Indoor wet cells harbour melanized agents of cutaneous infection

Abstract

The biota of black fungi in humid indoor environments was established using a protocol that consisted of non-selective and selective isolation procedures. In total, 113 samples were taken from bathrooms of residences in The Netherlands, Germany and Austria. Samples were processed either (i) directly by culturing on agar media, or (ii) by pre-incubating samples for enrichment in mineral solutions with perlite granules under constant toluene atmosphere for three months. Dilutions from the latter were then cultured and incubated as were those directly plated to agar media. Black colonies were selected and identified by sequencing the rDNA Internal Transcribed Spacer (ITS) region. Twenty-eight strains of black fungi were found in 26 positive samples without enrichment, and 42 strains were isolated from 38 positive samples after enrichment in toluene. The great majority of black fungal species were members of the order Chaetothyriales, which is the main order of melanized human opportunistic pathogens. Cladosporium species (Capnodiales) were the most frequent isolates when no enrichment was applied, as opposed to Exophiala species (Chaetothyriales) with enrichment. The enrichment method provides insight into a fungal biota commonly occurring in homes which has previously been overlooked. Several species have been previously known only from cutaneous infections and could suggest that bathrooms are a likely reservoir of these fungi.

Identification and Typing of Isolates of Cyphellophora and Relatives by Use of Amplified Fragment Length Polymorphism and Rolling Circle Amplification

“…Their environmental counterparts usually live in extreme or toxic environments (3)(4)(5). However, only recently we began to realize that black yeast-like fungi are all around in outdoor and indoor, man-made environments, such as railways, bathrooms (6,7), steam baths (8), and dishwashers (9). They are frequently overlooked because they grow slowly, require dedicated isolation methods, and are difficult to diagnose by morphology.…”

Confirmation of taxonomic status of black yeast-like fungus by three gene phylogeny

“…Data on morphology of colonies, conidiogenous structures were compared with recent publications (de Hoog et al 2011, Lian andde Hoog 2010).…”

“…The appearance of human skin infections suggested to be connected with the presence of black yeasts in the rooms, including the bathrooms (i.e. sensu "water systems" rooms) (Lian and de Hoog 2010). These fungi thought to be also associated with many kinds of diseases of wildlife, including fish, marine toads, turtles, shellfish .…”

“…Wet cells like bathrooms, sinks, kitchens and saunas were described as novel niches for adaptation of human pathogens (Hamada 2013, Hamada and Abe 2010, Lian and de Hoog 2010, Nishimura et al 1987. Bathwater and sludge of bathroom drainpipes are important habitats for members of the genus Exophiala (Hamada and Abe 2010, Matos et al 2002, Nishimura et al 1987.…”

Who lives in our dishwasher? Preliminar results of fungal metagenomic analysis of household dishwashers

“…al (2011) have shown that this includes the dishwasher. Actually, most fungi are not dangerous, but some types can be harmful, like oligotrophic black fungi, which have been potential to cause human infection (Lian & de Hoog, 2010), or for example, Exophiala dermatitidis, which can cause potentially fatal systemic and brain infections (Zeng et al, 2007). Furthermore, fungi have also been implicated in the sick building syndrome (Straus, 2009;Thrasher & Crawley, 2009).…”