Isolation of Candida dubliniensis from the Oral Cavity of an HIV-positive Child in Brazil

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Candida dubliniensis is a newly-recognized Candida species and an important infectious pathogen, particularly for HIV-positive patients. From oral smear samples from the radix linguae of 173 HIV-positive children, we obtained four yeast isolates which took a blue-green color on CHROMagar Candida plate at 37°C for 48 hours from one HIV-positive 3-year-old boy in Brazil. The isolates were difficult to grow on potato dextrose agar plate at 42°C, produced abundant chlamydospores on a cornmeal agar plate with Tween 80, and sprouted germ tubes in saline with horse serum, and the antigenic profile by CANDIDA CHECK test was useless. Carbohydrate assimilation tests by ID32C showed no reference code number in the reference book. The isolates were subjected to molecular biological assay of the DNA sequence of the large-subunit ribosomal DNA region (D1/D2) and randomly amplified polymorphic DNA (RAPD). The DNA sequence agreed with those of standard C. dubliniensis strains, and therefore, the isolates were identified as C. dubliniensis. RAPD band pattern analysis indicated that the clinical isolates might summarize one genotype. Although the child did not present oral lesions, the fungus might be latent for opportunistic infection.