Molecular Phylogenetic Diversity of Dermatologic and Other Human Pathogenic Fusarial Isolates from Hospitals in Northern and Central Italy

Abstract

Fifty-eight fusaria isolated from 50 Italian patients between 2004 and 2007 were subject to multilocus DNA sequence typing to characterize the spectrum of species and circulating sequence types (STs) associated with dermatological infections, especially onychomycoses and paronychia, and other fusarioses in northern and central Italy. Sequence typing revealed that the isolates were nearly evenly divided among theFusarium solanispecies complex (FSSC;n= 18), theF. oxysporumspecies complex (FOSC;n= 20), and theGibberella(Fusarium)fujikuroispecies complex (GFSC;n= 20). The three-locus typing scheme used for members of the FSSC identified 18 novel STs distributed among six phylogenetically distinct species, yielding an index of discrimination of 1.0. Phylogenetic analysis of the FOSC two-locus data set identified nine STs, including four which were novel, and nine isolates of ST 33, the previously described widespread clonal lineage. With the inclusion of eight epidemiologically unrelated ST 33 isolates, the FOSC typing scheme scored a discrimination index of 0.787. The two-locus GFSC typing scheme, which was primarily designed to identify species, received the lowest discrimination index, with a score of 0.492. The GFSC scheme, however, was used to successfully identify 17 isolates asF. verticillioides, 2 asF. sacchari, and 1 asF. guttiforme. This is the first report thatF. guttiformecauses a human mycotic infection, which was supported by detailed morphological analysis. In addition, the results of a pathogenicity experiment revealed that the human isolate ofF. guttiformewas able to induce fusariosis of pineapple, heretofore its only known host.