Molecular Identification and Antifungal Susceptibility of Fusarium spp. Clinical Isolates

Accurate identification of Fusarium species requires molecular identification. Treating fusariosis is challenging due to widespread antifungal resistance, high rates of treatment failure, and insufficient information relating antifungal susceptibility to the clinical outcome. Despite recent outbreaks in Mexico, there is limited information on epidemiology and antifungal susceptibility testing (AST).

We aimed to analyse the distribution of Fusarium species from a referral centre in Mexico with DNA sequencing and to describe AST to the clinical outcome.

We conducted a retrospective study on clinical isolates of Fusarium. They were identified by translation elongation factor-1α gene amplification and sequencing. AST was performed to determine minimal inhibitory concentrations (MICs).

A total of 35 Fusarium isolates from 26 patients were included. The most common was Fusarium solani species complex (FSSC) in 51.5%, of which Fusarium petroliphilum and Fusarium oxysporum species complex were the most frequent with 37% and 20%, respectively. AST did not show MICs above the epidemiological cut-off value. Fusariosis was diagnosed in 19 patients, mostly with hematologic neoplasm; the overall mortality rate was 32%.

Fusarium petroliphilum from the FSSC was found most frequently. Elevated mortality and MICs for all tested antifungals were found, with higher MIC50 among F. solani SC than F. oxysporum SC or F. fujikuroi SC.