Background: The clinical significance of blood cultures positive for Aspergillus species is unclear. True aspergillemia is rare and has been reported mainly in severely immunocompromised cancer patients with hematologic malignancies. The present study evaluates the clinical significance of positive blood cultures for Aspergillus observed over a 23 year period in a single HSCT center. Methods: We reviewed the blood culture records of all patients who underwent a HSCT at Hôpital Maisonneuve-Rosemont (HMR) between April 1980 and December 2002. Recipients of > 1 HSCT procedure were counted as a different patient. All episodes of positive blood cultures with different microorganisms, and same microorganism episodes at least 7 days apart, were included in the study. Medical records of patients with positive blood cultures with Aspergillus species were reviewed to determine the significance of these positive cultures. Aspergillus fungemia was classified as definite, probable or pseudofungemia according to previously proposed criteria. Results. Over the 23 year period, 1453 patients were transplanted. A total of 939 different episodes of bloodstream infections in 525 (36%) recipients were documented. Of these 525 patients, 377 were identified in recipients of allogeneic transplant and 148 in autologous transplant recipients. Aspergillemia was observed in 8 patients. In all patients the Aspergillus species were recovered from a single blood culture sample and during the period when a lysis centrifugation blood culture system was used. Aspergillus fumigatus was identified in 3 patients. Aspergillus niger in 2 patients, non-speciated Aspergillus in 3 patients. The medical records of 7 patients were available for review. None of the 7 patients had compatible clinical histologic nor microbiologic evidence of invasive aspergillosis. All 7 blood cultures were categorized as pseudofungemia. Conclusion: Positive blood cultures for Aspergillus species is a rare event in HSCT recipients. Even in a high risk population for invasive Aspergillosis, it represented pseudofungemia in our patients, and was likely linked to the potential for environmental contamination of the lysis centrifugation blood culture system.
Full conference title:
14th Annual Focus on Fungal Infections
- FFI 14th (2004)