Opportunistic invasive fungal infections, in particular due to Aspergillus, are an increasing problem in hospitalised immunocompromised patients. These life-threatening infections are an important cause of mortality despite the development of new approaches to therapy. Prevention by the use of effective infection control measures should be a high priority in the management of at-risk patients. Aspergillus spp. are ubiquitous in the environment, and their conidia are easily released and transported in the air. Inhalation of these conidia precedes invasive disease, although in children breeches in the skin and intravenous insertion sites can also serve as port d’entrí©e. Much effort has been taken to filter the air in hospitals to lower the amount of the airborne conidia present. The use of high-efficiency particulate air (HEPA) filtration has been shown to decrease the number of conidia in the air. The reduction in the concentration of airborne conidia is paralleled by a decrease in the frequency of invasive infections, but does not reduce it to zero. Still, the correlation between the concentration of Aspergillus conidia in hospital air and the risk of invasive infections remains unclear. The discovery of hospital water as a potential source of A. fumigatus and other filamentous fungi may suggest a new route for the transmission of S113 New Antifungal Drugs invasive filamentous fungal infections. Although inhalation of airborne conidia is believed to be the primary route of acquiring Aspergillus infection, alternative modes of transmission may be present. Contamination of wounds or the immature, thin skin in very low birth weight infants, by direct inoculation or from the surrounding air, has also been reported, just as aspiration of contaminated surface water in neardrowning patients. The role of using tap water in body care and the possible release of conidia from aerosols during showering needs more attention. Preventive measurements to lower the concentration of conidia in the air by use of HEPA-filtration and/or laminar airflow does not reduce the risk of invasive filamentous fungal infections to zero, and gives rise to suspicion of other sources and routes of transmission. Another argument for the existence of other sources of filamentous fungi and their routes of transmission is the the lack of genetic relatedness between (hospital) environmental strains and those causing invasive diseases. Molecular characterisation and comparison of environmental (water) and clinical isolates must be the next step in order to establish if waterrelated conidia play a role in the pathogenesis of invasive filamentous fungal infections, and in particular of invasive aspergillosis.
Full conference title:
6th Congress of the European Confederation of Medical Mycology Societies
- ECMM 6th (2000)