Electrophoretic karyotypes of clinically isolated yeasts of Candida albicans and C. glabrata

Abstract

One-hundred-and-four isolates of yeast were collected from the vaginas of !I7 outpatients. The isolates were identified by their characteristics in a carbohydrate assimilation test, a serological test and from their morphology.Cundida ufbicuns and Cmdida gfubrutu were the major isolates (75 % and 20 %, respectively). The karyotypes of the isolates were analysed by pulsed-field gel electrophoresis and almost all the karyotypes were distinguishable from one another when the band mobilities were carefully compared. Characteristics and karyotypes were not directly correlated, but seven C. ufbicms isolates (from six patients) had a common atypical karyotype and shared the same phenotype. These isolates are inferred to be generated by a wide genomic reorganization and mutation and the phenotypic changes may be advantageous for survival. The karyotypes of the isolates recovered from individual patients after intervals of 1-6 months were all identical except for one or two highly variable bands which were identified with an rDNA probe. This suggests that the variable bands are too variable to be useful for distinguishing strains, but from the patterns of the identical bands (i.e. except for the variable bands) we concluded that strains from individual patients do not change, at least over short periods. This, coupled with the extensive inter-isolate variability in karyotype, will be useful for Candida source determination and epidemiological studies.

The use of karyotyping in the systematics of yeasts

“…Medically important Candida species have been extensively studied (Asakura et al 1991;Iwaguchi et al 1990;Mahrous et al 1990;Rustchenko-Bulgac 1991;Snell & Wilkins 1986;Suzuki et al 1988). Chromosomal length polymorphisms have been observed in numerous species, and Rustchenko-Bulgac (1991) considers this phenomenon to be an important mechanism for increasing genetic variability of apomictic species.…”

Analysis of the cell cycle in the budding yeast Candida albicans by positioning of chromosomes by fluorescence in situ hybridization (FISH) with repetitive sequences

“…Plasmids pAT68 contained rDNA from Zygosaccharornyces bailli (Sugihara et al 1986) and its insert hybridized strongly with rDNA from C. albicans (Asakura et al 1991;Iwaguchi et al 1992b). pMMlO0 included a 23-bp telomere repeat sequences from C. albicans (Ca7 repeat) tandemly repeated over about 0.5 kbp (Sadhu ef al.…”

Extensive chromosome translocation in a clinical isolate showing the distinctive carbohydrate assimilation profile from a candidiasis patient

“…Such chromosome translocations may be a mechanism to confer phenotypic diversity on the imperfect fungus C. albicans. A clinical strain, TCH23, from a vaginal candidiasis patient shows distinct carbohydrate assimilation profile, serotype B, no chlamydospore formation and an atypical karyotype (Asakura et al, 1991). To examine the taxonomic relationship among C. albicans, Candida dubliniensis and this strain, we sequenced the internal transcribed spacer 1 (ITS1) of nuclear ribosomal DNA.…”

“…The karyotypes of clinical isolates of C. albicans are often distinguishable from one another (Lott et al, 1987;Magee and Magee, 1987;Merz et al, 1988;Iwaguchi et al, 1990;Asakura et al, 1991;Thrash-Bingham and Gorman, 1992;Doi et al, 1994). Thus, karyotype analysis is a powerful tool for precise identification in epidemiological studies in C. albicans.…”

“…Of 104 clinical isolates collected from 97 patients suffering from vaginal candidasis, seven shared a common phenotype: the same carbohydrate assimilation profile, no chlamydospores on cornmealTween 80 plates, serotype B by Candida Check, high extracellular proteinase activity and an atypical karyotype (Asakura et al, 1991). These strains lack the ability to assimilate adonitol, xylitol, a-methyl-D-glucoside, N-Acetyl-D-glucosamine and D-trehalose, all of which can be utilized in typical C. albicans strains.…”