F. Javier Cabañes

Taxonomy and significance of black aspergilli.

Members of Aspergillus section Nigri (formerly A. niger group) are distributed worldwide and are regarded as common food spoilage fungi. Some of them are widely used and studied for industrial purposes. They are common sources of extracellular enzymes and organic acids to be used in food processing and are also used in the production of traditional foods, especially in the Orient. Products produced by strains of Aspergillus niger hold the GRAS (Generally Recognised As Safe) status from the FDA. However some species in Aspergillus section Nigri can produce ochratoxin A, a nephrotoxic mycotoxin. In spite of their industrial importance, the taxonomy of black aspergilli (Aspergillus section Nigri) is not clear and many attempts have been made in order to find suitable taxonomic criteria. The aim of this paper is to provide an overview of the significance of black aspergilli focusing on all the approaches made in the taxonomy of this group of fungi. Some species, such as A. carbonarius and uniseriate species can be easily recognised. In the A. niger aggregate, although speciation at molecular level has been proposed, no morphological differences can be observed and species identification will therefore remain problematic. Phylogenetic analyses of ITS and 5.8S rDNA gene region of representative black Aspergillus species and a simple key to the most common species that can be easily distinguished by morphological criteria are also included.

Malassezia Yeasts: How Many Species Infect Humans and Animals?

Malassezia species are lipophilic yeasts that are members of the normal mycobiota of the skin and mucosal sites of a variety of homeothermic animals. They are also among the few basidiomycetous fungi, such as some Cryptococcus spp., Rhodotorula spp., and Trichosporon spp., that can produce disease in man and animals. However, in contrast with these other species, which are quite often involved in disseminated infections in immunosuppressed patients, Malassezia yeasts are associated mainly with certain skin diseases [1]. This special lipophilic group of yeasts is unique among the fungi. Phylogenetically, they form a well-defined cluster of skinliving yeasts, surrounded by plant pathogens and phylloplaneinhabiting fungi (e.g., Ustilago, Tilletiopsis). However, the taxonomic position of the genus Malassezia in the classes of the phylum Basidiomycota is not yet totally well defined. Moreover, the sexual form of these yeasts is still unknown. Recently, a region corresponding to the mating type locus (MAT) has been identified for these yeasts, and it has been suggested that if there is an extant sexual cycle for some of these yeasts that it is more likely to be bipolar, with just two mating types, rather than tetrapolar, with many mating types [2]. In the last higher-level fungal phylogenetic classification revision [3], the monophyletic genus Malassezia was the only genus included in the order Malasseziales, which has an uncertain taxonomic position in the subphylum Ustilagomycotina (e.g., smut fungi). Very recently, the class Malasseziomycetes has been proposed to accommodate these fungi (2013, provided from an anonymous reviewer; unreferenced). They are taxonomically distant to the orders which include the other commented pathogenic basidiomycetous yeasts of the genera Cryptococcus (Filobasidiales) and Trichosporon in Agaricomycotina (e.g., mushrooms) and of the polyphyletic genus Rhodotorula (Sporidiobolales and Cystobasidiales) in Pucciniomycotina (e.g., rust fungi).

Biofilm development by clinical isolates of Malassezia pachydermatis.

Malassezia pachydermatis fungemia has been reported in patients receiving parenteral nutrition. Biofilm formation on catheters may be related to the pathogenesis of this mycosis. We investigated the biofilm-forming ability of 12 M. pachydermatis strains using a metabolic activity plate-based model and electronic microscopic evaluation of catheter surfaces. All M. pachydermatis strains developed biofilms but biofilm formation showed variability among the different strains unrelated to their clinical origin. This study demonstrates the ability of M. pachydermatis to adhere to and form biofilms on the surfaces of different materials, such as polystyrene and polyurethane.

Criptococosis y animales de compañía

This paper is a review of cryptococcosis in domestic animals. Cryptococcosis is an uncommon mycosis in domestic animals and its occurrence is sporadic. The disease is caused by Cryptococcus neoformans, although Cryptococcus gattii has been also isolated from different animal species. Although cryptococcosis has been reported in several animal species, the most frequently affected domestic animal is the cat. The present paper deals with feline and canine cryptococcosis, its common clinical signs and the different clinical forms of the disease in these species. The diagnosis and treatment of cryptococcosis is also discussed. Diagnosis usually includes cytologic examination, capsular antigen detection and culture and identification of the Cryptococcus species. The management of criptococcosis will review the most common therapeutic agents and their role in therapy. Finally, we will address the situation of cryptococcosis in domestic animals in Spain and the role of cryptococcosis as a zoonotic disease and its public health importance.

Importance of Resolving Fungal Nomenclature: the Case of Multiple Pathogenic Species in the Cryptococcus Genus

Cryptococcosis is a major fungal disease caused by members of the Cryptococcus gattii and Cryptococcus neoformans species complexes. After more than 15 years of molecular genetic and phenotypic studies and much debate, a proposal for a taxonomic revision was made. ABSTRACT Cryptococcosis is a major fungal disease caused by members of the Cryptococcus gattii and Cryptococcus neoformans species complexes. After more than 15 years of molecular genetic and phenotypic studies and much debate, a proposal for a taxonomic revision was made. The two varieties within C. neoformans were raised to species level, and the same was done for five genotypes within C. gattii. In a recent perspective (K. J. Kwon-Chung et al., mSphere 2:e00357-16, 2017, https://doi.org/10.1128/mSphere.00357-16 ), it was argued that this taxonomic proposal was premature and without consensus in the community. Although the authors of the perspective recognized the existence of genetic diversity, they preferred the use of the informal nomenclature “C. neoformans species complex” and “C. gattii species complex.” Here we highlight the advantage of recognizing these seven species, as ignoring these species will impede deciphering further biologically and clinically relevant differences between them, which may in turn delay future clinical advances.

Phylogenetic relationships of Malassezia species based on multilocus sequence analysis

Members of the genus Malassezia are lipophilic basidiomycetous yeasts, which are part of the normal cutaneous microbiota of humans and other warm-blooded animals. Currently, this genus consists of 14 species that have been characterized by phenetic and molecular methods. Although several molecular methods have been used to identify and/or differentiate Malassezia species, the sequencing of the rRNA genes and the chitin synthase-2 gene (CHS2) are the most widely employed. There is little information about the β-tubulin gene in the genus Malassezia, a gene has been used for the analysis of complex species groups. The aim of the present study was to sequence a fragment of the β-tubulin gene of Malassezia species and analyze their phylogenetic relationship using a multilocus sequence approach based on two rRNA genes (ITS including 5.8S rRNA and D1/D2 region of 26S rRNA) together with two protein encoding genes (CHS2 and β-tubulin). The phylogenetic study of the partial β-tubulin gene sequences indicated that this molecular marker can be used to assess diversity and identify new species. The multilocus sequence analysis of the four loci provides robust support to delineate species at the terminal nodes and could help to estimate divergence times for the origin and diversification of Malassezia species.

Chrysosporium-related fungi and reptiles: a fatal attraction.

1 Veterinary Mycology Group, Department of Animal Health and Anatomy, Veterinary School, Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain, 2 Department of Pathology, University of Texas Health Science Center, San Antonio, Texas, United States of America, 3 Mycology Unit, School of Medicine and Health Sciences, Institut d’Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Reus, Catalonia, Spain

Malassezia Yeasts in Animal Disease

During the last 20 years, interest in the genus Malassezia has increased dramatically among veterinarians. M. pachydermatis is now recognised as an important cause of dermatitis and otitis externa in dogs, but appears to be a relatively uncommon pathogen in other animal hosts. Cases of dermatitis or otitis externa in dogs and cats are normally managed by topical or systemic antifungal therapy and by correcting factors predisposing to infection. Lipid-dependent Malassezia are more frequently isolated in horses and domestic ruminants. This chapter reviews current knowledge on colonisation and infection of dogs, cats and other animals by Malassezia spp., including pathogenesis, clinical signs, diagnosis and treatment. The potential for zoonotic transfer of Malassezia spp. from animals to humans is also discussed.

Utility of Microsatellite Markers and Amplified Fragment Length Polymorphism in the Study of Potentially Ochratoxigenic Black Aspergilli

Microsatellite markers and the results of amplified fragment length polymorphism (AFLP) were compared in the characterization of 68 Aspergillus carbonarius and A. niger aggregate strains of differing ochratoxin-producing ability and from different geographic areas, isolated mainly from grapes and soil. AFLP was applied to both A. carbonarius and A. niger aggregate strains, and it clearly differentiated these species. Microsatellite markers were only applied to A. niger aggregate strains because of the species-specific nature of these markers. Both AFLP and microsatellite marker analyses were able to divide A. niger aggregate strains into the two recognized internal transcribed spacer (ITS)-5.8S rDNA RFLP types, N and T. Clustering of A. niger aggregate strains was similar in both AFLP and microsatellite analyses, yielding an additional separation of N type strains into two groups. Both microsatellite marker and AFLP analyses showed high levels of polymorphism in the A. niger aggregate (index of discriminatory power 0.991 and 1.0, respectively). Of the two techniques, microsatellite marker analysis was quicker and more straightforward to perform. In addition, microsatellite marker analysis is more reproducible, and the results can be expressed as quantitative data, making microsatellite markers a good candidate for use in large-scale studies of genetic diversity in A. niger aggregate species.

Thiabendazole resistance and mutations in the β‐tubulin gene of Penicillium expansum strains isolated from apples and pears with blue mold decay

Penicillium expansum is the causal agent of blue mold rot, a postharvest decay of stored fruits. This fungus also produces the mycotoxins patulin and citrinin. Control of P. expansum still relies mainly on the use of fungicides such as thiabendazole. Since its introduction, resistant strains have been reported. The aim of this work was to investigate the thiabendazole resistance and mutations in the beta-tubulin gene of P. expansum strains isolated from apples and pears with blue mold decay from Spain. A total of 71 strains of P. expansum were scored for resistance to thiabendazole and the beta-tubulin gene was sequenced. Out of 71 strains, 37 were sensitive and 34 were resistant to thiabendazole. Regarding the beta-tubulin gene sequence, 10 different genetic types were determined, with a 99.7-100% similarity. When the amino acid sequence was deduced, five different amino acid sequences were found. All except one of the sensitive strains lacked mutations in the region sequenced. Of the 34 resistant strains, only eight had mutations that involved the residues 198 and 240. All the strains with mutations at position 198 always corresponded to resistant isolates. However, a high percentage of resistant strains had no mutations in the region of the beta-tubulin gene sequenced, and so other mechanisms may be involved in thiabendazole resistance.