Heparin-benzyl alcohol enhancement of biofilms formation and antifungal susceptibility of vaginal Candida species isolated from pregnant and nonpregnant Saudi women

Biofilm formation by Candida species is a major contribute to their pathogenic potential.The aim of this study was to determine invitro effects of EDTA, cycloheximide, and heparin-benzyl alcohol preservative on C. albicans (126) and non-albicans (31)vaginalyeast isolates biofilm formations and their susceptibility against three antifungal Etest strips. Results of the crystal violet-assay,indicated that biofilms formation were most commonly observed [100%] for C. kefyr, C. utilis, C. famata, and Rhodotorulamucilaginosa, followed by C. glabrata [70%], C. tropicalis [50%], C. albicans [29%], Saccharomyces cerevisiae [0.0%]. EDTA (0.3mg/ml)significantly inhibited biofilm formation in both C. albicans and non-albicans isolates (P=0.0001) presumably due to chelation ofnecessary metal cations for the process-completion. In contrast, heparin (-benzyl alcohol preservative) stimulated biofilm formationin all tested isolates, but not at significant level (P=0.567). Conversely, cycloheximide significantly (P=0.0001) inhibited biofilmformation in all C. albicans strains(126) and its effect was even 3 fold more pronounced than EDTA inhibition, probably due to itsattenuation of proteins (enzymes) and/or complex molecules necessary for biofilm formation. Results also showed that all nonalbicansyeasts isolates were susceptible to 5-flucytosine (MIC₅₀, 0.016 µg/ml; MIC₉₀, 0.064 µg/ml), but 14% of C. albicans isolateswere resistant (MIC₅₀, 0.064 µg/ml; MIC₉₀ >32 µg/ml). The MIC₅₀ value of amphotricin B for all C. albicans and non-albicans isolateswas at a narrow range of 0.023 µg /ml, and the MIC₉₀ values were 0.047 µg/ml and 0.064 µg/ml respectively, thereby confirmingits efficacy as a first line empiric- treatment of Candida spp infections.