Dishwashers e A man-made ecological niche accommodating human opportunistic fungal pathogens P. ZALAR a, *, M. NOVAK a , G. S. DE HOOG b,c,d,e , N. GUNDE-CIMERMAN a,f a Biology Department, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia b Centraalbureau voor Schimmelcultures Fungal Biodiversity Centre, Utrecht, The Netherlands c Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands d Peking University Health Science Center, Research Center for Medical Mycology, Beijing, China e Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China f Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CIPKeBiP), Jamova 39, SI-1000 Ljubljana, Slovenia article info Article history: Received 21 October 2010 Received in revised form 5 April 2011 Accepted 17 April 2011 Available online 7 May 2011 Corresponding Editor: Martin Grube Keywords: Black yeasts Exophiala Human opportunistic pathogen Hygiene Physiology Waterborne fungi abstract Habitats in human households may accommodate microorganisms outside the common spectrum of ubiquitous saprobes. Enrichment of fungi that may require specific environ- mental conditions was observed in dishwashers, 189 of which were sampled in private homes of 101 towns or communities. One-hundred-two were sampled from various local- ities in Slovenia; 42 from other European countries; 13 and 3 from North and South Amer- ica, respectively; 5 from Israel; 10 from South Africa; 7 from Far East Asia; and 7 from Australia. Isolation was performed on samples incubated at 37  C. Species belonging to genera Aspergillus, Candida, Magnusiomyces, Fusarium, Penicillium and Rhodotorula were found occasionally, while the black yeasts Exophiala dermatitidis and Exophiala phaeomuriformis (Chaetothyriales) were persistently and most frequently isolated. Sixty-two percent of the dishwashers were positive for fungi, and 56 % of these accommodated Exophiala. Both Exophiala species are known to be able to cause systemic disease in humans and fre- quently colonize the lungs of patients with cystic fibrosis. We conclude that high temper- ature, high moisture and alkaline pH values typically occurring in dishwashers can provide an alternative habitat for species also known to be pathogenic to humans. ª 2011 British Mycological Society. Published by Elsevier Ltd. All rights reserved. Introduction During the last decade a growing number of biodiversity stud- ies have focussed on remote habitats, like tropical and arid re- gions, and on environments where conditions are considered to be unfavourable for microbial growth. Extreme habitats in general are characterized by low diversity of species that are present with high numbers of individuals. In this respect in- door environments may also be viewed as extreme habitats as only a few hundred fungal taxa have thus far been encoun- tered (Samson et al. 2002). A vast amount of literature is avail- able on the airborne fungal flora in our homes and especially on Aspergillus fumigatus because of its potential impact on hu- man health. Surprisingly, the wet environments in our houses have only recently received attention. Wet cells like bath- rooms, sinks, kitchens and saunas were described as novel niches for adaptation of human pathogens (Hamada & Abe 2010; Lian & de Hoog 2010; Nishimura et al. 1986, 1987). Modern * Corresponding author. Biology Department, Biotechnical Faculty, University of Ljubljana, Ve cna pot 111, 1000 Ljubljana, Slovenia. Tel.: þ386 13203392; fax: þ386 12573390. E-mail address: polona.zalar@bf.uni-lj.si journal homepage: www.elsevier.com/locate/funbio fungal biology 115 (2011) 997 e1007 1878-6146/$ e see front matter ª 2011 British Mycological Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.funbio.2011.04.007