Endemic and epidemic aspergillosis associated with in-hospital replication of Aspergillus organisms.

When a new hospital opened in 1983, environmental culturing for Aspergillus organisms and surveillance for nosocomial aspergillosis cases were begun to characterize the relationship between environmental contamination and infection. Monthly air sampling demonstrated increasing concentrations of Aspergillus flavus and Aspergillus fumigatus to mean levels greater than 1 cfu/m3 during 1986-1987, accompanied by a progressive increase in incidence of aspergillosis to 1.2% in immunocompromised patients. This prompted an inspection that revealed heavy growth of Aspergillus organisms on air filters. Subsequent inspections of hospital wards showed small foci of A. flavus growth on other materials. Removal of the contaminated filters and improved environmental maintenance were associated with reduction in A. flavus and A. fumigatus to 0.01 cfu/m3 and a fourfold decline in aspergillosis incidence during the next 2 years. These findings, together with laboratory studies that showed aspergilli could proliferate on common hospital materials when moistened, indicate a need for careful environmental maintenance.