Clade Related AmphotericinB Resistance Among South African Candida Albicans Isolates

OBJECTIVE: Oral candidiasis is the most commonly encountered oral manifestation in HIV/AIDS patients and Candida albicans the most frequently associated species. Recently DNA fingerprinting established 5 sub-types, or clades, with regional specificity, among clinical isolates of C. albicans. The SA clade predominated among isolates obtained from black, healthy individuals as well as HIV/AIDS patients. Antifungal resistance testing of South African oral yeast isolates revealed that 8.5% of isolates were resistant to amphotericin B. The purpose of this study was to determine whether the observed natural resistance among oral isolates of C. albicans was related to a particular clade.

METHODS: The broth microdilution technique as prescribed by the NCCLS, was employed for antifungal resistance testing of 589 oral yeast isolates. All of the C. albicans isolates exhibiting an inherent, or natural resistance to amphotericin B (MIC >1µg/ml) were DNA fingerprinted using the moderately repetitive Ca3 probe.

RESULTS: Of the 40 (8.4%) resistant C. albicans isolates, group SA constituted 74%, Group I 11% and groups II and NG (isolates not belonging to any particular group) 7,4% respectively.

CONCLUSION: This, as yet unknown, in vitro resistance could hold serious implications for the management of South African patients requiring treatment with amphotericin B for systemic C. albicans infections.