Comparative analysis of genetic variability among Candida albicans isolates from different geographic locales by three genotypic methods

Abstract

The objective of the present study was to conduct a comparative genotypic analysis of Candida albicans isolates from the United States, Europe, and Southeast Asia to determine whether differences between isolates might be associated with geographic locations. The genotypes of 86 unrelated isolates of C. albicans (from the United States and Europe) and 26 isolates from Singapore were examined by three DNA typing methods. Computer-assisted methods were used to analyze the gel patterns for all isolates. A dendrogram based on the overall similarity of the patterns obtained by restriction endonuclease analysis (REA) with EcoRI clustered the U.S. and European isolates into two major groups (groups A and B). The Singaporean isolates demonstrated unique REA profiles, with nine isolates having both or neither of the REA-characteristic 3.7-and 4.2-kb bands present in groups A and B. By REA profiles, the Singaporean isolates were related to each other with similarity values (S AB s) of >0.80, but only one isolate mixed with the U.S. and European isolates at this S AB (an arbitrary threshold for genetic similarity). Randomly amplified polymorphic DNA (RAPD) analysis generated DNA profiles that clustered the C. albicans isolates into approximately the same number of distinct typing groups as REA. However, isolates identical to each other by REA were generally different from each other by RAPD analysis. In a composite dendrogram prepared from the results obtained by RAPD analysis, the isolates from the United States and Europe clustered in major groups with S AB s of >0.85, while Singaporean isolates connected to these clusters at S AB s of >0.75. Pulsed-field gel electrophoresis was less discriminatory, discerning about one-third as many distinct subtypes as REA or RAPD analysis; the Singaporean isolates were distributed randomly with the U.S. and European isolates. These results suggest that a high degree of genetic diversity exists between C. albicans isolates from Southeast Asia and those from the United States and Europe.

Investigation of the possible association between nosocomial candiduria and candidaemia

“…The blood and urine isolates of C. glabrata from one patient had identical profiles. In the present study, restriction endonuclease analysis was more discriminatory than RAPD, in accordance with previous findings [35,36]. Overall, among the 23 pairs of blood and urine isolates from 23 patients, the isolate in the blood was different from that in the urine for 52% of the patients.…”

Molecular epidemiology ofCandidaspecies isolated from clinical specimens of intensive care unit patients

“…Band patterns of two isolates can be transformed into numerical values such as similarity coefficients. Dice coefficient was the most frequently used one for Candida species in studies reporting similarity coefficients, 11,22,23,30,31 thus we used this coefficient as well. Soll 12 reminds us that no standard evaluation criteria have been validated for the RAPD-PCR test.…”

Molecular methods for strain typing of Candida albicans : a review

“…The performance of each typing technique should be assessed in terms of discriminatory power, reproducibility and ease of performance and interpretation. Discriminatory power refers to the ability of the technique to identify the same strain or highly related strains in independent isolates, to assess microevolution within the same strain, to group or cluster moderately related strains and to discriminate between unrelated strains (Clemons et al 1997;Chen et al 2005;Chowdhary et al 2006).…”

“…Currently, EK analysis is usually associated with other techniques, and it is shown to be the least discriminatory method when used for typing related isolates (Chen et al 2005;Ben Abdeljelil et al 2010. Nevertheless, the resolution power of EK analysis can be improved by the prior digestion of chromosome-length DNA with endonucleases before PFGE (Voss et al 1995;Clemons et al 1997;Shin et al 2004;Ben Abdeljelil et al 2012b).…”