Genotyping of Candida parapsilosis from three neonatal intensive care units (NICUs) using a panel of five multilocus microsatellite markers: broad genetic diversity and a cluster of related strains in one NICU.

Candida parapsilosis (CP) (n = 40) isolated from an unselected patient population in the neonatal intensive care units (NICUs) of three US hospitals were collected over periods of 3.5-9 years. Two previously published microsatellite markers and three additional trinucleotide markers were used to produce multiplex genotypes, which revealed broad strain diversity among the NICU isolates with a combined index of discrimination (D) = 0.

Bloodstream and non-invasive isolates of Candida glabrata have similar population structures and fluconazole susceptibilities.

We have compared multilocus sequence typing (MLST) and fluconazole susceptibility profiles of Candida glabrata bloodstream isolates obtained during active, population-based surveillance to those obtained from non-sterile sites of individuals with no evidence of fungal disease (i.e., non-invasive isolates) in the same US city during an overlapping time period.

Candidemia surveillance in Brazil: evidence for a geographical boundary defining an area exhibiting an abatement of infections by Candida albicans group 2 strains.

Prospective population surveillance has been conducted for candidemia in Brazil (A. L. Colombo, M.

Multicenter collaborative study for standardization of Candida albicans genotyping using a polymorphic microsatellite marker.

Microsatellite-based genotyping for Candida albicans can give discrepant results between laboratories when expressed in fragment sizes, because their determination depends on electrophoretic conditions. The interlaboratory reproducibility was assessed in six laboratories provided with an allelic ladder. Despite variations in size determinations, alleles were correctly assigned, making data transportable between laboratories.

Multilocus sequence type analysis reveals both clonality and recombination in populations of Candida glabrata bloodstream isolates from U.S. surveillance studies.

The human commensal yeast Candida glabrata is becoming increasingly important as an agent of nosocomial bloodstream infection. However, relatively little is known concerning the genetics and population structure of this species. We have analyzed 230 incident bloodstream isolates from previous and current population-based surveillance studies by using multilocus sequence typing (MLST).

Multilocus sequence typing of sequential Candida albicans isolates from patients with persistent or recurrent fungemia.

Multilocus sequence typing (MLST) is a useful tool to explore the phylogenetics and epidemiology of Candida albicans isolates recovered from cases of invasive candidiasis. The goal of this study was to determine whether the same or different strains were responsible for persistent or recurrent fungemia through the use of MLST and ABC typing on sequential C. albicans isolates from the same patient.

Development of a MLST-biased SNP microarray for Candida albicans.

We have developed a single nucleotide polymorphism (SNP) detection microarray for the human pathogenic yeast, Candida albicans, consisting of synthetic oligonucleotides bound to microscope slides. The array consists of multiple replicates of 79 SNPs, derived from 19 discrete loci located on all eight chromosomes. These loci include seven genes consisting of 57 SNPs that comprise a multi-locus sequence typing (MLST) consensus scheme for the species.

Evidence for a pseudo-outbreak of Candida guilliermondii fungemia in a university hospital in Brazil.

Fungal infections due to Candida species represent an important cause of nosocomial bloodstream infections. We report a large pseudo-outbreak of Candida guilliermondii fungemia that occurred in a university hospital in Brazil. C.

Molecular genotyping of Candida parapsilosis group I clinical isolates by analysis of polymorphic microsatellite markers.

Candida parapsilosis, a pathogenic yeast, is composed of three newly designated genomic species that are physiologically and morphologically indistinguishable. Nosocomial infections caused by group I C. parapsilosis are often associated with the breakdown of infection control practices and the contamination of medical devices, solutions, and indwelling catheters.

Assessment of ribosomal large-subunit D1-D2, internal transcribed spacer 1, and internal transcribed spacer 2 regions as targets for molecular identification of medically important Aspergillus species.

Molecular approaches are now being developed to provide a more rapid and objective identification of fungi compared to traditional phenotypic methods. Ribosomal targets, especially the large-subunit RNA gene (D1-D2 region) and internal transcribed spacers 1 and 2 (ITS1 and ITS2 regions), have shown particular promise for the molecular identification of some fungi. We therefore conducted an assessment of these regions for the identification of 13 medically important Aspergillus species: Aspergillus candidus, Aspergillus (Eurotium) chevalieri, Aspergillus (Fennellia) flavipes, Aspergillus flavus, Aspergillus fumigatus, Aspergillus granulosus, Aspergillus (Emericella) nidulans, Aspergillus niger, Aspergillus restrictus, Aspergillus sydowii, Aspergillus terreus, Aspergillus ustus, and Aspergillus versicolor.

The human commensal yeast, Candida albicans, has an ancient origin.

Candida albicans, the primary causative agent of candidiasis, is a ubiquitous member of the human flora and is capable of causing severe invasive disease. Despite its importance as a human pathogen, little is known concerning those factors creating and maintaining genetic diversity within the species and how extant strains reflect their evolutionary history. Based on nucleotide polymorphism frequencies, we estimated the time to a most recent common ancestor for the species to be about 3-16 million years, with variation due to molecular clock calibration.

Evidence for aneuploidy and recombination in the human commensal yeast Candida parapsilosis.

Isolates of Candida parapsilosis, including representatives of the three major sub-species groups, were screened for single nucleotide polymorphisms (SNPs) by sequencing five independent loci totaling 4kb per isolate. Group I isolates were highly conserved and in some cases, group I alleles were found in group II and III strains. Unique alleles were also associated with groups II and III, consistent with earlier observations of intergroup divergence.

Population structure of Candida albicans, a member of the human flora, as determined by microsatellite loci.

This study examines the macrogeographic population structure of Candida albicans, a yeast commensal of humans, through a population genetic analysis of 5 microsatellite loci in 13 cities. The populations were predominantly clonal with some recombination. About 5% of the genetic variation is between populations and the overall pattern is one of intermediate differentiation.

Stability of allelic frequencies and distributions of Candida albicans microsatellite loci from U.S. population-based surveillance isolates.

Allelic distributions and frequencies of five Candida albicans microsatellite loci have been determined for strains isolated from the bloodstream and obtained through active population-based surveillance in two U.S. metropolitan areas between 1998 and 2000.

Evidence for a more recently evolved clade within a Candida albicans North American population.

Candida albicans is diploid and displays a primarily clonal mode of reproduction. There is, however, evidence for meiosis and the degree to which this occurs in nature is unknown. Although random mating would act to obscure clonal lineages, previous studies have demonstrated that collections of North American isolates display three major partitions with no evidence of geographic clustering.

Towards understanding the evolution of the human commensal yeast Candida albicans.

Allelic frequencies and relationships for one dimorphic locus and three unlinked polymorphic loci have been determined for 114 unrelated isolates of Candida albicans, including 14 laboratory reference strains and 50 strains from each of two geographic regions. Although there was no indication of geographical partitioning, there were significant correlations for specific allelic pairs among loci and little evidence that any alleles were in Hardy-Weinberg equilibrium. This gives additional support for the concept that the primary mode of genetic inheritance in this species is clonal, with other intracellular genetic events playing a lesser role in the creation of genomic diversity.