Sampling of Aspergillus spores in air

Nosocomially acquired aspergillosis typically occurs in the setting of trea tment for leukaemia or other haematological malignancy. As Aspergillus spec ies can be readily found in the environment, it has been widely believed th at aspergillosis occurs as a consequence of exogenous acquition of the fung us. Stringent environmental controls in transplant units have included high -efficiency air filtration, positive-pressure ventilation and frequent room air changes. Although there have been several well-documented examples of aspergillosis outbreaks as a result of hospital demolition and reconstructi on, it has not always been possible to demonstrate elevated spore counts in clinical areas during building work. The sampling of air for Aspergillus i s very problematic. Careful attention must be given to the design of air sa mpler, sampling protocols and an understanding of air sampling data. This r eview outlines many of the physical and environmental parameters that influ ence meaningful air sampling and recommends a simple procedure that has bee n tried and tested in many aspergillosis outbreaks. (C) 2000 The Hospital I nfection Society.