Keratinophilic fungi from selected soils of Bahrain

Dermatophytosis caused by Nannizzia nana (Microsporum nanum): a comprehensive review on a novel pathogen

Keratinophilic fungi are mostly soil-inhabiting organisms with occasional infections in humans and animals. Even though most dermatophytes are host-adapted, cross-species infections are common by zoophilic and geophilic dermatophytes. N. nana is considered an etiological agent of ringworm in pigs but has also been isolated from other animals, including humans. However, it also possesses many characteristics of geophilic dermatophytes including the ability to grow in soil. N. nana produces characteristic pear-shaped macroconidia and usually exhibits an ectothrix pattern of hair infection. It has been isolated from dermatitis lesions as well as from soil. N. nana infections in pigs are not of much concern as far as economy or health is concerned. But it has been associated with onychomycosis and gonathritis in humans, which are significant in human medicine. The shift in the predominance of dermatophytes in humans and the ability to evolve into a potential tinea pathogen necessitates more understanding of the physiology and genetics of N. nana. In this review, we have attempted a detailed analysis of the studies about N. nana, emphasizing growth and cultural characters, physiology, isolation, infection in humans and animals, molecular characterization and antifungal susceptibility.

Molecular systematics of Keratinophyton: the inclusion of species formerly referred to Chrysosporium and description of four new species

Four new Keratinophyton species (Ascomycota, Pezizomycotina, Onygenales), K. gollerae, K. lemmensii, K. straussii, and K. wagneri, isolated from soil samples originating from Europe (Austria, Italy, and Slovakia) are described and illustrated. The new taxa are well supported by phylogenetic analysis of the internal transcribed spacer region (ITS) region, the combined data analysis of ITS and the nuclear large subunit (LSU) rDNA, and their phenotype. Based on ITS phylogeny, within the Keratinophyton clade, K. lemmensii is clustered with K. durum, K. hubeiense, K. submersum, and K. siglerae, while K. gollerae, K. straussii and K. wagneri are resolved in a separate terminal cluster. All four new species can be well distinguished from other species in the genus based on phenotype characteristics alone. Ten new combinations are proposed for Chrysosporium species which are resolved in the monophyletic Keratinophyton clade. A new key to the recognized species is provided herein.

DNA sequence analysis of keratinophilic fungi isolated from livestock stables in the East of Iran

BACKGROUND AND PURPOSE

Keratinophilic fungi play an important role in the decomposition of keratinous substances in nature. This capacity induces dermatomycosis in both humans and livestock. The soil of livestock stables can be a reservoir of keratinophilic fungi. Therefore, the present study was conducted to isolate and identify keratinophilic fungi in the soil of the livestock stables located in Qayen, South Khorasan Province, Iran.

MATERIALS AND METHODS

This study was conducted on 62 soil samples collected from livestock stables. The samples were cultured by means of hair bait technique (HBT). The identification of the isolates was performed based on their morphological characteristics and then confirmed by polymerase chain reaction and sequencing of the ITS regions of ribosomal DNA.

RESULTS

A total of 118 isolates of 7 species from 5 genera were identified. Aphanoascus verrucosu (n=70, 59.36%) was detected as the dominant keratinophilic fungus, followed by Arthroderma quadrifidum (n=13, 11.01%), A. terreus (n=12, 10.16%), Acremonium (n=12, 10.16%), A. gertleri (n=5, 4.23%), Fusarium equiseti (n=3, 2.54%), and Uncinocarpus reesii (n=3, 2.54%).

CONCLUSION

Different keratinophilic fungi were isolated from the soil of livestock stables; however, A. verrucosu was found to be the dominant species.

Keratinophilic fungi: Specialized fungal communities in a desert ecosystem identified using cultured-based and Illumina sequencing approaches

Soil fungi in desert ecosystems are adapted to harsh environmental conditions such as high soil surface temperatures and limited organic matter and water. Given limited carbon inputs from plant material, heterotrophic fungi likely use unconventional sources of carbon in these systems. A baiting method was used to culture keratinophilic fungi from biocrust and rhizosphere soils in an arid grassland in Utah, USA. Fungi were baited using llama and sheep wool, horsehair, and snakeskin on two media, and pure cultures were identified using ITS and LSU rRNA sequences. One hundred-eighteen fungal colonies were grown, representing a total of 32 Operational Taxonomic Units (OTUs) at 97 % similarity. Cultures were dominated by the phylum Ascomycota (88 %) followed by Mucoromycota (8.6 %) and Basidiomycota (3.4 %). The orders Pleosporales, Eurotiales, Hypocreales, and Sordariales were commonly isolated, with the dominant taxa Alternaria (27 %), Aspergillus (22 %), Fusarium (11 %), and Chaetomium (8%). Thirty percent of the fungi isolated have the capacity to degrade keratin in vitro using a keratin azure assay, with Penicillium showing the highest degradation followed by Geomyces, Alternaria, and Fusarium. Although keratin degraders can be infectious, dermatophytes associated with skin infections were not isolated in culture or detected in Illumina sequencing. Illumina sequencing was used to determine general patterns in seasonal variation and habitat preference of keratinophiles. Alternaria was the most abundant genus with >70 % of the sequences. The combination of Illumina data with culture-dependent approaches facilitated the characterization of a specialized community and confirmed the low abundance of dermatophytes in this arid site.

Distribution of Keratinophilic Fungi in Soil Across Tunisia: A Descriptive Study and Review of the Literature

Data on the frequency and distribution of keratinophilic fungi in soil of Tunisia are scanty. The present survey aimed to describe the distribution of keratinophilic fungi in soils collected in Tunisia. Keratinophilic fungi were isolated using Vanbreuseghem's hair-baiting technique from 354 soil samples collected in 15 governorates of Tunisia and identified according to their morphology with further DNA and MALDI-TOF analysis when necessary. Keratinophilic fungi were isolated from 46.3 % of the samples from 14 governorates. Chrysosporium keratinophilum was the predominant species (30.5 %) followed by Microsporum gypseum (27.4 %). Other isolated species included C. tropicum (14.0 %), C. indicum (11.0 %), Chaetomium sp. (4.9 %), Arthroderma curreyi, Arthroderma cuniculi (3.7 % each), C. merdarium (3.1 %), Anixiopsis stercoraria, C. parvum, Paecilomyces lilacinus, Auxarthron zuffianum (2.4 % each), Fusarium oxysporum, Aphanoascus verrucosus, Gymnascella dankaliensis (1.2 % each) and 12 other species (0.6 % each). Two to five distinct fungal species were associated with 11.5 % of the positive samples. Keratinophilic fungi were more frequently isolated in rural (54.8 %) than in urban (41.1 %) areas (p = 0.012). The highest (100 %) positive culture rate was noted in soil collected in stables. Keratinophilic fungi are frequent throughout Tunisian territory, particularly in soils with a high organic matter content that should be regarded as humans and animals mycoses reservoir.

Isolation and molecular identification of keratinophilic fungi from public parks soil in Shiraz, Iran

Introduction. Keratinophilic fungi are an important group of fungi that live in soil. The aim of this study was to isolate and identify keratinophilic fungi from the soil of different parks in Shiraz. Materials and Methods. A total of 196 soil samples from 43 parks were collected. Isolation of the fungi was performed by hair bait technique. The isolated colonies were identified by morphologic feature of macro- and microconidia and molecular method, using DNA sequence analysis. ITS region of ribosomal DNA was amplified and the PCR products were sequenced. Results. 411 isolates from 22 genera were identified. Fusarium (23.8%), Chrysosporium (13.13%), Acremonium (12.65%), Penicillium (12.39%), Microsporum gypseum (1.94%), Bionectria ochroleuca (1.21%), Bipolaris spicifera (1.21%), Scedosporium apiospermum (0.82%), Phialophora reptans (0.82%), Cephalosporium curtipes (0.49%), Scedosporium dehoogii (0.24%), Ochroconis constricta (0.24%), Nectria mauritiicola (0.49%), Chaetomium (0.49%), Scopulariopsis (0.24%), Malbranchea (0.24%), and Tritirachium (0.24%) were the most important isolates. Most of the fungi were isolated from the soils with the PH range of 7 to 8. Conclusion. Our study results showed that many keratinophilic fungi isolated from the parks soil are important for public health and children are an important group at a high risk of being exposed to these fungi.

Epidemiological investigation of keratinophilic fungi from soils of Djerba (Tunisia)

INTRODUCTION

Epidemiological investigation of keratinophilic fungi in soil has been carried out in different parts of the world. However, our knowledge of the present occurrence and distribution of keratinophilic fungi in Tunisian soils remains unknown. This study was carried out to evaluate the epidemiological characteristics of keratinophilic fungi in the soils collected in Djerba (South of Tunisia).

MATERIAL AND METHODS

One hundred and forty one soil samples were collected from various sites in Djerba and screened for the presence of keratinophilic fungi and related dermatophytes using hair-baiting technique. Fungi were identified using macro- and micro-morphological features.

RESULTS

Among them, 29 (20.6%) soil samples were positive. Seven species were isolated in the following order of dominance: Chrysosporium keratinophilum (48.3%), Microsporum gypseum (41.4%), C. tropicum (10.4%), C. parvum (3.45%), C. anamorph of Anixiopsis stercoraris (3.45%), C. anamorph of Arthroderma cuniculi (3.45%) and Chaetomium sp. (3.45%). The association of M. gypseum and C. keratinophilum was detected in 13.8% of positive soils. Sixty-nine percent of fungi were found in organic matter rich soil. Our results revealed a higher prevalence of keratinophilic fungi in the regions far from the sea (33.3%) than in those near the sea (11.1%) with a statistically significant difference (P=0.001). All keratinophilic fungi were isolated from soils with pH ranging from 6.2 to 7.6.

CONCLUSION

Our study showed that keratinophilic fungi were present in the various soils of Djerba. They may represent a risk to human health.

Keratinophilic fungi isolated from soils of long-term fold-grazed, degraded pastures in national parks of Slovakia

A total of 939 isolates of 11 genera representing 15 species of keratinophilic fungi were isolated and identified from the soils of three long-term fold-grazed pastures in national parks of Slovakia (Pod Ploskou, Strungový príslop, and Pod Kečkou) and one non-fold-grazed pasture in sierra Stolicke vrchy (Diel) using the hair-baiting technique. Keratinophilic fungi were present in all soil samples with a prevalence of Trichophyton ajelloi and Paecilomyces lilacinus. These fungi were more abundant in soil from fold-grazed pasture (Strungový príslop) compared to non-fold-grazed pasture (Diel). The occurrence of the other keratinophilic fungi was substantially lower, likely because of low pH in some soils.