Virulence and biological characteristics of Talaromyces wortmannii isolated from deep-seated dermatomycosis by in vitro and in vivo evaluation.

Background: Talaromyces wortmannii is a ubiquitous saprophytic fungus found in soil, plants, and marine organisms. Infections caused by T. wortmannii in humans are rarely reported, however, a recent case of skin mycosis attributed to this fungus highlights its potential to cause infections under certain conditions. Therefore, studying the biological characteristics of T. wortmannii is crucial for the prevention and control of dermatomycosis.

Methods: T. wortmannii was incubated on different medium and at various temperatures, gathered pertinent data on colony growth and conduct an analysis of its growth characteristics. The Sensititre YeastOne^® and CLSI M38 method was used to determine the minimum inhibitory concentrations (MICs) of amphotericin B, 5-flucytosine, anidulafungin, caspofungin, micafungin, fluconazole, itraconazole, posaconazole, voriconazole and Terbinafine. Finally, the in vivo virulence of T. wortmannii were investigated using Galleria mellonella as an infection model.

Results: The characteristic of T.wortmannii included septate hyphae, occasionally fragmented with varying diameters. Velvety colonies with dense sporulation were observed, grow fastest at 32 °C and displayed a radial growth pattern with a centrally elevated morphology and a slightly depressed margin. The MICs of amphotericin B, itraconazole, posaconazole and voriconazole were relatively low, suggesting potential clinical efficacy. A greater number of deaths occurred at higher inoculum levels. Both the T.wortmannii clinical strain F22-1-C5 and standard strain CGMCC3.17703 exhibits virulence towards the larvae.

Conclusions: T. wortmannii can cause human infections. Amphotericin B, itraconazole, posaconazole, and voriconazole may be effective for treatment of such infectoins.