Invasive Trichosporon cutaneum infection in an infant with wilms' tumor.

Fungal infections are increasingly being reported in immuno-compromised patients. In this study we report a case of systemic Trichosporon cutaneum infection in an infant with Wilms' tumor. This is the first time that an invasive infection for T. cutaneum has been reported in a Wilms' tumor patient.

Deep systemic Trichosporon infection has been observed in association with hematologic malignancy, central venous catheter use, broad-spectrum antibiotics, neutropenia, receiving of anti-neoplastic chemotherapy, immunosuppressive therapy and diminished immune function of various causes (11,15). Though uncommon, trichosporonosis caused by T. cutaneum is frequently fatal (6,12,13). Immuno-compromised hosts are particularly at risk and invasive infection rapidly involves various organs such as the lungs, the kidneys, and the spleen. Cutaneous lesions, a sign of disseminated infection, are also probable (7,15).

Wilms’ tumor is the most common malignant renal neoplasm in an infant (3,8). The tumor commonly presents as an asymptomatic abdominal mass in children between 2 and 4 years old. Due to the ongoing success of clinical trials the overall survival rate is as high as 85% (5). However, opportunistic fungal infections are still a leading cause of death in immunosuppressed patients undergoing intensive chemotherapy (1,9).

A 3-year-old infant with Wilms’ tumor was admitted for treatment to the Osvaldo Cruz University Hospital, Recife, Brazil in 2006. The patient suffered from severe neutropenia and was being treated for a fever with broad-spectrum antibiotics empirically administered.

Three venous blood samples were collected aseptically by venipuncture into VACUTAINER® tubes using EDTA anticoagulant on three consecutive days. They were processed by standard methods for mycological diagnosis (direct examination and isolation in culture) at Medical Mycology Laboratory, Federal University of Pernambuco, Recife.

Direct examination was performed on fresh samples (without clarification and staining) and for isolation, spreading was performed on the surface of Sabouraud agar (Difco) with 0.5 mg of yeast extract/L and 50 mg chloranphenicol/L, and then incubated at between 30°C and 35°C in an aerobic atmosphere for 10 days. After the isolation and culture purification, taxonomic identification was achieved using the recognized macroscopic, microscopic, physiologic and VITEK 120 test methods (4,10).

Diagnostic identification was based on both the presence of septation of hyaline hyphae in the three samples of blood and the isolation of the causal agent T. cutaneum in pure culture in all samples. Microscopic examination showed hyaline, septate hyphae with fragment into arthroconidia cylindrical to ellipsoidal, 2 to 4x3 µ. Blastoconidia were also observed. T. cutaneum colonies are moderately expanding, cerebriform, shiny, not becoming farinose with age, with broad and fissured marginal zones (Fig. 1). T. cutaneum lacks the ability to ferment carbohydrates. It assimilates glucose, galactose, sucrose, maltose and lactose, which distinguishes it from other members of the genus Trichosporon. Potassium nitrate is not utilized, and arbutin is split. The organism was identified as T. cutaneum according to the criteria described by Barnett et al. (2) and Hoog et al. (4).

Figure 1

Direct examination revealed hyphae hyaline-1000x (A) characteristic microscopy of Trichosporon cutaneum 400x (B).

The strain has been maintained under mineral oil (number 5397) at the internationally recognized URM Culture Collection of Department of Mycology, Federal University of Pernambuco, Brazil.

T. cutaneum a saprophytic fungal organism normally found in the soil, is increasingly being recognized as a cause of life-threatening systemic illness in immunosuppressed patients (7, 14). Disseminated T. cutaneum infection, the most significant pathogen in the genus Trichosporon, has a poor prognosis. This report underscores the importance of this infection as a severe condition which is usually fatal when associated with pre-existing conditions such as cancer.