Molecular identification and antifungal susceptibility of Curvularia australiensis, C. hawaiiensis and C. spicifera isolated from human eye infections.

A reliable identification method was developed for three closely related Curvularia species, which are frequently isolated from human keratomycoses. Since the traditionally used morphological method and the increasingly used internal transcribed spacer (ITS)-based molecular method proved to be insufficient to discern C. australiensis, C. hawaiiensis and C. spicifera, other molecular targets, such as β-tubulin, translation elongation factor 1-α and the nuclear ribosomal intergenic spacer (IGS), were tested. Among them, the use of the highly divergent IGS sequence is suggested and the species-specific discriminating characters were determined in appropriate reference strains. It was also concluded that C. hawaiiensis and C. spicifera can be predominantly isolated from eye infections among the three species. The in vitro antifungal susceptibility of 10 currently used antifungal agents against 32 Curvularia isolates was also investigated. MICs were determined in each case. Isolates of C. spicifera proved to be less susceptible to the tested antifungals than those of C. hawaiiensis, which underline the importance of the correct identification of these species.