The neurotropic black yeast Exophiala dermatitidis has a possible origin in the tropical rain forest

Abstract

The black yeast Exophiala dermatitidis is known as a rare etiologic agent of neurotropic infections in humans, occurring particularly in East and Southeast Asia. In search of its natural habitat, a large sampling was undertaken in temperate as well as in tropical climates. Sampling sites were selected on the basis of the origins of previously isolated strains, and on the basis of physiological properties of the species, which also determined a selective isolation protocol. The species was absent from outdoor environments in the temperate climate, but present at low abundance in comparable habitats in the tropics. Positive outdoor sites particularly included faeces of frugivorous birds and bats, in urban as well as in natural areas. Tropical fruits were found E. dermatitidis positive at low incidence. Of the human-made environments sampled, railway ties contaminated by human faeces and oily debris in the tropics were massively positive, while the known abundance of the fungus in steam baths was confirmed. On the basis of the species' oligotrophy, thermotolerance, acidotolerance, moderate osmotolerance, melanization and capsular yeast cells a natural life cycle in association with frugivorous animals in foci in the tropical rain forest, involving passage of living cells through the intestinal tract was hypothesized. The human-dominated environment may have become contaminated by ingestion of wild berries carrying fungal propagules

New and interesting chaetothyrialean fungi from Spain

“…Therefore, special isolation techniques may be necessary. Previous authors have successfully implemented methods using experimental inoculations in laboratory animals (Gezuele et al 1972;Dixon et al 1980), high incubation temperatures (Sudhadham et al 2008), extraction with mineral oil (Satow et al 2008;Vicente et al 2008), enrichment on atmospheres with aromatic hydrocarbons (Prenafeta-Boldú et al 2001;Zhao et al 2010) and media containing cycloheximide (Salgado et al 2004). In our experience, media with cycloheximide proved to be very useful to isolate members of the Chaetothyriales.…”

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

“…lack yeasts and their filamentous relatives are known to be involved in a wide diversity of clinical pictures, ranging from superficial cutaneous to invasive and disseminated, potentially fatal infections in healthy individuals (1,2). Their environmental counterparts usually live in extreme or toxic environments (3)(4)(5).…”

Glivne okužbe pri bolnikih s cistično fibrozo

“…In parts of the world with a moderate climate it is rarely isolated from nature; it is mostly associated with the human environment, such as spas, saunas and dishwashers. In short, it can be found in a warm and moist environment (35,36). We assume that the original natural habitat of E. dermatitidis is the tropical rainforest (35).…”

“…In short, it can be found in a warm and moist environment (35,36). We assume that the original natural habitat of E. dermatitidis is the tropical rainforest (35).…”