Rapid Differentiation of <b><i>Candida dubliniensis</i></b> from <b><i>Candida albicans</i></b> by Early <i>D</i>-Xylose Assimilation

Abstract

Objective: To determine if D-xylose (XYL) and/or α-methyl-D-glucoside (MDG) assimilation can be used reliably as a rapid test to differentiate Candida dubliniensis from Candida albicans at an earlier time point such as 2 h after inoculation. Materials and Methods: Thirty isolates of C. albicans and C. dubliniensis recovered from anatomical sites and clinical specimens were used. Isolates were inoculated into the API 20C AUX yeast identification system, and incubated at 30°C. XYL and MDG assimilations were read at 2-hour intervals beginning 2 h after the initial inoculation and up to 24 h of incubation; thereafter, results were read after 48 and 72 h. Results: Twenty-nine (97%) C. albicans isolates had assimilated XYL at 16 h and, by 24 h, all isolates were positive for XYL assimilation. None of the C. dubliniensis isolates assimilated XYL. The MDG assimilation revealed that 24, 40, 92 and 100% of C. albicans isolates became positive after 16, 24, 48 and 72 h of incubation, respectively, whereas only 3% of C. dubliniensis isolates assimilated MDG after 72 h. Conclusions: The findings showed that it is possible to rapidly differentiate C. albicans from C. dubliniensis isolates using the API 20C AUX carbohydrate assimilation kits after 16 h of incubation at 30°C based on the XYL assimilation.

A Combination Fluorescence Assay Demonstrates Increased Efflux Pump Activity as a Resistance Mechanism in Azole-Resistant Vaginal Candida albicans Isolates

“…For further identification, the strains were grown in YAD medium (1.7 g of yeast nitrogen base without amino acids and without ammonium sulfate, plus 5.0 g of ammonium sulfate per liter) with 5% xylose (32) to distinguish between C. albicans and Candida dubliniensis. C. albicans grows on YAD medium-xylose, while C. dubliniensis does not (33). Finally, the isolates that had reduced growth in the presence of xylose were verified to be C. albicans by PCR amplification of the cell wall protein-coding gene CRR.…”

Comparative Genome-Wide Characterization of Microsatellites in <b><i>Candida albicans</i></b> and <b><i>Candida dubliniensis</i></b> Leading to the Development of Species-Specific Marker

“…However, this, too, did not make any difference (Table 2). In transcript sequences, the maximum frequency of microsatellites was observed in Cd (4,587) compared with Ca (4,229). Similarly, the RD pattern of microsatellites in transcript sequences was higher in Cd, as in whole-genome sequence ( Table 2).…”

“…In 1995, a new species named Candida dubliniensis was identified among HIV-infected patients of Dublin, Ireland [3]. It showed similar phenotypic characteristics, commensalism, and opportunistic infection like C. albicans [4]. Moran et al [5] reported that these two species had about 96% similar gene sequences, and more than 60% are homologous.…”

“…Earlier in different confirmation studies, C. dubliniensis was incorrectly identified as C. albicans [11]. This suggests that conventional methods were non-reliable, mainly due to phenotypic similarities between them [4, 12]. Thus, various molecular methods were developed to differentiate among these two Candida species [13] to overcome such problems.…”