Phylogenetic diversity of human pathogenic Fusarium and emergence of uncommon virulent species

- Phylogenetic analysis of 44 clinical Fusarium isolates revealed eleven species and the etiological agents belonged to four species complexes.
- Site of infections were blood, cornea, skin, wound, burns and nails.
- Our findings agree with the suggested variable local distributions of opportunistic Fusarium species and indicate that especially F. acutatum is an endemic species in the Middle East.
- Comorbidities associated with invasive infections were hematological malignancy and autoimmune disorders. Mortality was 66.7% for the blood infections irrespective of antifungal chemotherapy and was associated with Fusarium petroliphilum and Fusarium solani.
- F. solani species complex predominantly cause cornea, nail and bloodstream infections. Fast and more accurate molecular diagnostic tests to species level may contribute to an earlier and more precise diagnosis and subsequently optimized treatment.

SummaryObjectivesFusarium species cause a broad spectrum of infections. However, little is known about the etiological agents to the species level. We identified Fusarium species isolated from clinical specimens including those of high risk patients to better understand the species involved in the pathogenesis.MethodsA set of 44 Fusarium isolates were identified by two-locus sequence typing using partial sequences of the second largest subunit of RNA polymerase (RPB2) and translation elongation factor 1 alpha (TEF-1α).ResultsThe identified species belonged to four species complexes (SC); the most common SC was Fusarium solani (FSSC) (75%), followed by Fusarium oxysporum (FOSC) (4.5%), Fusarium fujikuroi (FFSC) (13.6%), and Fusarium dimerum (FDSC) (6.8%). Sites of infections were nails (n = 19, 43.2%), skin (n = 7, 15.9%), cornea (n = 6, 13.6%), blood (n = 3, 9%), wound (n = 4, 6.8%), burn (n = 2, 4.5%), tissue (n = 2, 4.5%), and urine (n = 1, 2.27%). Fusarium acutatum was rare and seem restricted to the Middle East. Comorbidities associated with invasive infections were hematological malignancy and autoimmune disorders.ConclusionsMembers of the FSSC predominantly caused cornea, nail and bloodstream infections. Less frequently encountered were the FOSC, FFSC and FDSC. More accurate molecular identification of Fusarium species is important to predict therapeutic outcome and the emergence of these species.