Comparison of use of phenotypic and genotypic characteristics for identification of species of the anamorph genus Candida and related teleomorph yeast species

Abstract

A total of 49 type and neotype isolates and 32 clinical isolates of the anamorph genus Candida and related teleomorph genera were obtained from different culture collections and clinical laboratories. Isolates were subjected to two phenotypic methods of identification, Vitek yeast biochemical card (YBC) and API ID 32C, both based on carbohydrate assimilation, and one genotypic method, PCR fingerprinting, based on the detection of DNA polymorphisms between minisatellite-specific sequences with the primer M13 (5 GAGGG TGGCGGTTCT 3). The correct identification of a strain at the Centraalbureau voor Schimmelcultures was used as the gold standard for the identification of an isolate. When the study was restricted to species included in the respective biochemical databases, the Vitek YBC and API ID 32C systems performed adequately with positive identification rates of 87.3 and 76.8%, respectively. When uncommon species were added to the study, several of which are not included in the databases, the identification efficiencies were 76.5 and 77.5%, respectively. By comparison, all isolates were correctly identified by PCR fingerprinting, with 63 reference species profiles in the databank. Sufficient polymorphisms among the total set of banding patterns were observed, with adequate similarity in the major patterns obtained from a given species, to allow each isolate to be assigned unambiguously to a particular species. In addition, variations in minor bands allowed for differentiation to the strain level. PCR fingerprinting was found to be rapid, reproducible, and more cost-effective than either biochemical approach. Our results provide reference laboratories with an improved identification method for yeasts based on genotypic rather than phenotypic markers.

First isolation of Candida wangnamkhiaoensis from the blood of immunocompromised paediatric patient

“…Many variables including culture medium and the incubation temperature influenced the characteristics of both strains. 12,13 Conventional phenotypic methods although convenient to perform, was unable to identify the isolate. In this case study, the Vitek 2 system indicated the yeast isolate as C. famata.…”

PCR-Based Differentiation and Homology of Brewing and Type Strains of the Genus Saccharomyces

“…In this study fourteen research brewing yeast strains, three wild type S. cerevisiae isolates, one Polish production strain and three type strains were examined. 16,19,20) were isolated from two Polish breweries 4 and identified using…”

“…18) and the three isolates from the brewing industry (No. 16,19,20) gave identical patterns in each RFLP analyses and were grouped in OP IV. The OP IV group was different from the others using the HaeIII restriction profile.…”

“…Two other brewing strains S. carlsbergensis 37 and S. brasiliensis NCAIM 1223 demonstrated 97% and 78% homology respectively, while strains from brewing plants (No. 16,[18][19][20] established a separate branch with 60% homology to others. S. exiguus CBS 379 created an outgroup with 30% similarity.…”

“…Combinations of amplification of rDNA fragments and restriction analysis (RFLP-PCR rDNA) and /or randomly amplified polymorphic DNA (RAPD) have been studied 27,33 . RAPD alone has been applied to differentiate clinically important yeasts and food product isolates 16,24 .…”