FINAL DIAGNOSIS: -- DISSEMINATED TRICHOSPORON BEIGELII
THERAPY: -- Systemic therapy included liposomal amphotericin B and intravenous fluconazole, as well as intraocular antifungal therapy. The patient remained in remission of his leukemia during hospitalization and was discharged one month after admission on oral fluconazole and metronidazole.
Trichosporon beigelii belongs to the family Cryptococcaceae. This species was formerly known as Trichosporon cutaneum, as it is the etiologic agent of "white piedra," a mild superficial infection of head and pubic hair shafts, most often seen in tropical climates and rarely in temperate areas (1,2). It is widely distributed in the soil of many climates; and it is occasionally found as normal flora of the skin and gastrointestinal tracts. In a normal, healthy individual, T. beigelii is considered a commensal organism rather than a pathogen.
In immunocompromised individuals, however, commensal fungi can cause severe, life-threatening disseminated disease. While the majority of these infections are due to Candida and Aspergillus species, trichosporonosis (including species T. beigelii, T. capitatum, and Geotrichum capitatum) is emerging as an important cause of invasive, disseminated mycoses in these individuals (3). The most likely primary source of the infection is the patient's own gastrointestinal and respiratory flora (3).
Disseminated trichosporonosis has been reported in recipients of solid organ transplants (4,5), but most cases occur in severely neutropenic individuals who have undergone chemotherapy for hematologic malignancies and in recipients of bone marrow transplants (6,7). To date, it has not emerged as a common pathogen in those with AIDS. The presence of a prosthetic heart valve and hemochromatosis are additional risk factors for disseminated disease (3).
The presentation of trichosporonosis can be acute or chronic. Acute disease presents over several days, often with nodular skin lesions, pulmonary infiltrates, generalized malaise and anorexia, fever, and changes in vision. Chronic disseminated disease generally presents with progressive debilitation and a persistent fever unresponsive to wide-spectrum antibiotics. Hepatosplenomegaly and abscess formation within the lungs, liver, kidneys and spleen are common.
Diagnosis of disseminated disease is predicated on clinical suspicion and confirmed by culture and histologic examination of biopsy tissue. Trichosporon species is morphologically distinct from Candida species, with the presence of arthroconidia and occasional septated hyphae in addition to blastoconidia and pseudohyphae. T. beigelii is unique in its overall inability to ferment but ready ability to assimilate numerous sugars. T. beigelii does not utilize potassium nitrate (8).
Individuals with disseminated trichosporonosis carry a grave prognosis despite aggressive antifungal therapy; nearly 75% succumb to their infection. The main prognostic factor is recovery of immunocompetency. Amphotericin B is active against many fungal infections, but it has limited activity against Trichosporon species (9). In individuals with persistent profound neutropenia, treatment with azole compounds alone will likely lead a poor response, and the combination of amphotericin B and fluconazole is recommended (10). The efficacy of miconazole and itraconazole is, as yet, poorly defined. It has been suggested that prophylactic fluconazole for patients at risk for trichosporonosis is likely to reduce infection by this organism (10). It is important to note, however, that clinical experience with azole therapy in trichosporonosis has been rather limited, and larger-scale studies are warranted.
Contributed by Karen K. Deal, MD., PhD, N. Paul Ohori, MD , and A William Pasculle, ScD