Strain Typing and Determination of Population Structure ofCandida kruseiby Multilocus Sequence Typing

Abstract

A multilocus sequence typing (MLST) scheme for Candida krusei was devised, based on sequencing of six gene fragments of the species. The existence of heterozygous results for each of the six fragments sequenced confirms that C. krusei is diploid for at least part of its genome. The C. krusei MLST scheme had a discriminatory index of 0.998, making this system ideal for strain typing of C. krusei clinical isolates. MLST data for 122 independent C. krusei isolates from a range of geographical sources were analyzed by eBURST, structure, and the unweighted-pair group method using average linkages to derive a population structure comprising four subtype strain clusters. There was no evidence of geographical associations with particular subtypes. Data for pairs of isolates from seven patients showed that each patient was colonized and/or infected with strain types that were indistinguishable by MLST. The C. krusei MLST database can be accessed online at http://pubmlst.org/ckrusei/.

Multilocus Microsatellite Markers for Molecular Typing of Candida glabrata : Application to Analysis of Genetic Relationships between Bloodstream and Digestive System Isolates

“…During the last decade, molecular typing methods have significantly evolved, offering the possibility of sequence analysis. MLST has emerged as a highly reliable and discriminatory method both for tracing strains and for establishing population structure in a number of Candida species (e.g., C. albicans, C. tropicalis, C. parapsilosis, and C. krusei) (13,29,45,49). However, perhaps because of the highly clonal mode of reproduction of C. glabrata, MLST appears insufficient for tracing strains, despite allowing the definition of broad subpopulations (15, 31, 33).…”

Multilocus Sequence Typing Reveals that the Population Structure of Candida dubliniensis Is Significantly Less Divergent than That of Candida albicans

“…In the late 1990s, multilocus sequence typing (MLST), a technique based on the nucleotide sequence analysis of a set of housekeeping genes, was developed for the population analysis of several bacterial species (28). This technique has also been applied to the analysis of the diploid yeast C. albicans (9,10,54) and to other Candida species (17,25,53). In 2002, Bougnoux et al identified six housekeeping gene loci that allowed accurate and reproducible discrimination between unrelated C. albicans isolates (9).…”

Development of echinocandin resistance in Candida krusei isolates following exposure to micafungin and caspofungin in a BM transplant unit

“…7 Genotypes of the isolates were determined according to the multilocus sequence typing (MLST) method. 8 Antifungal susceptibility results (minimal inhibitory concentrations, MICs) and mutations for patients no. 2 and 3 are presented in Table 2.…”