Detection of Candida dubliniensis in Oropharyngeal Samples from Human Immunodeficiency Virus-Infected Patients in North America by Primary CHROMagar Candida Screening and Susceptibility Testing of Isolates

Abstract

Candida dubliniensis has been associated with oropharyngeal candidiasis in patients infected with human immunodeficiency virus (HIV). C. dubliniensis isolates may have been improperly characterized as atypical Candida albicans due to the phenotypic similarity between the two species. Prospective screening of oral rinses from 63 HIV-infected patients detected atypical dark green isolates on CHROMagar Candida compared to typical C. albicans isolates, which are light green. Forty-eight atypical isolates and three control strains were characterized by germ tube formation, differential growth at 37, 42, and 45°C, identification by API 20C, fluorescence, chlamydoconidium production, and fingerprinting by Ca3 probe DNA hybridization patterns. All isolates were germ tube positive. Very poor or no growth occurred at 42°C with 22 of 51 isolates. All 22 poorly growing isolates at 42°C and one isolate with growth at 42°C showed weak hybridization of the Ca3 probe with genomic DNA, consistent with C. dubliniensis identification. No C. dubliniensisisolate but only 18 of 28 C. albicans isolates grew at 45°C. Other phenotypic or morphologic tests were less reliable in differentiating C. dubliniensis from C. albicans. Antifungal susceptibility testing showed fluconazole MICs ranging from ≤0.125 to 64 μg/ml. Two isolates were resistant to fluconazole (MIC, 64 μg/ml) and one strain was dose dependent susceptible (MIC, 16 μg/ml). MICs of other azoles, including voriconazole, itraconazole, and SCH 56592, for these isolates were lower. C. dubliniensis was identified in 11 of 63 (17%) serially evaluated patients. Variability in phenotypic characteristics dictates the use of molecular and biochemical techniques to identifyC. dubliniensis. This study identifies C. dubliniensis in HIV-infected patients from San Antonio, Tex., and shows that C. dubliniensis is frequently detected in those patients by using a primary CHROMagar screen.

Oropharyngeal carriage of Candida species in HIV‐infected patients in India

“…9 In 1995, Sullivan et al 10 recovered form AIDS patients a new species of Candida, namely, C. dubliniensis differing from C. albicans in certain phenotypic and molecular characteristics. Candida dubliniensis has been reported from oropharyngeal samples of patients with advanced AIDS having mean CD4 cell counts <50 mm 3,10,11 but this emerging yeast has not been reported hitherto from Indian patients.…”

Comparison of Candida dubliniensis and C. albicans based on polar lipid composition

“…Although the C. dubliniensis isolates examined did not assimilate a-methyl-D D-glucoside, xylose and DL DL-lactate such non-assimilation is again regarded as a typical property of C. dubliniensis (Gales et al 1999;Pincus et al 1999;Giammanco et al 2000) and the biocode obtained (vide supra) is typical of C. dubliniensis (Giammanco et al 2000;Sullivan et al 1997). In some studies, C. dubliniensis has been differentiated on CHROMagar Candida based on the production of dark green colonies compared with the lighter green colonies of C. albicans (Kirkpatrick et al 1998). However, others have not been able to differentiate C. dubliniensis from C. albicans isolates by the colour of colonies (Tintelnot et al 2000).…”

Candida albicans or Candida dubliniensis?

“…to grow at 45°C and Kirkpatrick et al [25] reported an even higher percentage of C. albicans isolates (36%) that failed to grow at this temperature. Pincus et al [20] stated that these variable results may be explained by poor temperature control in incubators or differences in media composition.…”

“…Similarly, Kurzai et al [18] found that characteristic chlamydospore formation on rice-Tween agar was only observed in 57% of C. dubliniensis isolates and concluded that this characteristic cannot be used for accurate identification of this species. In addition, Kirkpatrick et al [25] found that only 70% of the examined C. dubliniensis isolates produced abundant chlamydospores, while 4% of the C. albicans isolates also produced abundant chlamydospores on corn meal agar. This was confirmed by Á lvarez et al [17] who found that 13% of C. albicans isolates examined also produced abundant chlamydospores in pairs, triplets or clusters on corn meal-Tween agar.…”