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

Background and Purpose

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.

Materials and Methods

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.

Results

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.

Conclusion

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.

Lasiodiplodia theobromae onychomycosis among agricultural workers: A case series

Lasiodiplodia theobromae is a dematiaceous non-dermatophyte mold (NDM), rarely reported to cause onychomycosis. Here, we report three cases of toenail onychomycosis caused by L. theobromae in agricultural workers. Two patients presented with total dystrophic onychomycosis and one with distal and lateral subungual onychomycosis. These cases have unique importance that besides traumatized nail infection, its rarity has adversely affected the agricultural workers livelihood as L. theobromae sporulates poorly, resistant to commonly used antifungal therapy. From the literature search, we assume that this is the first case series of onychomycosis caused by L. theobromae from a tropical country like India.

Pestalotioid fungi: A rare agent of onychomycosis among agriculture workers

Background and Purpose:

Pestalotioid fungi are ubiquitous environmental molds that have received considerable attention in recent times not only because of their role as a plant pathogen but also owing to their high frequency of retrieval from human diseases. Regarding this, the present study was conducted to investigate onychomycosis caused by pestalotioid fungi, commonly considered important phytopathogens causing grey blight disease in Camellia sinensis.

Materials and Methods:

A total of 122 agriculture workers were enrolled from Assam, India. Direct microscopic examination was carried out using 40% KOH to determine the presence of any fungal element. Further processing of the specimens for the isolation of fungi was performed using the standard protocol. In addition, the keratinolytic potential of the isolates was evaluated by means of the in vitro hair perforation test.

Results:

Out of 103 culture-positive samples, non-dermatophyte and dermatophyte molds constituted 82.52% (n=85) and 6.79% (n=7) of the samples, followed by yeasts (n=1, 0.9%) and sterile hyphae (n=10, 9.7%). With regard to the isolated non-dermatophyte molds (82.69%), 4 cases belonged to pestalotioid fungi, such as Neopestalotiopsis piceana (n=1), Pestalotiopsis species (n=1), and Pseudopestalotiopsis theae (n=2). The keratinolytic activity of Pestalotiopsis species showed perforation by disrupting the hair cortex; furthermore, macroconidia were found to be present inside the human hair.

Conclusion:

A high rate of NDM isolation may be attributed to constant exposure to adverse environmental and occupational hazards. This study highlighted the importance of “pestalotioid fungi” as the rare etiologic agent of onychomycosis. Another remarkable finding was the keratinolytic potential of Pestalotiopsis species, which is unique in this study.