BackgroundCandida glabrata follows C. albicans as the second or third most prevalent cause of candidemia worldwide. These two pathogenic yeasts are distantly related, C. glabrata being part of the Nakaseomyces, a group more closely related to Saccharomyces cerevisiae. Although C. glabrata was thought to be the only pathogenic Nakaseomyces, two new pathogens have recently been described within this group: C. nivariensis and C. bracarensis. To gain insight into the genomic changes underlying the emergence of virulence, we sequenced the genomes of these two, and three other non-pathogenic Nakaseomyces, and compared them to other sequenced yeasts.ResultsOur results indicate that the two new pathogens are more closely related to the non-pathogenic N. delphensis than to C. glabrata. We uncover duplications and accelerated evolution that specifically affected genes in the lineage preceding the group containing N. delphensis and the three pathogens, which may provide clues to the higher propensity of this group to infect humans. Finally, the number of Epa-like adhesins is specifically enriched in the pathogens, particularly in C. glabrata.ConclusionsRemarkably, some features thought to be the result of adaptation of C. glabrata to a pathogenic lifestyle, are present throughout the Nakaseomyces, indicating these are rather ancient adaptations to other environments. Phylogeny suggests that human pathogenesis evolved several times, independently within the clade. The expansion of the EPA gene family in pathogens establishes an evolutionary link between adhesion and virulence phenotypes. Our analyses thus shed light onto the relationships between virulence and the recent genomic changes that occurred within the Nakaseomyces.Sequence Accession NumbersNakaseomyces delphensis: CAPT01000001 to CAPT01000179Candida bracarensis: CAPU01000001 to CAPU01000251Candida nivariensis: CAPV01000001 to CAPV01000123Candida castellii: CAPW01000001 to CAPW01000101Nakaseomyces bacillisporus: CAPX01000001 to CAPX01000186

BackgroundMatrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI TOF-MS) allows the identification of most bacteria and an increasing number of fungi. The potential for the highest clinical benefit of such methods would be in severe acute infections that require prompt treatment adapted to the infecting species. Our objective was to determine whether yeasts could be identified directly from a positive blood culture, avoiding the 1–3 days subculture step currently required before any therapeutic adjustments can be made.Methodology/Principal FindingsUsing human blood spiked with Candida albicans to simulate blood cultures, we optimized protocols to obtain MALDI TOF-MS fingerprints where signals from blood proteins are reduced. Simulated cultures elaborated using a set of 12 strains belonging to 6 different species were then tested. Quantifiable spectral differences in the 5000–7400 Da mass range allowed to discriminate between these species and to build a reference database. The validation of the method and the statistical approach to spectral analysis were conducted using individual simulated blood cultures of 36 additional strains (six for each species). Correct identification of the species of these strains was obtained.Conclusions/SignificanceDirect MALDI TOF-MS analysis of aliquots from positive blood cultures allowed rapid and accurate identification of the main Candida species, thus obviating the need for sub-culturing on specific media. Subsequent to this proof-of-principle demonstration, the method can be extended to other clinically relevant yeast species, and applied to an adequate number of clinical samples in order to establish its potential to improve antimicrobial management of patients with fungemia.

Due to their ability to confer key functions of the native extracellular matrix (ECM), poly(ethylene glycol) (PEG)-based and PEG-modified materials have been extensively used as biocompatible and biofunctionalized substrate systems to study the influence of environmental parameters on cell adhesion in vitro. Given wide-ranging recent evidence that ECM compliance influences a variety of cell functions, detailed determination and characterization of the specific PEG surface characteristics including topography, stiffness and chemistry is required. Here, we studied two frequently used bio-active interfaces-PEG-based and PEG-modified surfaces-to elucidate the differences between the physical surface properties, which cells can sense and respond to. For this purpose, two sets of surfaces were synthesized: the first set consisted of nanopatterned glass surfaces containing cRGD-functionalized gold nanoparticles surrounded by a passivated PEG-silane layer and the second set consisted of PEG-diacrylate (PEG-DA) hydrogels decorated with cRGD-functionalized gold nanoparticles. Although the two sets of nanostructured materials compared here were highly similar in terms of density and geometrical distribution of the presented bio-ligands, as well as in terms of mechanical bulk properties, the topography and mechanical properties of the surfaces were found to be substantially different and are described in detail. In comparison to the very stiff and ultra-smooth surface properties of the PEG-passivated glasses, the mechanical properties of PEG-DA surfaces in the biologically relevant stiffness range, together with the increased surface roughness at micro-and nanoscale levels have the potential to affect cell behavior. This potential was verified by studying the adhesive behavior of hematopoietic KG-1a and rat embryonic fibroblast (REF52) cells on both surfaces.