Invasive aspergillosis: clusters and sources?

Clusters of invasive infection with Aspergillus fumigatus are known to be associated with building works but studying the epidemiology has been hampered by the lack of a reliable typing system. A combination of three typing systems; silver staining of sodium dodecyl sulphate-polyacrylamide gels, immunoblot fingerprinting, and random amplification of polymorphic DNA (RAPD) was applied to seven cases on a haematology unit. The results show three of the patients to have indistinguishable isolates, suggesting a common source. Detection and removal of such sources, although difficult, would be an effective way of controlling the infection.