Dishwashers provide a selective extreme environment for human-opportunistic yeast-like fungi

Abstract

Urban life has led to the creation of human-made environments that, from a microbiological perspective, provide extreme life conditions. Certain non-ubiquitous microorganisms such as thermophilic members of the black yeast genus Exophiala are enriched within these habitats for which no counterpart is known in nature. Dishwashers consistently accumulate a number of specific black, white and red yeasts on the rubber seals of doors and in stagnant water at the interior. Several of these yeasts are primarily known as agents of human opportunistic infections. In this review, the literature data are supported by a screening study involving 937 households in 15 cities in Turkey. Fungi were detected in 230 samples (24.5 %). Using rDNA sequencing, the prevalent species were identified as Exophiala dermatitidis (n = 116), Candida parapsilosis (n = 44), E. phaeomuriformis (n = 35), Magnusiomyces capitatus (n = 22), Rhodotorula mucilaginosa (n = 15), and C. lusitaniae (n = 14). The possible role of dishwashers in transmitting disease is discussed.