Aspergillus: An Increasing Problem in Tertiary Care Hospitals?

Sir—We analyzed the microbiologic laboratory data regarding isolation of Aspergillus species from clinical specimens of patients hospitalized at the Detroit Medical Center from 1994 through 1998, and identified a steady increase in the number of Aspergillus isolates recovered (figure 1). Duplicate isolates from the same patients were few (<5%). Of the 423 isolates, 284 (66%) were Aspergillus fumigatus. Common non-fumigatus species were Aspergillus flavus and Aspergillus niger. The isolates included those that caused disease as well as colonizers and contaminants. Mere presence of Aspergillus species in clinical specimens does not imply invasive disease. Invasion must, however, be strongly suspected in certain settings such as neutropenia and bone marrow transplantation [1, 2]. Most source patients were immunocompromised children and adults (i.e., cancer patients, marrow transplant recipients, AIDS patients, and those receiving immunosuppressive agents). Aspergillus species isolates from patients hospitalized at the Detroit Medical Center, 1994–1998. Solid bars, Aspergillus fumigatus; open bars, non-fumigatus aspergillus. Our data suggest that the incidence of aspergillosis may be on the rise at our medical center. A large retrospective study of aspergillosis conducted at a transplant center has observed a similar trend [3]. There may be several reasons for this increase: an increase in the number of immunocompromised hosts in the hospital setting, a heightened awareness of aspergillosis among clinicians that causes them to perform more fungal diagnostic tests and so detect fungal infections more often in clinical specimens, better fungal isolation techniques in the laboratory, and/or an increase in the number of building construction sites around hospitals. Another contributing factor may be the recent availability of triazoles (e.g., fluconazole) for better treatment of and prophylaxis for candidal infections.