Fatal disseminated Trichoderma longibrachiatum infection in an adult bone marrow transplant patient: species identification and review of the literature

Abstract

Trichoderma longibrachiatum was recovered from stool surveillance cultures and a perirectal ulcer biopsy specimen from a 29-year-old male who had received an allogeneic bone marrow transplant for acute lymphoblastic leukemia. The amphotericin B (2.0 microgram/ml) and itraconazole (1.0 microgram/ml) MICs for the organism were elevated. Therapy with these agents was unsuccessful, and the patient died on day 58 posttransplantation. At autopsy, histologic sections from the lungs, liver, brain, and intestinal wall showed infiltration by branching septate hyphae. Cultures were positive for Trichoderma longibrachiatum. While Trichoderma species have been recognized to be pathogenic in profoundly immunosuppressed hosts with increasing frequency, this is the first report of probable acquisition through the gastrointestinal tract. Salient features regarding the identification of molds in the Trichoderma longibrachiatum species aggregate are presented.

FIG. 1

Methenamine silver stain of the perianal ulcer biopsy specimen shows necrosis and infiltration by branching septate hyphal forms. Magnification, ×100.

FIG. 2

(a) T. longibrachiatum on SDA (left) and PFA (right), 5 days, 25°C. (b) Yellow diffusable pigment produced by T. longibrachiatum on reverse of SDA, 5 days, 25°C.

FIG. 3

Long main branch of T. longibrachiatum producing shorter side branches terminating in phialides. Magnification, ×320.

FIG. 4

Side branches, phialides, and phialoconidia of T. longibrachiatum. Magnification, ×920.

FIG. 5

Terminal phialides (arrows) of T. longibrachiatum. Magnification, ×920.

FIG. 6

Phialoconidia of T. longibrachiatum. Magnification, ×2,300.

FIG. 7

Smooth, thick-walled chlamydoconidia of T. longibrachiatum. Magnification, ×2,300.