Background: We conducted a study to determine the prevalence of vaginal colonization and infection with Candida albicans in HIV-infected women from Brazil and the susceptibility of these strains to amphotericin B and azole drugs. Expression of the MDR1, CDR1 and ERG11 genes conferring azole resistance was also evaluated. Methods: The vaginal samples were plated on CHROMagar Candida and identified by standard morphologic and biochemical characteristics. Broth microdilution MICs were determined as specified by the National Committee for Clinical Laboratory Standards document M27-A. Total RNA fro selected strain was isolated and used in northern blot analyses. Results: Among 127 HIV-infected women randomly enrolled in this study, positive cultures were obtained from 31 (81%) women with Candida vulvovaginitis and from 41 (46%) of asymptomatic women. 14 isolates with susceptibility dose-dependant resistance to azole drugs were found, five of these being Candida albicans strains. Overall, 4% of 57 C. albicans strains tested were resistant to azoles: one isolate with MIC 64 µg mL -1 for fluconazole and another one with MIC 1 µg mL -1 for ketoconazole. The CD4+ count below 200 cells mm -3 was closely related to colonization, symptoms of candidiasis due to C. albicans and reduced susceptibility to azole drugs, however this trend was not observed among the patients in use of highly active antiretroviral therapy (HAART). The C. albicans fluconazole resistant strain was found to have increased expression of CDR1 as determined by the northern blot. Conclusions: We found a relatively low rate of azole resistance on C. albicans isolates in this population of HIV-infected women. This may be due to the decreasing rates of mucosal candidiasis associated with HAART. For the C. albicans strain that was resistant to fluconazole, reduced intracellular accumulation of the drug appears to be a more important fluconazole resistance mechanism than alteration in the ergosterol biosynthetic pathway.
Full conference title:
The 15 th Congress of the International Society for Human and Animal Mycology
- ISHAM 15th (2003)