5th World Workshop on Oral Health and Disease in AIDS

A21

The Frequencies and Biological Properties of Candida albicans and C. dubliniensis from HIV-Positive and -Negative Japanese

T Ohshima*, S Namikoshi, U Yasunari, H Watanabe, N Maeda.

Tomoko Ohshima Organisation, Tsurumi University, Japan

Tomoko Ohshima: oshima-t@tsurumi-u.ac.jp

Introduction: Candida dubliniensis, which was originally classified as C. albicans, has been implicated in candidasis in HIV/AIDS patients. However, there is little data on the prevalence of C. albicans and C. dubliniensis in HIV/AIDS patients in Japan.

Objectives: The aims of this study were to investigate the prevalence of C. dubliniensis and C. albicans in the Japanese and to compare the pathogenicity of these species in this population. 

Methods: A total of 581 strains were isolated from 65 HIV-positive patients and 1438 HIV-negative controls. They appeared as green colonies on CHROM agar. They were typed as C. albicans A, B or C, or C. dubliniensis genotype D using PCR. In addition growth on Sabouraud's Dextrose Agar at 300C and 420C, carbohydrate assimulation, secreted aspartic proteinases (SAP) production and antifungal sensitivity of C. albicans and C. dubliniensis was assessed. 

Results: More than half the isolates typed as A, 10% as B and 20% as genotype C. Genotype D was found in 10% of HIV-positive and HIV-negative subjects except in the Okinawa island area where this genotype formed between 30 to 50% of the strains isolated from HIV-negative subjects. These results showed that C. dubliniensis occurred in both HIV-positive and negative subjects, but varied from 0 to 50% dependent upon the region. The average growth rate of C. dubliniensis on Sabouraud's Dextrose Agar incubated at 30°C was low 0.5 (n=10) compared to C. albicans 0.96 (n=106). The carbohydrate assimilation tests showed no difference between the two species, although up to 75% of strains from HIV-negative subjects showed low levels of xylose assimilation. All strains of C. dubliniensis grew poorly at 42°C suggesting that growth at this temperature could be used to distinguish between the two species. Secreted aspartic proteinases (SAPs) production levels of C. dubliniensis was moderate (relative activity 0.20, n=40) but lower than C. albicans (0.25, n=117). Most C. albicans from HIV-positive patients produced low level of SAPs (0.21, n=6). Contrary to our expectation, susceptibility of C. dubliniensis to antifungal agents was higher than C. albicans (Fluconazole p<0.05; Miconazole p<0.001).  C albicans isolates from HIV-positive patients showed high susceptibility especially to the azoles (Fluconazole p<0.0001: Intraconazole p<0.01; Miconazole p<0.01) whereas C. dubliniensis susceptibility was low (Miconazole p<0.01) but not resistant.

Conclusion: C. dubliniensis was less pathogenic than C. albicans. However, C. dubliniensis derived from HIV-positive patients had lower susceptibility to azoles than isolates from HIV-negative subjects. If strains are isolated from HIV-positve patients with candidiasis, inducible resistance must be considered.