Hugo Madrid

Sporothrix globosa, a pathogenic fungus with widespread geographical distribution.

Sporothrix globosa, reported from the USA, Europe, and Asia, is a recently described pathogenic species morphologically similar to Sporothrix schenckii. In this study, the phylogenetic affinities of 32 clinical and environmental isolates morphologically identified as S. schenckii, from Mexico, Guatemala, and Colombia, were assessed by cladistic analysis of partial sequences of the calmodulin gene using the maximum parsimony and neighbor-joining methods. The study revealed that one out of 25 isolates from Mexico (4%), one out of three isolates from Guatemala (33.3%), and two out of four isolates from Colombia (50%) belonged to S. globosa, while the other isolates belonged to S. schenckii sensu stricto. This is the first record of S. globosa from Mexico, and Central and South America.

Genotyping and in vitro antifungal susceptibility of Neoscytalidium dimidiatum isolates from different origins

This study evaluated the genetic variability and in vitro susceptibility patterns of isolates of Neoscytalidium dimidiatum and Scytalidium hyalinum from different geographical origins. Partial sequences of four loci (the ITS region and D1/D2 domains of the 28S rRNA gene and the tubulin and chitin synthase genes) were analysed. Among a total of 1970 bp sequenced in 24 isolates, 7 polymorphic positions (0.36%) were detected, representing five different sequence types (ST1-ST5), from which two (ST2 and ST3) were detected exclusively in isolates from plants, two (ST1 and ST5) were found only in clinical isolates and one (ST4) was observed in isolates from humans and from a mango tree. We propose subordinating S. hyalinum as a variety of N. dimidiatum. Amphotericin B was the most active drug, but low minimum inhibitory concentrations were also detected for voriconazole, terbinafine and anidulafungin.

Diversity of Bipolaris Species in Clinical Samples in the United States and Their Antifungal Susceptibility Profiles

ABSTRACT A set of 104 isolates from human clinical samples from the United States, morphologically compatible with Bipolaris, were morphologically and molecularly identified through the sequence analysis of the internal transcribed space (ITS) region of the nuclear ribosomal DNA (rDNA). The predominant species was Bipolaris spicifera (67.3%), followed by B. hawaiiensis (18.2%), B. cynodontis (8.6%), B. micropus (2.9%), B. australiensis (2%), and B. setariae (1%). Bipolaris cynodontis, B. micropus, and B. setariae represent new records from clinical samples. The most common anatomical sites where isolates were recovered were the nasal region (30.7%), skin (19.2%), lungs (14.4%), and eyes (12.5%). The antifungal susceptibilities of 5 species of Bipolaris to 9 drugs are provided. With the exception of fluconazole and flucytosine, the antifungals tested showed good activity.

In vitro antifungal susceptibility and molecular identity of 99 clinical isolates of the opportunistic fungal genus Curvularia

The in vitro antifungal susceptibility of a set of 99 clinical isolates of Curvularia was tested against 9 drugs using a reference microdilution method. The isolates had been identified previously to species level by comparing their ITS rDNA and glyceraldehyde-3-phosphate dehydrogenase gene sequences with those of reference strains. We were able to reliably identify 73.2% of the isolates, the most frequent species being Curvularia aeria, Curvularia geniculata/Curvularia senegalensis, Curvularia lunata, Curvularia inaequalis, Curvularia verruculosa, and Curvularia borreriae. Most of these isolates had been recovered from nasal sinus, which is generally considered one of the most frequent sites of infection by these fungi. In addition, at least 3 phylogenetic species that have not yet been formally described were detected. The most active drugs were the echinocandins, amphotericin B, and posaconazole, whereas voriconazole and itraconazole showed poor activity.

Sporothrix brunneoviolacea and Sporothrix dimorphospora, two new members of the Ophiostoma stenoceras-Sporothrix schenckii complex

Sporothrix inflata is a saprobic member of the Ophiostoma stenoceras-Sporothrix schenckii species complex, reported mainly from soil. Ophiostoma bragantinum, an ascomycete described from Brazil, has been proposed as its possible teleomorph. Previous studies revealed that Sporothrix inflata is phenotypically and genetically variable, suggesting the existence of cryptic species. During a continued survey on the biodiversity of microfungi from different countries, seven isolates morphologically similar to S. inflata were obtained from soil samples collected in Spain and USA. In this study their phenotypic features and phylogenetic relationships were assessed. DNA sequence data of two nuclear loci revealed that these isolates correspond to two unnamed clades in S. inflata s.l., one of which also included the type strain of Humicola dimorphospora, a species that traditionally has been considered a synonym of S. inflata. These two groups are proposed herein as Sporothrix brunneoviolacea sp. nov. and Sporothrix dimorphospora comb. nov. S. brunneoviolacea is characterized phenotypically by the production of a diffusible violet-brown pigment in culture and mostly globose, pigmented, lateral blastoconidia. On the other hand S. dimorphospora lacks diffusible pigments and shows mostly subglobose to obovoid pigmented lateral blastoconidia. In contrast to the type strain of S. inflata S. brunneoviolacea and S. dimorphospora assimilate raffinose. The phylogenetic analysis suggested that the proposed anamorph-teleomorph connection between S. inflata and O. bragantinum might not be correct.

Novel Curvularia species from clinical specimens

The fungal genus Curvularia includes numerous plant pathogens and some emerging opportunistic pathogens of humans. In a previous study we used morphology and sequences of the nuclear ribosomal internal transcribed spacer region (ITS) and the glyceraldehyde-3-phosphate dehydrogenase (gpd) gene to identify species within a set of 99 clinical Curvularia isolates from the USA. Seventy-two isolates could be identified while the remaining 27 isolates belonged in three unclassified clades that were tentatively labelled Curvularia sp. I, II and III. In the present study, we further assess the taxonomic placement of these isolates using sequences of ITS, gpd, the large subunit rDNA, and the second largest subunit of RNA polymerase II. DNA sequence comparisons with a set of 87 isolates representing 33 Curvularia spp. and members of the closely-related genera Bipolaris and Exserohilum revealed that Curvularia sp. I, II and III represent novel lineages in Curvularia. These lineages are morphologically different from the currently accepted species. In the phylogenetic tree, Curvularia sp. I and sp. III were each split into two distinct lineages. Morphology and phylogeny supported the proposal of five new species, to be named C. americana, C. chlamydospora, C. hominis, C. muehlenbeckiae and C. pseudolunata. The concatenated 4-locus phylogeny revealed the existence of six clades in Curvularia, which are associated with particular morphological features. They were named after representative species, namely americana, eragrostidis, hominis, lunata, spicifera and trifolii.

Johnalcornia gen. et. comb. nov., and nine new combinations in Curvularia based on molecular phylogenetic analysis

An examination of ex-type and authentic cultures of 34 species of Bipolaris and Curvularia by phylogenetic analysis of four loci (EF-1α, GAPDH, ITS and LSU) resulted in nine new combinations in Curvularia, as well as new synonymies for some species of Bipolaris and Curvularia. Lectotypes are designated for Bipolaris secalis and Curvularia richardiae, and an epitype is designated for Curvularia crustacea. A new monotypic genus, Johnalcornia, is introduced to accommodate Bipolaris aberrans, which clusters sister to the newly described Porocercospora. Johnalcornia differs morphologically from this taxon by producing distinctive conidia-like chlamydospores as well as comparatively thick-walled, geniculate conidiophores, with conidiogenous cells that have conspicuous scars. Johnalcornia further differs from related genera by forming the second conidial septum in the apical cell.

New species of Cordana and epitypification of the genus

Two interesting fungi belonging to the genus Cordana have been isolated recently in Spain from plant debris. Both are proposed here as new species, described and illustrated. Cordana mercadiana sp. nov. produces 0–1-septate conidia, with a prominent basal scar. Cordana verruculosa sp. nov. differs from the other species of the genus by its unique combination of aseptate, verruculose and small conidia. Both species are compared morphologically with other species of Cordana and their identities supported by the analysis of rDNA sequences. LSU sequence analysis revealed the congeneric relationship of Cordana and Pseudobotrytis; the members of both genera are in a well supported monophyletic lineage that appears to be related to the Coniochaetales but remains incertae sedis within the Sordariomycetes. To establish nomenclatural stability of the genus Cordana, an isolate of C. pauciseptata is designed here as epitype and the two species of Pseudobotrytis are transferred to Cordana. A dichotomous key is provided to identify the currently accepted species of Cordana.

Porocercospora seminalis gen. et comb. nov.,the causal organism of buffalograss false smut

False smut caused by Cercospora seminalis is an important disease of buffalograss (Buchloë dactyloides) affecting seed production. The pathogen prevents normal caryopsis development and causes considerable yield loss and reduced seed germination. The current taxonomic placement of the false-smut causal pathogen in the genus Cercospora is incorrect based on its morphological characteristics and DNA phylogeny. In the present study the phylogenetic position of C. seminalis is clarified based on DNA sequence analysis of three loci namely the internal transcribed spacer (ITS) region, partial nuclear ribosomal large subunit (LSU) and partial sequences of the RNA polymerase II second largest subunit (RPB2). A collection of C. seminalis isolates was made from buffalograss sites near Lincoln, Nebraska. DNA sequence data indicated that Cercospora seminalis is phylogenetically close to but distinct from species of Bipolaris and Curvularia (Pleosporaceae, Pleosporales). Cercospora seminalis morphologically had unique characteristics, namely densely aggregated and repeatedly branched conidiophores arising from a brown stroma, monotretic conidiogenous cells with inconspicuous loci, and scolecosporous conidia with distosepta, and thickened, darkened hila. Porocercospora is introduced as a new genus to accommodate the buffalograss false-smut pathogen.

Development of murine models of disseminated infection by Neoscytalidium dimidiatum

We have developed two murine models of disseminated infections by Neoscytalidium dimidiatum, an emerging dematiaceous fungus. Immunosuppressed mice were challenged through the lateral tail vein with 1 x 10(5) or 1 x 10(6) CFU/ml and immunocompetent animals with 1 x 10(6) or 1 x 10(7) CFU/ml. N. dimidiatum var. dimidiatum was more virulent than the nonpigmented variety, N. dimidiatum var. hyalinum. All mice infected with N. dimidiatum var. dimidiatum died within 8 days while those infected with N. dimidiatum var. hyalinum survived to the end of the experiment. Fungal load in tissue was also higher in animals inoculated with N. dimidiatum var. dimidiatum. In general, of the five organs tested, spleens and kidneys were most affected.