In vitro activity of inexpensive topical alternatives against Candida spp. isolated from the oral cavity of HIV-infected patients

Abstract

The use of inexpensive topical alternatives, e.g. oil of melaleuca (tea tree oil (TTO)), chlorhexidine (CHX), povidone iodine (PI) and gentian violet (GV), to treat oral candidiasis in human immunodeficiency virus (HIV)-infected patients has been proposed in resource-poor countries. However, pre-clinical studies comparing the antifungal activity of these agents are lacking. This study compared the minimal inhibitory concentrations (MICs) of TTO, GV, PI, CHX and fluconazole (FLZ) against 91 clinical Candida strains using Clinical and Laboratory Standard Institute (CLSI) methodology. Isolates were obtained from the oral cavity of acquired immune deficiency syndrome (AIDS) patients. Among the topical agents examined, GV showed the most potent activity against all Candida isolates tested (MIC range, MIC for 50% of the organisms (MIC 50) and MIC for 90% of the organisms (MIC 90) of 0.03–0.25 μg/mL, 0.06 μg/mL and 0.12 μg/mL, respectively). CHX was 64 times less active than GV (MIC range, MIC 50 and MIC 90 of 0.5–16 μg/mL, 4 μg/mL and 8 μg/mL, respectively). The lowest antifungal activity was seen for PI (MIC 90 = 0.25%). Moreover, GV, unlike the other topical agents tested, was fungicidal (minimum fungicidal concentration = 1 μg/mL) against Candida albicans isolates ( n = 83). In addition, GV showed activity against FLZ-resistant C. albicans ( n = 3). The combination of GV and FLZ was not antagonistic and there was no interaction between the two compounds. GV possesses potent antifungal activity against FLZ-susceptible and -resistant Candida strains and is not antagonistic when used in combination with FLZ. In vivo evaluation is warranted.