Seborrheic dermatitis flare in a Dutch male due to commensal Malassezia furfur overgrowth

Effects of Malassezia globosa on the Expression of Thymic Stromal Lymphopoietin and Differentiation of T Helper Cells in MC903-Induced Atopic Dermatitis Mouse Model

Atopic dermatitis (AD) is a chronic and inflammatory disease with an immunogenetic basis that can be triggered by extrinsic and intrinsic factors, including dysbiosis of the skin microbiota. The lipophilic Malassezia globosa is one of the dominant fungal species on the skin of AD patients. Malassezia and the host pathophysiologic mechanism underlying its role in exacerbating AD symptoms remain to be elucidated. This experiment established a fungal overgrowth model by topical administration suspension of M. globosa on BALB/c mice (M group) and MC903-induced AD model (AD+M group). Our results suggested that more severe AD-like lesions and higher dermatitis scoring were observed in the AD+M group compared with the AD group. The expression of TSLP mRNA in the tissue and serum IgE were highly increased in the AD group, while decreased significantly in the AD+M group. The expression levels of IL-17A and IL-22 in ear tissues and serum were significantly increased with M. globosa stimulation, especially in the AD+M group. Meanwhile, the percentage of Th17 and Th22 cells in the spleen were positively correlated with IL-17A and IL-22 levels in the serum. In contrast, IFN-γ and IL-4 production were significantly decreased in the AD+M group compared with the AD group. This study demonstrated that overgrowing M. globosa could aggravate AD symptoms and that IL-17A and IL-22 may be involved in the process. The promotion of IL-17A and IL-22 production induced by M. globosa may restrain the development of TSLP and inhibit the Th1/Th2 type skin inflammation.

Malassezia pachydermatis from brown bear: A comprehensive analysis reveals novel genotypes and distribution of all detected variants in domestic and wild animals

Malassezia pachydermatis (phylum Basidiomycota, class Malasseziomycetes) is a zoophilic opportunistic pathogen with recognized potential for invasive infections in humans. Although this pathogenic yeast is widespread in nature, it has been primarily studied in domestic animals, so available data on its genotypes in the wild are limited. In this study, 80 yeast isolates recovered from 42 brown bears (Ursus arctos) were identified as M. pachydermatis by a culture-based approach. MALDI-TOF mass spectrometry (MS) was used to endorse conventional identification. The majority of samples exhibited a high score fluctuation, with 42.5% of isolates generating the best scores in the range confident only for genus identification. However, the use of young biomass significantly improved the identification of M. pachydermatis at the species confidence level (98.8%). Importantly, the same MALDI-TOF MS efficiency would be achieved regardless of colony age if the cut-off value was lowered to ≥1.7. Genotyping of LSU, ITS1, CHS2, and β-tubulin markers identified four distinct genotypes in M. pachydermatis isolates. The most prevalent among them was the genotype previously found in dogs, indicating its transmission potential and adaptation to distantly related hosts. The other three genotypes are described for the first time in this study. However, only one of the genotypes consisted of all four loci with bear-specific sequences, indicating the formation of a strain specifically adapted to brown bears. Finally, we evaluated the specificity of the spectral profiles of the detected genotypes. MALDI-TOF MS exhibited great potential to detect subtle differences between all M. pachydermatis isolates and revealed distinct spectral profiles of bear-specific genotypes.

Translational medical mycology guides clinical and laboratory practice on fungal diseases

Patients with fungal infection having skin lesions may consult a dermatologist, which is a diagnostic and therapeutic challenge. Dermatologists take samples from the lesion to check the fungal elements under a microscope by KOH preparation and then treat the patient. This model has advanced from bedside to bench and from bench to bedside (B to B to B), which is defined as Translational Medical Mycology. Dermatologists have an advantageous position in finding, isolating and identifying the pathogenic fungi and treating the patient with antifungal drugs. Samples should be cultured in different media with or without chloramphenicol and cycloheximide and incubated at room temperature or 37 °C. Non-culture techniques such as polymerase chain reaction based molecular identification, transmission electron microscopy, scanning electron microscopy, biochemistry tests and histopathology are also necessary to confirm the identification of the species, especially when the routine culture is negative. We start treatment upon obtaining evidence of fungal infection, i.e., positive KOH examination. Antifungal drugs such as itraconazole, fluconazole, terbinafine and amphotericin B can be used alone or in combination based on the fungal species and the location of the lesion. Practice on fungal infection includes screening of the patient, merging all of the laboratory techniques and methods from the microbiologists, pathologists, molecular researchers, identification of the pathogen and determination of the optimum antifungal drug.

Genetic polymorphism of Malassezia furfur isolates from Han and Tibetan ethnic groups in China using DNA fingerprinting

Reported isolation rates of Malassezia yeast from human skin show geographic variations. In China, the populations of the Han (1,182.95 million) and Tibetan (5.41 million) ethnic groups are distributed over 9.6 and 3.27 million square kilometers respectively, making biodiversity research feasible and convenient. Malassezia furfur clinical strains (n = 29) isolated from different individuals, with or without associated dermatoses, of these two ethnic groups (15 Han and 12 Tibetan) were identified and analyzed with DNA fingerprinting using single primers specific to minisatellites. Using the Bionumerics software, we found that almost all M. furfur clinical isolates and type strains formed five distinct group clusters according to their associated skin diseases and the ethnic groups of the patients. These findings are the first to focus on the genetic diversity and relatedness of M. furfur in the Tibetan and Han ethnic groups in China and reveal genetic variation associated with related diseases, host ethnicity and geographic origin.

Clavispora lusitaniae and Chaetomium atrobrunneum as rare agents of cutaneous infection

We describe the first case of cutaneous infection caused by Chaetomium atrobrunneum and Clavispora lusitaniae in a one-and-a-half-year-old boy with acute and severe inflammation around his left eyelid. He presented to our outpatient center with a 6-day history and previously ineffective antibacterial therapy. Scanning electron microscopy (SEM) revealed hyphae and spores were on the surface of the crusty exudates and also penetrated into it, and the microbiology study further showed their characteristic cultural features. Fungal isolates were identified by the amplification and sequencing of the 26S RNA gene and of the ITS region, as C. lusitaniae and C. atrobrunneum. Up until now, most known clinical records of these rare species have shown them as agents of deep mycosis. Due to the emergency situation, medications were administered promptly and confirmed by subsequent fungal identification and successful therapeutic outcome. This article illustrates the importance of recognizing fungal infections, especially those caused by uncommon pathogens. Limitations in the routine identification procedures and therapeutic options of this emerging opportunistic agent are also discussed in this report.

Malassezia furfur fingerprints as possible markers for human phylogeography

Malassezia furfur was the first species described within the cosmopolitan yeast genus Malassezia, which now comprises 13 species. Reported isolation rates of these species from healthy and diseased human skin show geographic variations. PCR-fingerprinting with the wild-type phage M13 primer (5'-GAGGGTGGCGGTTCT-3') was applied to investigate phylogeographic associations of M. furfur strains isolated from Scandinavians residing permanently in Greece, in comparison to clinical isolates from Greek, Bulgarian and Chinese native residents. Seven M. furfur strains from Scandinavians were compared with the Neotype strain (CBS1878), CBS global collection strains (n=10) and clinical isolates from Greece (n=4), Bulgaria (n=15) and China (n=6). Scandinavian, Greek and Bulgarian M. furfur strains mostly formed distinct group clusters, providing initial evidence for an association with the host's geographical origin and with the underlying skin condition. These initial data address the hypothesis that M. furfur could be a eukaryotic candidate eligible for phylogeographic studies.