Abstract

Vulvovaginal Candidiasis (VVC) is a frequently observed condition during pregnancy caused by the organism known as Candida albicans. The ability of Candida to form a biofilm and its capability of being resistant to antifungal medication makes treating this condition complicated. Therefore, the purpose of this study was to evaluate the antifungal and antibiofilm properties of the human antimicrobial peptide, LL-37, against Candida isolated from pregnant women with VVC; also, to investigate whether LL-37 affects the expression of the FKS1 gene. Vaginal swabs were cultured from 150 symptomatic pregnant women in Baghdad. Candida species were identified using the chromogenic medium, the VITEK-2 system, and PCR for 18S rRNA. The susceptibility of each isolate to antifungal agents was determined using the disk diffusion method. Biofilm formation was measured using the microtiter plate method. The MIC of LL-37 was determined using the broth microdilution method according to CLSI M27-A3 guidelines. Briefly, LL-37 was serially diluted two-fold in RPMI-1640 medium (pH 7.0) in 96-well plates at concentrations ranging from 7.8 to 500 µg/mL. A standardized inoculum of 0.5–2.5 × 10³ CFU/mL was added to each well and plates were incubated at 35°C for 48 hours. The MIC was defined as the lowest concentration that inhibited visible fungal growth. The expression of the FKS1 gene was evaluated using RT-qPCR. A total of 90 Candida isolates represented by 33.3% were identified as C. albicans. Of the 30 C. albicans isolates that were identified, 53.3% produced a thick biofilm and 60% were resistant to fluconazole. LL-37 demonstrated a minimum inhibitory concentration (MIC) against Candida albicans ranging from 62.5 to 250 µg/ml. Further testing established that the three separate isolates tested (each represented a different strain of Candida albicans) had their FKS1 expression significantly downregulated following LL-37 treatment by 48%, 66%, and 95%, respectively (p < 0.05). These results demonstrate that LL-37 is a novel agent that may be used to treat vulvovaginal candidiasis in pregnant women by exhibiting potent antifungal effects and antibiofilm capabilities against C. albicans. Additionally, down-regulation of the FKS1 gene is one of the mechanisms through which LL-37 may exhibit its antifungal effects.