The significance of isolation of saprophytic molds from the lower respiratory tract in patients with cancer

Abstract

BACKGROUND: Invasive infections caused by molds other than Aspergillus, Fusarium, and Zygomycetes have been reported sporadically in patients with leukemia and allogeneic bone marrow transplantation (BMT). However, the significance of lower respiratory tract cultures that are positive for these saprophytic molds in an unselected population of patients with cancer remains unclear. METHODS: The authors evaluated the significance of respiratory specimens positive for saprophytic molds in patients with cancer using the criteria set by the European Organization for Research and Treatment of Cancer (EORTC)/Mycoses Study Group (MSG). They included the diagnostic category of indeterminate pulmonary invasive mold infection (IMI) for cases that met the criteria for probable IMI but had other pathogens concomitantly isolated from the respiratory tract. RESULTS: Eighty-five cases with at least 1 positive culture were identified in 79 patients. Two cases were proven IMI, 29 were indeterminate IMI, 5 were possible IMI, and 49 were no IMI. All 38 cases from patients with solid tumors represented colonization compared with only 11 of the 47 cases (23%) from high-risk patients (P < 0.0001). The positive predictive value (PPV) of cultures was 0% in patients with solid tumors and ranged from 4.3% to 76.6%, depending on the analytic model used, in high-risk patients with leukemia and recipients of BMT. Cultures positive for Scedosporium spp. had a higher PPV (9.1-100%) than did cultures positive for non- Scedosporium spp. (2.8- 69.4%). CONCLUSIONS: Adjustments of the EORTC/MSG criteria may be required for the diagnosis of invasive infections caused by saprophytic molds, especially non-Scedosporium spp., in patients with cancer.