Species of Scedosporium and Lomentospora are considered as emerging opportunists, affecting immunosuppressed and otherwise debilitated patients, although classically they are known from causing trauma-associated infections in healthy individuals. Clinical manifestations range from local infection to pulmonary colonization and severe invasive disease, in which mortality rates may be over 80%. These unacceptably high rates are due to the clinical status of patients, diagnostic difficulties, and to intrinsic antifungal resistance of these fungi. In consequence, several consortia have been founded to increase research efforts on these orphan fungi. The current review presents recent findings and summarizes the most relevant points, including the Scedosporium/Lomentospora taxonomy, environmental distribution, epidemiology, pathology, virulence factors, immunology, diagnostic methods, and therapeutic strategies.

A monophyletic group of black yeast-like fungi containing opportunistic pathogens around Exophiala spinifera is analyzed using sequences of the small-subunit (SSU) and internal transcribed spacer (ITS) domains of ribosomal DNA. The group contains yeast-like and annellidic species (anamorph genus Exophiala) in addition to sympodial taxa (anamorph genera Ramichloridium and Rhinocladiella). The new species Exophiala oligosperma, Ramichloridium basitonum, and Rhinocladiella similis are introduced and compared with their morphologically similar counterparts at larger phylogenetic distances outside the E. spinifera clade. Exophiala jeanselmei is redefined. New combinations are proposed in Exophiala: Exophiala exophialae for Phaeococcomyces exophialae and Exophiala heteromorpha for E. jeanselmei var. heteromorpha.A significant portion of the species of black yeasts and their filamentous relatives, anamorphs of members of the order Chaetothyriales, are regularly encountered as causative agents of human mycoses (9). They exhibit a relatively high degree of molecular diversity (10) but seem to possess common factors which enable them to invade the human host, resulting in a bewildering diversity of mycoses, such as chromoblastomycosis, mycetoma, brain infection, and other types of phaeohyphomycosis (9). In harboring a wide array of clinically relevant species, the Chaetothyriales are unique in the fungal kingdom: they are only matched by the Onygenales, the order containing the dermatophytes and the dimorphic pathogens. Understanding the species diversity of the Chaetothyriales and their specific ecology is of considerable medical relevance.This wide species spectrum is only poorly understood, as until recently insufficient markers were available for a reliable distinction of taxa. Morphology is poorly developed in these fungi, and when present, very similar microscopic structures can be expressed in phylogenetically remote species (15). Sequencing studies of the ribosomal operon have shown that this gene can be successfully applied to species delimitation and identification. A large number of new taxa have to be introduced; many of these have a pathogenic potential.In an extended 18S ribosomal DNA (rDNA) sequencing study of black yeasts and their allies, Haase et al. (15) showed that the phylogenetic tree of the Chaetothyriales is poorly resolved, which indicates a radiation of taxa within a relatively short evolutionary period. All anamorph genera concerned proved to be polyphyletic (15); the morphological entities were nevertheless maintained for practical reasons. The single teleomorph genus in the order, Capronia, was found throughout the tree but appeared to have limited clinical relevance.

Dormant infections can become reactivated years after having been acquired on another continent.

The PCR assays offer a reliable etiologic diagnosis that is superior to culture in patients with proven invasive mold infection. This may improve patient management through tailored antifungal therapy when cultures fail to grow a pathogen.

Candida dubliniensis is often associated with C. albicans in cultures. Easy-to-perform selective isolation procedures for these closely related species do not exist. Therefore, we evaluated previously described discriminatory phenotypic markers forC. dubliniensis. A total of 150 oral rinses from human immunodeficiency virus (HIV)-infected patients were cultured on CHROMagar Candida. Dark green colonies described as being indicative ofC. dubliniensis and other green colonies, 170 in total, were isolated. Chlamydospore formation, intracellular β-d-glucosidase activity, ability to grow at 42°C, carbohydrate assimilation pattern obtained by the API ID 32C, and Fourier transform infrared (FT-IR) spectroscopy were used for phenotypic characterization. Sequencing of the 5′ end of the nuclear large-subunit (26S) ribosomal DNA gene was used for definitive species identification for C. dubliniensis. C. dubliniensis was found in 34% of yeast-colonized HIV-infected patients. The color of the colonies on CHROMagar Candida proved to be insufficient for selecting C. dubliniensis, since only 30 of 53 provenC. dubliniensis isolates showed a dark green color in primary cultures. The described typical chlamydospore formation can give only some indication of C. dubliniensis. The assimilation pattern proved to be insufficient to discriminate C. dubliniensis from C. albicans. All C. dubliniensis strains showed no or highly restricted growth at 42°C and a lack of β-d-glucosidase activity. Unfortunately, atypical C. albicans strains can also exhibit these phenotypic traits. FT-IR spectroscopy combined with hierarchical clustering proved to be as reliable as genotyping for discriminating the two species.