Fusarium spp. have frequently been isolated from patients with onychomycosis. In Colombia, several studies have shown that Fusarium is the most common non-dermatophyte mould causing onychomycosis and its spread has increased in the past years. In this study, samples were collected in 2003 and 2004 from 137 patients who were diagnosed with onychomycosis caused by Fusarium spp. Three species of Fusarium were identified: Fusarium solani (64.9%), Fusarium oxysporum (32.8%) and Fusarium verticillioides (2.3%). The diseases were more common in women (73%) than in men (27%) and occurred mainly among adults between 31 and 40 years old. The percentage of patients who had received previous treatments was 63.5%. In the last years, new and improved antifungal agents like echinocandins or new triazoles like voriconazole have been developed. For this reason, susceptibility testing using voriconazole was performed, by broth microdilution and disk diffusion. The results showed that F. solani had the highest minimum inhibitory concentration. Using the disk diffusion test, many of the isolates showed variable susceptibility. Genetic diversity of F. oxysporum isolates was determined by random amplified polymorphic DNA. Twenty isolates belonging to different haplotypes were selected for PCR amplification of a region of the gene encoding α-l-arabinofuranosidase B, a specific test to determine if the isolates were F. oxysporum f. sp. dianthi. On the basis of these PCR results, we found that five out of the 20 F. oxysporum isolates corresponded to f. sp. dianthi.

Fusariosis have been increasing in Colombia in recent years, but its epidemiology is poorly known. We have morphologically and molecularly characterized 89 isolates of Fusarium obtained between 2010 and 2012 in the cities of Bogotá and Medellín. Using a multi-locus sequence analysis of rDNA internal transcribed spacer, a fragment of the translation elongation factor 1-alpha (Tef-1α) and of the RNA-dependent polymerase subunit II (Rpb2) genes, we identified the phylogenetic species and circulating haplotypes. Since most of the isolates studied were from onychomycoses (nearly 90 %), we carried out an epidemiological study to determine the risk factors associated with such infections. Five phylogenetic species of the Fusarium solani species complex (FSSC), i.e., F. falciforme, F. keratoplasticum, F. lichenicola, F. petroliphilum, and FSSC 6 as well as two of the Fusarium oxysporum species complex (FOSC), i.e., FOSC 3 and FOSC 4, were identified. The most prevalent species were FOSC 3 (38.2%) followed by F. keratoplasticum (33.7%). In addition, our isolates were distributed into 23 haplotypes (14 into FOSC and nine into FSSC). Two of the FSSC phylogenetic species and two haplotypes of FSSC were not described before. Our results demonstrate that recipients of pedicure treatments have a lower probability of acquiring onychomycosis than those not receiving such treatments. The antifungal susceptibility of all the isolates to five clinically available agents showed that amphotericin B was the most active drug, while the azoles exhibited lower in vitro activity.

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