Fungemia due to Trichosporon dermatis in a patient with refractory Burkitt's leukemia
A 47-year-old female who had suffered from obstructive jaundice and ascites for two months was admitted to our hospital for further examinations. A peripheral blood smear revealed lymphoblastic cells with blue cytoplasm and cytoplasmic vacuoles, and a CT scan showed swelling of multiple lymph nodes in the peritoneal cavity. She was diagnosed as having acute lymphoblastic leukemia of Burkitt's type confirmed by karyotype analysis of a bone marrow aspiration sample showing 47, XX, t(8;14)(q24;q32), +mar in 9 out of 20 cells and FISH analysis of bone marrow showing IgH/c-MYC fusion signals. Combination chemotherapy with rituximab+hyper CVAD followed by high-dose methotrexate/cytosine arabinoside was started using a central venous catheter (CVC), but she could not obtain complete remission (CR) because of early regrowth of lymphoblasts in bone marrow after the induction chemotherapy (). Thereafter, salvage chemotherapy with rituximab+IVAC and rituximab+ CODOX-M was started, but she could not obtain CR because of central nervous system involvement of leukemic cells. Fluconazole (FLCZ) at 200 mg/day had been administered as a prophylactic anti-fungal drug since the start of initial chemotherapy. Three months after the start of chemotherapy, serum βD-gulucan became positive, and the anti-fungal drug was therefore changed from FLCZ to VRCZ because of covering aspergillosis even without characteristic features of aspegillosis shown by a CT scan of the chest and sinus. After that, galactomannan and βD-gulucan remained negative, but she was administered prophylactic VRCZ at 300 mg BID because of transient increase of galactomannan and continuous myelosuppression after repeated chemotherapy (). Nine months after the diagnosis, she suffered from high fever in a severe neutropenic period (white blood cell count of 0.1-0.6×106/L) after salvage chemotherapy. Venous blood culture taken through the CVC showed Corynebacterium species and Trichosporon mucoides (T. mucoides) by a conventional morphological identification method. At that time, both Cryptococcus antigen and βD-gulucan were negative and culture of the removed CVC was also negative. Although the optimal therapy for invasive trichosporonosis is still not known and the identified Trichosporon was susceptible to VRCZ in vitro (MIC was 0.060 µg/mL), clinical anti-fungal effect of the drug was not sufficient. Therefore, VRCZ was switched to L-amphotericin B (L-AMB). Thereafter, Trichosporon species was not identified by repeated venous blood samplings. She died of refractory leukemia 2 weeks after the diagnosis of fungemia by Trichosporon. The stocked isolate was genetically analyzed later and identified as belonging to T. dermatis by DNA sequencing of the intergenic spacer 1 region [].