German-Wide Analysis of the Prevalence and the Propagation Factors of the Zoonotic Dermatophyte Trichophyton benhamiae.

For about 10 years, a new variant of the pathogen Trichophyton (T.) benhamiae has appeared in Germany, characterized by a previously unobserved culture phenotype with a strong yellow reverse. A few studies suggest that this new variety is now the most common zoophilic dermatophyte in Germany. The guinea pig is the main carrier. Exact prevalence measurements are not yet available. Thus, the aim of our ongoing study was to collect data on the frequency and geographic distribution of the pathogen and its phenotypes (white and yellow) in humans and guinea pigs throughout Germany. Our former studies have already shown that animals from large breeding farms are particularly heavily affected. In contrast to this, 21 small, private breedings were sampled and husbandry conditions recorded. This placed us in a position to identify propagation factors and to give recommendations for containment. For animals from private breedings, we detected T. benhamiae with a prevalence of 55.4%, which is a reduction of nearly 40% compared with animals from large breeding farms. As risk factors, we identified the type of husbandry and the contact to other breedings. Furthermore, certain animal races, like Rex guinea pigs and races with long hair in combination with curls were predestined for colonization with T. benhamiae due to their phenotypic coat characteristics. A prevalence for infections with T. benhamiae of 36.2% has been determined for symptomatic pet guinea pigs suspected of having dermatophytosis and is comparable to the study of Kraemer et al. showing a prevalence of 34.9% in 2009 in Germany. The prevalence in humans is stable with about 2-3% comparing the data of 2010-2013 and 2018 in Thuringia. The new type of T. benhamiae was by far the most frequent cause in all settings.

Trichophyton mentagrophytes - a new genotype of zoophilic dermatophyte causes sexually transmitted infections.

BACKGROUND: A new genotype of the zoophilic fungal species Trichophyton (T.) mentagrophytes was recently described in two studies. It was isolated from three patients who had visited Southeast Asia and one patient who had visited Egypt. In contrast to these studies, we have observed a number of cases with the dimensions of an epidemic outbreak. PATIENTS AND METHODS: At the University Hospital Charité Berlin, 43 patients, mostly suffering from highly inflammatory, painful and persistent infections of the pubogenital region were observed between January 2016 and July 2017. Mycological examination was performed with fungal culture and sequencing of the ITS (internal transcribed spacer) region of the ribosomal DNA. Three additional genomic regions were spot-checked. RESULTS: In 37 of the cases, a new genotype of T. mentagrophytes (referred to here as T. mentagrophytes VII) was isolated as the etiological agent, and sequencing revealed identical sequences for all isolates. Most of the infected patients had no history of travel, and only two patients reported contact with animals. CONCLUSIONS: The new genotype clustered phylogenetically among the strains of the zoophilic species T. mentagrophytes with four different DNA markers. While human-to-human transmission of zoophilic dermatophytes is rare, transmission via sexual contact seemed to be quite effective here.

Unequal distribution of the mating type (MAT) locus idiomorphs in dermatophyte species.

The mating type (MAT) locus is the key regulator of sexual reproduction in fungi. In the dermatophytes and other Ascomycetes this genomic region exists in two distinct forms (idiomorphs) and their balanced presence is a precondition for successful mating in heterothallic fungi. But the MAT locus not only drives sexual reproduction, it has also been shown to influence pathogenicity, virulence, and/or morphological changes in pathogenic fungi of the genera Candida, Histoplasma, and Cryptococcus. In order to find out whether there are similar trends in dermatophytes, we investigated the MAT locus of 19 anthropophilic and zoophilic species via Sanger sequencing and primer walking. We identified for the first time the MAT locus idiomorphs of the dermatophyte species Microsporum audouinii (MAT1-2), M. ferrugineum (MAT1-2), Trichophyton schoenleinii (MAT1-2), T. bullosum (MAT1-1), T. quinckeanum (MAT1-1), T. concentricum (MAT1-1), T. eriotrephon (MAT1-1), and T. erinacei (MAT1-2). In addition, we determined the MAT locus sequence for dermatophyte species whose mating type idiomorphs had been described on the basis of results of classical confrontation experiments (e.g. M. canis, MAT1-2) and we confirmed recently published molecular data (e.g. T. rubrum, MAT1-2). Our results corroborate that MAT locus idiomorphs are unequally distributed in the majority of the analyzed species and the ability to mate with a partner of the opposite sex is limited to a few zoophilic species. Clonal spreads are identified that are connected to one of the idiomorphs and a higher virulence and/or a higher transmission rate to humans (T. benhamiae and T. mentagrophytes). For the imbalanced idiomorph distribution pattern we hypothesize that either: (I) one of the mating type idiomorphs may be extinct due to clonal reproduction (e.g., T. rubrum and M. canis), (II) mating partners of one species adapted to different hosts followed by speciation in the new niche (e.g., T. equinum and T. tonsurans) or (III) unisexual reproduction is the next evolutionary stage of propagation in dermatophytes which involves the extinction of one mating idiomorph.

New insights in dermatophyte research.

Dermatophyte research has renewed interest because of changing human floras with changing socioeconomic conditions, and because of severe chronic infections in patients with congenital immune disorders. Main taxonomic traits at the generic level have changed considerably, and now fine-tuning at the species level with state-of-the-art technology has become urgent. Research on virulence factors focuses on secreted proteases now has support in genome data. It is speculated that most protease families are used for degrading hard keratin during nitrogen recycling in the environment, while others, such as Sub6 may have emerged as a result of ancestral gene duplication, and are likely to have specific roles during infection. Virulence may differ between mating partners of the same species and concepts of zoo- and anthropophily may require revision in some recently redefined species. Many of these questions benefit from international cooperation and exchange of materials. The aim of the ISHAM Working Group Dermatophytes aims to stimulate and coordinate international networking on these fungi.

Trichophyton verrucosum infection in livestock in the Chitral district of Pakistan.

INTRODUCTION: Trichophyton verrucosum belongs to the dermatophyte fungi, closely related organisms that cause skin infections in animals and humans. T. verrucosum infection has been reported in livestock and people in different countries from all continents. Human cases have been reported in different areas of Pakistan, but there is little information about the animal source of the fungus. METHODOLOGY: Dermatological specimens collected in the Chitral district of Pakistan for a study on mange in livestock were retrospectively analyzed for the presence of T. verrucosum. In total, 5,873 animals (1,087 cows, 2,033 goats, and 2,753 sheep) were screened for evidence of dermatological lesions during two surveys performed in the summer and winter seasons. Skin scrapings collected from animals with lesions were analyzed by direct microscopic examination after digestion in sodium hydroxide and a real-time polymerase chain reaction (PCR) targeting pathogenic Trichophyton species. RESULTS: At microscopy, samples from 18 cows (1.6%), 3 sheep (0.1%), and 4 goats (0.2%) were positive for fungal elements consistent with T. verrucosum. PCR confirmed the microscopy results. The prevalence was lower than that reported in other countries in intensive breeding farms. Results agree with the literature regarding factors affecting T. verrucosum diffusion, i.e., infection was more prevalent in cattle, especially in younger animals during the winter season. CONCLUSIONS: This study reports, for the first time, the presence of T. verrucosum in livestock in Pakistan. A better knowledge of the animal role in the spread of this fungus may allow the adoption of more efficient control measures and prophylaxis.

Toward a Novel Multilocus Phylogenetic Taxonomy for the Dermatophytes.

Type and reference strains of members of the onygenalean family Arthrodermataceae have been sequenced for rDNA ITS and partial LSU, the ribosomal 60S protein, and fragments of ß-tubulin and translation elongation factor 3. The resulting phylogenetic trees showed a large degree of correspondence, and topologies matched those of earlier published phylogenies demonstrating that the phylogenetic representation of dermatophytes and dermatophyte-like fungi has reached an acceptable level of stability. All trees showed Trichophyton to be polyphyletic. In the present paper, Trichophyton is restricted to mainly the derived clade, resulting in classification of nearly all anthropophilic dermatophytes in Trichophyton and Epidermophyton, along with some zoophilic species that regularly infect humans. Microsporum is restricted to some species around M. canis, while the geophilic species and zoophilic species that are more remote from the human sphere are divided over Arthroderma, Lophophyton and Nannizzia. A new genus Guarromyces is proposed for Keratinomyces ceretanicus. Thirteen new combinations are proposed; in an overview of all described species it is noted that the largest number of novelties was introduced during the decades 1920-1940, when morphological characters were used in addition to clinical features. Species are neo- or epi-typified where necessary, which was the case in Arthroderma curreyi, Epidermophyton floccosum, Lophophyton gallinae, Trichophyton equinum, T. mentagrophytes, T. quinckeanum, T. schoenleinii, T. soudanense, and T. verrucosum. In the newly proposed taxonomy, Trichophyton contains 16 species, Epidermophyton one species, Nannizzia 9 species, Microsporum 3 species, Lophophyton 1 species, Arthroderma 21 species and Ctenomyces 1 species, but more detailed studies remain needed to establish species borderlines. Each species now has a single valid name. Two new genera are introduced: Guarromyces and Paraphyton. The number of genera has increased, but species that are relevant to routine diagnostics now belong to smaller groups, which enhances their identification.

Arabidopsis chloroplast RNA binding proteins CP31A and CP29A associate with large transcript pools and confer cold stress tolerance by influencing multiple chloroplast RNA processing steps.

Chloroplast RNA metabolism is mediated by a multitude of nuclear encoded factors, many of which are highly specific for individual RNA processing events. In addition, a family of chloroplast ribonucleoproteins (cpRNPs) has been suspected to regulate larger sets of chloroplast transcripts. This together with their propensity for posttranslational modifications in response to external cues suggested a potential role of cpRNPs in the signal-dependent coregulation of chloroplast genes. We show here on a transcriptome-wide scale that the Arabidopsis thaliana cpRNPs CP31A and CP29A (for 31 kD and 29 kD chloroplast protein, respectively), associate with large, overlapping sets of chloroplast transcripts. We demonstrate that both proteins are essential for resistance of chloroplast development to cold stress. They are required to guarantee transcript stability of numerous mRNAs at low temperatures and under these conditions also support specific processing steps. Fine mapping of cpRNP-RNA interactions in vivo suggests multiple points of contact between these proteins and their RNA ligands. For CP31A, we demonstrate an essential function in stabilizing sense and antisense transcripts that span the border of the small single copy region and the inverted repeat of the chloroplast genome. CP31A associates with the common 3'-terminus of these RNAs and protects them against 3'-exonucleolytic activity.

The RNA-recognition motif in chloroplasts.

Chloroplast RNA metabolism is characterized by multiple RNA processing steps that require hundreds of RNA binding proteins. A growing number of RNA binding proteins have been shown to mediate specific RNA processing steps in the chloroplast, but little do we know about their regulatory importance or mode of molecular action. This review summarizes knowledge on chloroplast proteins that contain an RNA recognition motif, a classical RNA binding domain widespread in pro- and eukaryotes. Several members of this family respond to external and internal stimuli by changes in their expression levels and protein modification state. They therefore appear as ideal candidates for regulating chloroplast RNA processing under shifting environmental conditions.

Chloroplast ribonucleoprotein CP31A is required for editing and stability of specific chloroplast mRNAs.

Chloroplast ribonucleoproteins (cpRNPs) are nuclear-encoded, highly abundant, and light-regulated RNA binding proteins. They have been shown to be involved in chloroplast RNA processing and stabilization in vitro and are phylogenetically related to the well-described heterogeneous nuclear ribonucleoproteins (hnRNPs). cpRNPs have been found associated with mRNAs present in chloroplasts and have been regarded as nonspecific stabilizers of chloroplast transcripts. Here, we demonstrate that null mutants of the cpRNP family member CP31A exhibit highly specific and diverse defects in chloroplast RNA metabolism. First, analysis of cp31a and cp31a/cp31b double mutants uncovers that these 2 paralogous genes participate nonredundantly in a combinatorial fashion in processing a subset of chloroplast editing sites in vivo. Second, a genome-wide analysis of chloroplast transcript accumulation in cp31a mutants detected a virtually complete loss of the chloroplast ndhF mRNA and lesser reductions for specific other mRNAs. Fluorescence analyses show that the activity of the NADH dehydrogenase complex, which also includes the NdhF subunit, is defective in cp31a mutants. This indicates that cpRNPs are important in vivo for calibrating the expression levels of specific chloroplast mRNAs and impact chloroplast physiology. Taken together, the specificity and combinatorial aspects of cpRNP functions uncovered suggest that these chloroplast proteins are functional equivalents of nucleocytosolic hnRNPs.