Timely Diagnosis of Disseminated Toxoplasmosis by Sputum Examination

Abstract

The diagnosis of disseminated toxoplasmosis in a 14-year-old allogeneic bone marrow recipient with graftversus-host disease was determined by the detection of Toxoplasma gondii tachyzoites in sputum smears. Sputum analysis is a valuable alternative in the clinical assessment of pulmonary toxoplasmosis, especially when conventional invasive techniques are not practicable. CASE REPORTA 14-year-old girl had been transplanted with human lymphocyte antigen-identical allogeneic hematopoietic stem cells from an unrelated donor because of a T-cell lymphoma. Her pretransplant serological tests were positive for Toxoplasma gondii (immunoglobulin G [IgG] ϭ 60 IU/ml, IgM negative). The donor's Toxoplasma serology was negative. The recipient received polyclonal immunoglobulin for passive immunoprophylaxis and cyclosporine and methylprednisolone for graftversus-host disease (GvHD) prophylaxis. She developed acute GvHD, and mycophenolate mofetil was added to her previous therapy on day 97 posttransplantation. On day 113, she presented with fever, cough, dyspnea, pancytopenia, and elevated levels of C-reactive protein. There were interstitial infiltrates in both lungs seen in chest computed tomography images (CT). All diagnostic tests for cytomegalovirus, adenovirus, and Pneumocystis, Aspergillus, and Legionella spp. were negative. The patient's condition worsened despite probabilistic anti-infective treatment with ceftriaxone, teicoplanin, and caspofungin. A central tricytopenia prompted repeated transfusions. On day 123, she developed headache and vomiting. The fundus examination was normal. The brain CT showed a hypodense area on the right side of the thalamus. Her respiratory status deteriorated with severe hypoxemia requiring oxygen therapy.Diff-Quick-stained cytospin-prepared sputum smears (Microscopy Hemacolor MERCK catalog no. 65044-93) showed tachyzoites suggestive of Toxoplasma gondii (Fig. 1). T. gondii was detected with specific direct immunofluorescence tests on both bone marrow and sputum specimens. Real-time PCR targeting a repetitive 529-bp DNA fragment of T. gondii (GenBank accession no. AF487550) was positive in both blood and sputum samples.A treatment combining pyrimethamine (50 mg daily after a 100-mg loading dose) and sulfadiazine (1,250 mg four times daily) was initiated, and the patient steadily improved. Blood and sputum specimen collected after 14 days of treatment were negative for T. gondii PCR. There was progressive hematological reconstruction (as evidenced by blood numeration) and a reduction in size of the brain lesion on the CT. The girl was discharged from hospital after 20 days of pyrimethamine-sulfadiazine treatment.

Prevention of toxoplasmosis in transplant patients

“…Cell culture offers the possibility of reducing this delay, but is no longer used for diagnosis, since the development of DNA‐based diagnostic methods. PCR techniques, the most sensitive of which involve the repeated B1 and AF146527 gene targets, have markedly changed the strategy for diagnosis and treatment of transplant recipients [42,64–68]. Moreover, the use of real‐time PCR avoids the risk of false positivity due to DNA carryover [65], and allows quantification of T. gondii DNA to monitor treatment efficacy [50].…”

Successful treatment of toxoplasmic encephalitis diagnosed early by polymerase chain reaction after allogeneic hematopoietic stem cell transplantation: two case reports and review of the literature

“…Toxoplasmosis is a rare, but potentially life‐threatening opportunistic infection, with an estimated mortality rate of 60–90%, after allogeneic hematopoietic stem cell transplantation (allo‐SCT) , and has been attributed to the reactivation of latent Toxoplasma gondii infection . The seroprevalence of T. gondii varies markedly among different regions, ranging from 10% to 50–80%; 10% in Japan, <15% in the United States, and 50–80% in Central Europe .…”

Severe Pulmonary Toxoplasmosis Mimicking Viral Pneumonitis after a Third Allogeneic Stem Cell Transplantation in a Man with Acute Lymphoblastic Leukemia

“…However, PCR for T. gondii is a time-consuming method because it is not performed routinely in Japan. Laibe et al reported a case of disseminated toxoplasmosis diagnosed using a Diff-Quick-stained sputum smear analysis (16). Sputum is readily obtainable, even from severely ill patients, and its analysis can be performed immediately.…”