Molecular identification and in vitro susceptibility of Fusarium from fungal keratitis in central China

Abstract

To detect the genotypes and in vitro antifungal susceptibility of Fusarium isolated from patients with fungal keratitis in central China. Partial translation elongation factor (EF) 1-α of 758 strains of Fusarium isolated from patients with fungal keratitis in Henan Eye Institute during 2002 to 2011 were sequenced. Species and genotypes of Fusarium were identified by conducting BLAST searches of the Fusarium ID database with partial EF1-α sequences as the query. The minimum inhibitory concentrations (MIC) of vorionazole, ketoconazole, terbinafine, natamycin, 5-flucytosine, fluconazol, amphotericin B, nystatin, econazole, clotrimazole, miconazole and itraconazole to 145 isolates of Fusarium were determined by microbroth dilution method according to Clinical Laboratory Standards Institute (CLSI) M38-A program. Among the 758 strains of Fusarium isolates, species of 653 strains were identified. 99.69% of the Fusarium strains were identified by EF1-asequences as Fusarium solani species complex (FSSC), Fusarium oxysporum species complex (FOSC) and Gibberella fujikuroi species complex (GFSC), 0.31% as Fusarium sp. Among the 653 isolates from cornea, FSSC was the predominant Fusarium, 386 isolates (59.11%), with 43 genotypes. The most common seen FSSC genotype was FSSC5-d (132/20. 21%), followed by FSSC3+4-eee (58/8.88%), FSSC3+4-ii (37/5.67%) and FSSC3+4-z (31/4.75%). The second complex was GFSC, 254 isolates (38.90%), with 3 species which were F.proliferatum (124 strains/18.99%), F.verticillioides (112 strains/17.15%) and GFSC (18 strains/2.76%) respectively. The third complex was FOSC, 11 (1.68%) strains, with 6 genotypes. The results of in vitro drug sensitivity test showed that Fusarium strains were sensitive to natamycin, vorionazole and amphotericin B, resistant to 5-fluorocytosine, fluconazole, nystatin, clotrimazole, miconazole. More than 50% of Fusarium strains were sensitive to econazole, ketoconazole, itraconazole and terbinafine. The MIC50 of FSSC to vorionazole, miconazole, terbinafine, Econazole and natamycin was higher than that of F.verticillioides, F.proliferatum and GFSC respectively. The predominant Fusarium complex of fungal keratitis in central China was FSSC, followed by GFSC. 43 genotypes were included in FSSC in which the most common seen FSSC genotype was FSSC5-d, followed by FSSC3+4-eee, FSSC3+4-ii and FSSC3+4-z. GFSC contained 3 species which were F.proliferatum, F.verticillioides and GFSC respectively. Different genotypes of Fusarium from keratitis had different susceptibility to vorionazole, terbinafine, natamycin and miconazole.