# Onychomycosis caused by dematiaceous fungi: A four-year study on agricultural workers of Assam, India

## TL;DR

This study examines onychomycosis caused by dematiaceous fungi among agricultural workers in Assam, India, and evaluates antifungal drug effectiveness.

## Contribution

The study highlights the increasing role of dematiaceous fungi in onychomycosis and provides antifungal susceptibility data for better treatment strategies.

## Key findings

- Dematiaceous fungi, particularly Pestalotiopsis spp. and Arthrinium spp., were frequently isolated from onychomycosis cases.
- Azoles, amphotericin-B, and anidulafungin showed strong antifungal activity against the tested isolates.
- Non-dermatophytic molds accounted for 52% of fungal infections in the studied population.

## Abstract

Onychomycosis caused by dematiaceous fungi is rarely reported and the identification is also quite tricky due to poor sporulation. Recent emergence of dematiaceous fungi as a major cause of onychomycosis is a matter of concern in the field of mycology. Therefore, this study aimed to understand the dematiaceous fungi as a possible cause of onychomycosis, especially among agricultural workers. In addition, the evaluation of the antifungal susceptibility patterns led to the idea of an accurate drug that will help to treat and prevent antifungal resistance.

The standard procedure was followed for direct microscopic examination and fungi isolation. Furthermore, antifungal susceptibility testing was conducted in accordance with the Clinical and Laboratory Standards Institute M-38-A2 protocol

Both potassium hydroxide and fungal positivity were found in 275 out of 356 suspected cases, 52%, 4.3%, 28.7%, and 14.9% of which were non-dermatophytic molds (NDMs), yeast, dermatophytes,
and sterile hyphae, respectively. Among NDMs (52%, n=143), 45.5% (n=65) were hyaline hyphomycetes and 54.5% (n=78) were dematiaceous hyphomycetes.
Among dematiaceous fungi, Pestalotiopsis spp. and Arthrinium spp. were the commonly isolated ones. Additionally, azoles, amphotericin-B, and anidulafungin showed excellent antifungal activity against tested isolates.

Dematiaceous fungi are now becoming a potential cause of onychomycosis. A more detailed study is needed on the identification of these emerging isolates and the mode of action of antifungal drugs for a better treatment strategy.