis After Allogeneic Hematopoietic Stem Cell Transplantation in an Adolescent With Ph(+) Acute Lymphoblastic Leukemia: A Case Report

After allogeneic hematopoietic stem cell transplantation (allo-HSCT), especially from an unrelated donor, infectious complications are frequent and severe, sometimes with fatal outcomes. Despite using highly sensitive molecular techniques for close monitoring in the early post-transplant period for early diagnosis, not every viral infection or reactivation can be detected adequately early, even with highly sensitive methods. Particularly after toxic and deeply immunosuppressive treatment, multiple infections or reactivations, uncommon infections, or infections in unusual locations can occur. Here, we present a case of multiple viral infections or reactivations and cerebral toxoplasmosis in a 17-year-old youth with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) treated with allo-HSCT who suffered multiple viral infections followed by cerebral toxoplasmosis.