Molecular characterization of new clinical isolates of Candida albicans and C-dubliniensis in Japan: Analysis reveals a new genotype of C-albicans with group I intron

The genetic diversity of recent clinical isolates of Candida albicans in Ja pan was studied on the basis of amplified DNA band lengths determined with a specific PCR primer reported to have been designed to span a transposable intron region in the 25S rRNA gene. Our analyses of 301 clinical isolates of C. albicans showed that they could be classified into five genotypes: ge notype A (172 isolates), genotype B (66 isolates), genotype C (56 isolates) , genotype D (C dubliniensis; 5 isolates), and a new genotype (designated g enotype E; 2 isolates). The new genotype E was characterized to have a grou p I intron-like sequence, which is longer than hitherto reported ones and w hich has a nucleotide sequence length of 962 bp. Our analysis of the 962-bp sequence indicated that it is composed of an intron similar to that of C. dubliniensis of 621 bp with a 341-bp insertion. Analysis of the sequence of the internal transcribed spacer (ITS) region of the genotype E strain show ed that its sequence is identical to those of strains of other genotypes, w ith only a few base substitution differences. Throughout the study, the pos sible horizontal transfer of the group I intron between C. dubliniensis and C. albicans was suggested. A high degree of correlation between the presen ce of a group I intron in C. albicans genotype E and susceptibility to the antifungal agent flucytosine was observed. The five isolates of C dublinien sis examined in the present study showed genetic diversity when they were c ompared by randomly amplified polymorphic DNA fingerprinting pattern analys is, and this diversity was also confirmed by the analysis of ITS region seq uences.