Management of Azole-Refractory Candida Species Using Boric Acid Preparations: A Case Study in Dar Es Salaam, Tanzania

Abstract

The aim of this study was to determine the antifungal agents and boric acid susceptibility to the azole-resistant Candida species, as well as clinical outcomes following treatment with antifungal agents that are commonly prescribed in Dar es Salaam and boric acid which is not available in Tanzania market. Microscopic examination of the vaginal discharge during prolonged therapy with three antifungal agents (clotrimazole, miconazole, and nystatin) and boric acid were carried out. Samples were collected from 150 women of reproductive age group (13 to 45 years) with chronic vaginal candidal infections. The samples were cultured in Sabouraud’s dextrose agar (supplemented with 0.005% chloramphenicol and 0.05% cycloheximide) followed by aerobic incubation for 48 hours at 37ºC in order to obtain pure cultures. Identification was done by Gram stain, while the test for ability to ferment and assimilate different sugars was done on API Candida and API 20C AUX. The stock cultures of Candida albicans (ATCC 32354), Candida glabrata (ATCC2001) and Candida guilliermondii (ATCC6260) were used as controls. Patients were dispensed together with 10 ml syringes for self douching of boric acid solution, and three commonly used antifungal vaginal drugs for Candida vaginitis. The results revealed a total of 167 Candida species dominated by C. albicans 116 (69.46%), followed by C. glabrata 21 (12.57%), C. krusei 8 (4.8%), C. tropicalis 7 (4.2%), C. famata 6 (3.59%), C. lusitaniae 5 (3.0%), C. parapsilosis, Trichosporon 2 (1.2%) and C. guilliermondii 1(0.6%). The results further showed that out of 116 C. albicans isolates, 23 (19.83%) were resistant to clotrimazole while 14 (12.1%) were resistant to miconazole in vitro test. Interestingly, all C. albicans isolates and the nonalbicans candida species were very sensitive to boric acid at a very low MIC values (0.025μg/ml). Generally, the overall success rate for clotrimazole in treating C. albicans infections was 41.7%, miconazole 56.5%, nystatin 77.3% and boric acid 100%. This study shows that, compared to other commonly used drugs in the country, the best performance of boric acid envisage the need to update the national treatment guidelines for the treatment of Candida vaginitis.

Key words: Non-albicans Candida species, azole resistance, boric acid.