Clinical significance of non-Candida fungal blood isolation in patients undergoing high-risk allogeneic hematopoietic stem cell transplantation (1993-2001).

BACKGROUND:

The clinical relevance of mold isolated from blood cultures, even in severely immunosuppressed allogeneic hematopoietic stem cell transplantation (HSCT) recipients, remains uncertain. The authors hypothesized that isolation of non-Candida fungi from blood cultures in patients undergoing high-risk HSCT would have clinical significance.

METHODS:

The authors reviewed the records of 73 allogeneic HSCT recipients between January 1, 1993 and January 1, 2001 in whom fungal species were isolated from blood cultures.

RESULTS:

Fifty-two episodes of non-Candida fungemia occurred in 48 patients (66%) after a median of 10 days (range, 2-341) after transplantation. All 48 patients had indwelling intravascular catheters, and 23 patients (48%) had profound neutropenia. Thirty-five of 48 patients had received partially matched, related donor stem cell grafts (19 patients had 3-antigen-mismatched grafts); 35 patients had undergone T-cell depleted transplantation and 9 patients were receiving treatment for acute graft-versus-host disease. In 5 of 48 patients (10%), death was attributed to fungemia that occurred 8-11 days after the initial fungal blood culture was obtained; all 5 patients were age > 30 years. No deaths occurred in the younger age group (n = 22 patients; P = 0.05). In the 24 patients who did not receive systemic antifungal therapy, 4 deaths (17%) were attributed to infections with Penicillium (n = 2 patients), Epicoccum (n = 1 patient), or Penicillium plus Cladosporium species (n = 1 patient). Of the 24 patients who received amphotericin B, only 1 patient (4%) died as a result of a probable hematogenous Aspergillus species infection; this difference in outcome, however, was not significant (P = 0.2).

CONCLUSIONS:

Most of the non-Candida fungal blood culture isolates in recipients of high-risk, mismatched donor transplantation were clinically nonsignificant. However, because these low-virulence saprophytes occasionally may cause life-threatening disease, a reevaluation of the existing diagnostic paradigm is needed so that clinically significant fungemia may be differentiated from pseudofungemia.