Polyphasic taxonomy ofAspergillus fumigatusand related species

Dermatitis caused by Neosartorya hiratsukae infection in a hedgehog

This case report describes the fungal dermatitis caused by Neosartorya hiratsukae infection in a household hedgehog confirmed by microscopic examination of conidiophores and DNA analyses including the internal transcribed spacer region, partial beta-tubulin, and the calmodulin gene. It is the first report of a natural N. hiratsukae infection in animals.

Aspergillus calidoustus sp. nov., causative agent of human infections previously assigned to Aspergillus ustus

Aspergillus ustus is a relatively rare human pathogen causing invasive infections in immunocompromised hosts. In this study isolates originating from clinical and other sources have been examined using molecular, morphological, and physiological approaches to clarify their species assignment. Phylogenetic analysis of partial beta-tubulin, calmodulin, actin, and intergenic transcribed spacer sequences indicated that none of the clinical isolates recognized previously as A. ustus belongs to this species. All but two of these isolates formed a well-defined clade related to A. pseudodeflectus based on sequence analysis of protein-coding regions. Morphological and physiological examination of these isolates indicated that they are able to grow above 37 degrees C, in contrast with A. ustus isolates, and give a positive Ehrlich reaction, in contrast with related species including A. granulosus, A. ustus, and A. pseudodeflectus. These isolates are proposed as a new species, A. calidoustus. Antifungal susceptibility testing showed that this species has decreased susceptibilities to several antifungal drugs. The triazoles are inactive in vitro, including the new azole posaconazole.

Sexual reproduction as the cause of heat resistance in the food spoilage fungus Byssochlamys spectabilis (anamorph Paecilomyces variotii)

Paecilomyces variotii is a common cosmopolitan species that is able to spoil various food- and feedstuffs and is frequently encountered in heat-treated products. However, isolates from heat-treated products rarely form ascospores. In this study we examined by using molecular techniques and mating tests whether this species can undergo a sexual cycle and form ascospores. The population structure of this species was examined by analyzing the nuclear ribosomal internal transcribed spacer 1 (ITS1) and ITS2 and the 5.8S rRNA gene, as well as partial beta-tubulin, actin, and calmodulin gene sequences. Phylogenetic analyses revealed that P. variotii is a highly variable species. Partition homogeneity tests revealed that P. variotii has a recombining population structure. In addition to sequence analyses, mating experiments indicated that P. variotii is able to form ascomata and ascospores in culture in a heterothallic manner. The distribution of MAT1-1 and MAT1-2 genes showed a 1:1 ratio in the progeny of the mating experiments. From the sequence analyses and mating data we conclude that P. variotii is the anamorph of Talaromyces spectabilis and that it has a biallelic heterothallic mating system. Since Paecilomyces sensu stricto anamorphs group within Byssochlamys, a new combination Byssochlamys spectabilis is proposed.

Characterization of a novel gene for strain typing reveals substructuring of Aspergillus fumigatus across North America

Fifty-five epidemiologically linked Aspergillus fumigatus isolates obtained from six nosocomial outbreaks of invasive aspergillosis were subtyped by sequencing the polymorphic region of the gene encoding a putative cell surface protein, Afu3g08990 (denoted as CSP). Comparative sequence analysis showed that genetic diversity was generated in the coding region of this gene by both tandem repeats and point mutations. Each unique sequence in an outbreak cluster was assigned an arbitrary number or CSP sequence type. The CSP typing method was able to identify "clonal" and genotypically distinct A. fumigatus isolates, and the results of this method were concordant with those of another discriminatory genotyping technique, the Afut1 restriction fragment length polymorphism typing method. The novel single-locus sequence typing (CSP typing) strategy appears to be a simple, rapid, discriminatory tool that can be readily shared across laboratories. In addition, we found that A. fumigatus isolates substructured into multiple clades; interestingly, one clade consisted of isolates predominantly representing invasive clinical isolates recovered from cardiac transplant patients from two different outbreak situations. We also found that the A. fumigatus isolate Af293, whose genome has been sequenced, possesses a CSP gene structure that is substantially different from those of the other A. fumigatus strains studied here, highlighting the need for further taxonomic study.

Molecular Phylogenetics of Multiple Genes on Aspergillus Section Fumigati Isolated from Clinical Specimens in Japan

A phylogenetic study based on sequence analysis of the beta-tubulin, hydrophobin and calmodulin genes was performed in 19 strains of Aspergillus fumigatus and related species isolated from clinical specimens in Japan. Correlations between detailed morphology and phylogeny were examined. Species in the section Fumigati were divided into five clades: clade I, typical strains of A. fumigatus; clade II, species including A. lentulus and A. fumisynnematus; clade III, species including A. fumigatiaffinis and A. novofumigatus, clade IV, atypical strains of A. fumigatus including A. viridinutans; and clade V, species including A. brevipes, A. duricaulis and A. unilateralis. Most of the examined strains from clinical specimens in Japan clustered together in clade I and exhibit globose conidia with lobate-reticulate ornamentation. Other strains from clinical specimens were divided into two clades (clades II and IV). The strains in clades II and the six strains in clade IV exhibit conidia with microtuberculate ornamentation, while A. viridinutans-complex in clades IV and the strains in clade V have conidia with lobate-reticulate ornamentation. The six strains are clearly distinguished from A. viridinutans-complex and are considered to be related to Neosartorya udagawae. The maximal growth temperatures of clades I, II, IV and V were above 50 degrees C, 45 degrees C, 42 degrees C and 42 degrees C, respectively. These data are useful for classification of species within the Aspergillus section Fumigati.