Epidemiological study of Fusarium species causing invasive and superficial fusariosis in Japan

Abstract

In Japan, Fusarium species are known etiological agents of human fungal infection; however, there has been no report of a large-scale epidemiological study on the etiological agents of fusariosis. A total of 73 Fusarium isolates from patients with invasive fusariosis (IF, n = 36) or superficial fusariosis (SF, n = 37), which were obtained at hospitals located in 28 prefectures in Japan between 1998 and 2015, were used for this study. Fusarium isolates were identified using Fusarium- and Fusarium solani species complex (FSSC)-specific real-time PCR and partial DNA sequences of the elongation factor-1 alpha (EF-1α) gene and the nuclear ribosomal internal transcribed spacer (ITS)region. FSSC was predominately isolated from both patients with IF and SF (IF, 77.8% and SF, 67.6%). Distribution of the phylogenetic species of FSSC isolates from patients with IF and SF exhibited different spectra; specifically, F. keratoplasticum (FSSC 2) (25.0%)was the most frequent isolate from patients with IF, whereas F. falciforme (FSSC 3+ 4) (32.4%)was the most frequent isolate from patients with SF. Fusarium sp. (FSSC 5)was the second most frequent isolate from both patients with IF and SF (IF, 22.2% and SF, 24.3%). Notably, F. petroliphilum (FSSC 1)was isolated only from patients with IF. Each species was isolated from a broad geographic area, and an epidemic was not observed. This is the first epidemiological study of Fusarium species causing IF and SF in Japan.