Trichophyton equinumvar.Autotrophicum; Its characteristics and geographical distribution

ITS barcodes forTrichophyton tonsuransandT. equinum

Early molecular biosystematic studies of dermatophytes created considerable confusion about the taxonomic status of the horse-associated Trichophyton equinum vis-à-vis the anthropophilic T. tonsurans. Though this matter has recently been clarified, routine identification of these species based on the commonly used ribosomal internal transcribed spacer (ITS) sequence has been impractical. This is because, in the available sequences attributed to the species in GenBank, a clear species-level distinction does not appear to exist. In the present study, resequencing the ITS regions of several anomalous isolates is shown to eliminate this problem, which was mainly based on read errors in older sequences. Newly generated sequences and recent GenBank additions are analysed to show that T. equinum appears to be uniform in ITS sequence worldwide, while T. tonsurans is also uniform, excepting a single-base change found in one otherwise typical strain. Analysis also reveals a distinct, as yet incompletely classified Asian genotype that may belong to one or the other of these species. Standard ITS 'barcode sequences' are proposed for T. tonsurans and T. equinum, and a taxonomic neotype is designated to anchor the latter species. T. equinum var. autotrophicum is further evidenced as very closely related to T. equinum var. equinum, and the anomaly of its plesiomorphous phenotype is discussed in a population genetics context.

Molecular taxonomy of Trichophyton mentagrophytes and T. tonsurans

Most members of the anamorph genus Trichophyton are anthropophilic and have evolved with the human host. Classical parameters for the identification of dermatophytes include clinical features, cultural characteristics, conidial morphology and physiological test results. Phenotypic variability and pleomorphism due to culturing on artificial media is common among this group of organisms and has led to the description of numerous species. The validity of taxa around T. mentagrophytes and T. tonsurans was verified. Morphological and physiological features were compared to results of three different molecular techniques (sequencing of the internal transcribed spacer (ITS) region of the ribosomal operon, PCR fingerprinting and amplified fragment length polymorphism (AFLP) analysis). Twenty-four species or varieties investigated could be reduced to five taxa and were reclassified or synonymized as Trichophyton tonsurans, T. interdigitale, T. mentagrophytes, T. simii and T. erinacei.

Human onychomycosis caused by Trichophyton equinum transmitted from a racehorse

We report fingernail onychomycosis caused by Trichophyton equinum in a farmer who breeds racehorses. In addition to the thumbnail, T. equinum had infected one of the racehorses. Oral terbinafine cured the infection in the farmer.

Review of animal mycoses in Australia

This review covers the available literature on the mycoses of animals in Australia since the last review published in 1967. Of the cutaneous infections, dermatophytoses have been recorded in a wide range of animals: cattle, horses, goats, pigs, sheep, cats, dogs, mice, guinea-pigs, rabbits, a lion, kangaroos, a camel, koalas and wallabies. These infections were caused by several species and varieties of the genera, Microsporum and Trichophyton. Eight agents of ringworms have been recorded in the horse. Two subcutaneous mycoses, phaeohyphomycosis and sporotrichosis have been reported. Phaeohyphomycosis is becoming more common but sporotrichosis is rare having been recorded only once in a cat. The following systemic mycoses have been recorded: adiaspiromycosis, aspergillosis, candidiasis, cryptococcosis, dactylariosis, fusariomycosis, histoplasmosis, miscellaneous mycoses, mycotic abortion and related conditions, zygomycosis, pythiosis, protothecosis and green algal infections. Cryptococcosis has affected 11 different animal species. Mycotic abortion is a serious disease in Victoria. Pythiosis of horses has been extensively studied in northern Australia.

Zoophilic dermatophytes and their natural hosts in Western Australia

Zoophilic dermatophytes were a common source of both human and animal ringworm infections in Western Australia. Microsporum canis was the chief aetiologic agent of infections in kittens and children. Trichophyton mentagrophytes was isolated from domestic pets, farm animals, laboratory animals and wild animals as well as humans. T. verrucosum was a less frequent cause of infection in both man and animals. Other zoophilic species isolated included M. Gypseum, M. nanum and T. equinum var. autotrophicum.

The epidemiology of ringworm in racehorses caused by Trichophyton equinum var autotrophicum

The epidemiology of dermatomycocis due to Trichophyton equinum var autotrophicum was studied in a number of thoroughbred stables in south-east Queensland. The significant factors in the epidemiology were defined. The infection was readily transmitted, particularly by infected saddle-girths, on which the fungus could survive for 12 months. Mild abrasion from the saddle during work favoured the development of lesions and prolonged the recovery period. A pronounced age and seasonal incidence of the disease was demonstrated as young horses under the age of 3 years were most susceptible, and the majority of cases occurred in periods of high humidity.

Superficial mycoses in a southern New Zealand district

A total of 2,709 pathogenic fungi were isolated from 8,762 patients suspected as having mycotic disease, over an 8 year period in Christchurch, New Zealand. The district is climatically designated as temperate with average mean temperatures of 17 degrees C in summer and 8 degrees C in winter. The predominant species of fungi were relatively small in number with Trichophyton mentagrophytes var. interdigitals as the major pathogen. Fungi other than true dermatophytes, particularly Candida spp. and Malassezia furfur, were included to demonstrate the full spectrum of superficial mycoses presenting for diagnosis at the mycology clinic.