Phenotypic and molecular identification of Fusarium spp. clinical and environmental isolates.

Background: Fusarium is a genus of fungi whose identification is based primarily on phenotypic characteristics, although molecular identification procedures have outperformed conventional procedures. In Mexico, there is no information on the species or complexes of the members of this genus.

Objective: To identify the species of a collection of 116 Fusarium spp. strains obtained from clinical and environmental samples.

Material and methods: Phenotypic identification was carried out by morphology analysis of cultures on the following media: Sabouraud dextrose agar, dextrose potato agar, oat agar, Speziller Nährstoffarmer agar and water agar. Molecular identification was performed by amplification and sequencing of the ITS, TEF1, RPB2 and CL regions.

Results: Only 39 Fusarium strains could be identified at the complex level using phenotypic characteristics. The remaining 77 strains were identified using molecular procedures. In addition, molecular confirmation of identification was sought for the 39 strains already mentioned. ITS sequencing was sufficient for the identification of F. oxysporum and F. solani complex species. For the identification of other species, the sequencing of TEF1, RPB2 and/or CL was required.

Conclusions: Phenotypic identification was often limited by the lack of fungal structure production when cultured on conventional and some minimal media. Molecular procedures are essential to achieve the precise identification of the species of this genus.