Waterborne Exophiala species causing disease in cold-blooded animals

Abstract

The majority of mesophilic waterborne species of the black yeast genus Exophiala (Chaetothyriales) belong to a single clade judging from SSU rDNA data. Most taxa are also found to cause cutaneous or disseminated infections in cold-blooded, water animals, occasionally reaching epidemic proportions. Hosts are mainly fish, frogs, toads, turtles or crabs, all sharing smooth, moist or mucous skins and waterborne or amphibian lifestyles; occasionally superficial infections in humans are noted. Cold-blooded animals with strictly terrestrial life styles, such as reptiles and birds are missing. It is concluded that animals with moist skins, i.e. those being waterborne and those possessing sweat glands, are more susceptible to black yeast infection. Melanin and the ability to assimilate alkylbenzenes are purported general virulence factors. Thermotolerance influences the choice of host. Exophiala species in ocean water mostly have maximum growth temperatures below 30 °C, whereas those able to grow until 33(−36) °C are found in shallow waters and occasionally on humans. Tissue responses vary with the phylogenetic position of the host, the lower animals showing poor granulome formation. Species circumscriptions have been determined by multilocus analyses involving partial ITS, TEF1, BT2 and ACT1.

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

“…16), as well as from separate ITS, BT2 and TEF-1 analyses (not shown) Ukrainian specimen of Exophiala belongs to the Exophiala alcalophila branch with the highest level of bootstrap support. Our data confirm the previous results of de Hoog et al (2011) that Exophiala alcalophila belongs to the Exophiala angulospora complex, which is positioned in out-position to the SSU Exophiala salmonis-clade. After our data the Exophiala angulospora complex includes E. angulospora, E. alcalophila, and E. halophila, as well as E. jeanselmei, E. oligosperma, E. xenobiotica, and E. nigra.…”

“…Thus, in contrast to data of de Hoog et al (2011), where Exophiala al calophila formed hyphal structures only on MEA medium, formation of hyphal Kalinichenko 2014, 2015). Exophiala alcalophila found to be well developed on liquid media tested.…”

Fonsecaea pugnacius, a Novel Agent of Disseminated Chromoblastomycosis

“…As shown by comparisons to a selected set of partial LSU rDNA sequences of members of Chaetothyriales available at CBS, the strains under study from a patient with severe chromoblastomycosis and systemic infection were identical and located in a "bantiana clade" (34) containing Fonsecaea species known as agents of chromoblastomycosis, as well as the pathogenic Cladophialophora species C. bantiana, C. arxii, and C. devriesii and the environmental species C. minourae, F. erecta, and F. minima (see Fig. S1 in the supplemental material).…”

Pathologic Findings in Weedy (Phyllopteryx taeniolatus) and Leafy (Phycodurus eques) Seadragons

“…5,8,19,23 Most cases of phaeohyphomycosis were diagnosed by morphology and staining characteristics on light microscopy, although several cases included here were diagnosed by culture and sequencing of PCR-amplified DNA. 19 Similarly, intestinal coccidiosis has been reported to be caused by a novel species of Eimeria in the WSD (Eimeria phyllopterycis).…”