Aspergillus terreus: an emerging amphotericin B-resistant opportunistic mold in patients with hematologic malignancies

Abstract

Background: Invasive aspergillosis (IA) has emerged as a common cause of morbidity and mortality among immunocompromised patients. At The University of Texas M. D. Anderson Cancer Center (Houston, TX), Aspergillus terreus is second to A. fumigatus as the most common cause of IA. In the current study, the authors compared the risk factors and outcomes associated with IA caused by A. terreus and IA caused by A. fumigatus.

Methods: The authors retrospectively reviewed the medical records of 300 patients who received care at our institution between 1995 and 2001 and who had cultures that were positive for Aspergillus infection, including 90 patients whose cultures were positive for A. fumigatus and 70 patients whose cultures were positive for A. terreus.

Results: Thirty-two patients with IA caused by A. terreus and 33 patients with IA caused by A. fumigatus were evaluated. The two groups were comparable in terms of age, gender, and underlying disease. Leukemia was the most common underlying malignancy (84%). More than 40% of patients in each group had undergone bone marrow transplantation. There was a trend toward a higher frequency of neutropenia among patients with IA caused by A. terreus (P = 0.12). IA caused by A. terreus was considered to be nosocomial in origin significantly more frequently compared with IA caused by A. fumigatus (P = 0.03). In vitro, A. terreus was found to be more resistant to amphotericin B (minimal inhibitory concentration [MIC90], 4.0 microg/mL) than to antifungal therapy (MIC90, 1.0 Hg/mL) in the isolates that were tested (< 50% of all isolates). The overall rate of response to antifungal therapy was 39% for patients with A. fumigatus infection, compared with 28% for patients with A. terreus infection (P = 0.43).

Conclusions: Despite the decreased in vitro susceptibility of A. terreus (relative to A. fumigatus) to amphotericin B, the two groups within the current patient population had comparably poor responses to amphotericin B preparation and somewhat improved responses to posaconazole.