Search

Toenail onychomycosis caused by dermatophytes is a significant medical and financial worldwide burden. Relatively scant research has been undertaken as to the predominant species and strains causing this condition in Australia, which is a unique isolated continent with diverse geographical, climatic and population regions. Four regions were selected in Eastern Australia: Far North Queensland, Rural Victoria, Melbourne Metropolitan and Tasmania. From each of these areas, communal nail dust bags from podiatric physicians' work were collected and analysed. A total of 32 dust bags were collected: 10 from Far North Queensland, 8 from Melbourne Metropolitan, 8 from Rural Victoria and 6 from Tasmania. Dermatophyte test medium was used to isolate dermatophytes from the dust, and the colonies were subcultured to Potato Dextrose Agar. Of the bags collected, in total 69% were positive for dermatophytes: 40% from Far North Queensland, 75% from Melbourne Metropolitan, 88% from Rural Victoria and 83% from Tasmania. The internal transcribed spacer (ITS) region of ribosomal DNA was used to identify and compare isolates. A total of 148 dermatophyte strains were identified. The predominant species isolated was Trichophyton interdigitale (125 isolates), which was found in all four regions. This species was further subdivided into four ITS genotypes: the first two were present in all regions, but the third was found only in the Melbourne Metropolitan area and the fourth only in Tasmania. Only one strain of Trichophyton rubrum was found and only in Rural Victoria. Eighteen isolates of Arthroderma quadrifidum were cultured from Rural Victoria and Tasmania and were further classified into three ITS genotypes. Some isolates rarely reported in clinical material were identified as Paraphyton cookei, Arthroderma tuberculatum and Arthroderma crocatum. A potentially new species of Arthroderma was also found in Melbourne Metropolitan. These findings reveal a unique dermatophyte fingerprint in toenails for Eastern Australia.

Trichophyton onychocola is a recently described geophilic dermatophyte that has been isolated from a toenail of Czech patient with a history of onychomycosis due to T. rubrum and clinical suspicion of relapse. In this study, we report a similar case from Denmark in an otherwise healthy 56-year-old man. The patient had a history of great toenail infection caused by T. rubrum in 2004 and presented with suspected relapse in 2011 and 2013. Trichophyton onychocola was the only microbial agent isolated at the second visit in 2013 and the identification was confirmed by DNA sequencing. Direct microscopic nail examination was positive for hyphae, however the etiological significance of T. onychocola was not supported by repeated isolation of the fungus. This new species may be an overlooked geophilic species due to the resemblance to some common species, for example, zoophilic T. interdigitale or some species of geophilic dermatophytes. We included differential diagnosis with phenotypically similar species; however, it is recommended that molecular methods are used for correct identification. The MAT locus of Danish strain was of opposite mating type than in the previously isolated Czech strain and the two isolates were successfully mated. The mating experiments with related heterothallic species T. thuringiense and Arthroderma melis were negative. The sexual state showed all typical signs of arthroderma-morph and is described by using optical as well as scanning electron microscopy. The sexual state was induced on a set of agar media, however low cultivation temperature and the presence of keratin source were crucial for the success rather than formulation of medium., (© The Author 2015. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

A previously undescribed Trichophyton species was isolated from the nail of a 33-year-old man with a history of probable distal lateral subungual onychomycosis (without confirmation by mycological examination). The infection occurred for the first time five years earlier (in 2006) and affected the right great toenail, with complete clinical remission after treatment with ciclopirox olamine. This undescribed species was isolated during probable relapse in 2011, but its etiological significance was not confirmed, that is, direct microscopy was negative and additional clinical samples were not collected. The species is probably geophilic based on phylogenetic analysis (internal transcribed spacer [ITS] rDNA) and is most closely related to the anamorphic T. thuringiense, homothallic Arthroderma ciferrii (anamorph T. georgiae), and heterothallic A. melis. The new species is characterized by yellowish colonies, red reverse on several media, positive urease test, negative hair-perforation test, absence of growth at 34°C, absence of macroconidia, formation of one-celled clavate microconidia, and spiral hyphae. The species grows well on sterilized human hairs placed on agar medium without any additional nutrients and forms gymnothecium-like structures covered by peridial hyphae. The combination of unique micro- and macromorphological features and physiological and sequence data from four unlinked loci (ITS, benA, RPB2, and act1 gene) justified the proposal of a new species T. onychocola sp. nov.

Auxarthron is a genus within the Onygenales encompassing keratinophilic species with typical ascomata (gymnothecia) consisting of anastomosing network of thick-walled hyphae and small globose or oblate ascospores. No association of this genus with clinically relevant cases of human or animal infection has been reported. This paper describes the isolation of an undescribed Auxarthron species as an agent of proven onychomycosis affecting almost all fingernails in a man with psoriasis. The causality of the isolated fungus was verified by repeated sampling and direct microscopy revealing irregular septate hyphae. Based on micro- and macromorphological features and unique sequence data (ITS region, benA and RPB2 gene), the isolated fungus is proposed as the new species A. ostraviense. The sibling species of A. ostraviense, A. umbrinum, was isolated from three patients with suspected onychomycosis and a detailed clinical history is provided for one of these patients. All four isolates were tested for susceptibility to selected antifungal agents. Terbinafine and clotrimazole appear to be effective in vitro. The morphological identification of Auxarthron spp. is non-trivial, time-consuming and requires cultivation media other than Sabouraud glucose agar which is routinely used in dermatomycology.

Chaetomium species have been rarely described as aetiological agents of invasive and dermatomycotic infections in humans. The majority of cases have been reported within the last two decades. Treatment failed in most of these cases. In this paper we present two cases in which Chaetomium spp. can be clearly identified as an aetiological agent in pathological conditions. In the first report, we describe a new aetiological agent, Chaetomium brasiliense, which was implicated in a case of otitis externa in a patient with spinocellular carcinoma basis cranii. The patient had been repeatedly treated for relapsing otitis externa and had previously undergone surgery several times for otitis media. The fungal aetiology was confirmed by repeated positive culture and histologic studies. The second case involved onychomycosis with strikingly brown nail discoloration due to Chaetomium globosum in an otherwise healthy patient. The nail lesion was successfully cured by oral terbinafine. The determination of both species was supported by sequencing of rDNA regions. The morphological aspect of Chaetomium spp. identification is also discussed. In vitro antifungal susceptibility tests demonstrated that both isolates were susceptible to terbinafine and azole derivates except fluconazole. Amphotericin B was effective only against the C. brasiliense strain. We review the literature to summarize clinical presentations, histologic findings, and treatment strategies.