Hematological unit invasive aspergillosis epidemiology

Invasive aspergillosis (IA) is a major cause of morbidity and mortality among the immunocompromised, especially those undergoing hematopoietic stem cell transplantation. With spore inhalation the usual infection route, such subjects must be protected from environmental spore contamination, necessitating measures such as high-efficiency particulate air (HEPA) filtration. In April 2006, we implemented a new transplantation unit with HEPA filtration. We retrospectively evaluated its efficacy for hospitalized transplantation unit subjects whose sera were tested for aspergillus galactomannan antigen between April 2004 and March 2007. Subjects numbered 265 (973 samples) categorized as definite, probable, or possible. The earliest IA onset date was when symptoms, positive radiological findings, or positive galactomannan antigen tests occurred, based on revised European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) definitions. We classified cases when IA occurred over 10 days after admission as hospital-acquired. No such cases were detected after November 2005 and IA incidence decreased significantly after the new unit began being used. Results suggest that the new unit and HEPA filtration helped eliminate nosocomial IA.