Occurrence and hygienic relevance of fungi in drinking water

Fungi, above all filamentous fungi, can occur almost everywhere, even in water. They can grow in such a quantity in water that they can affect the health of the population or have negative effects on food production. There are several reports of fungal growth in water from different countries, but to our knowledge none from Austria so far. The aim of this study was to gain an overview of the spectrum of filamentous fungi and yeasts in drinking water systems. Thirty-eight water samples from drinking water and groundwater were analysed. Fungi were isolated by using membrane filtration and plating method with subsequent cultivation on agar plates. The different taxa of fungi were identified using routine techniques as well as molecular methods. Fungi were isolated in all water samples examined. The mean value for drinking water was 9.1 CFU per 100 ml and for groundwater 5400 CFU per 100 ml. Altogether 32 different taxa of fungi were found. The taxa which occurred most frequently were Cladosporium spp., Basidiomycetes and Penicillium spp. (74.6%, 56.4% and 48.7%, respectively). This study shows that drinking water can be a reservoir for fungi, among them opportunists, which can cause infections in immunosuppressed patients.