Probiotic Interference of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 with the Opportunistic Fungal Pathogen Candida albicans

Candida albicans is the most important Candida species causing vulvovaginal candidiasis (VVC). VVC has significant medical and economical impact on women's health and wellbeing. While current antifungal treatment is reasonably effective, supportive and preventive measures such as application of probiotics are required to reduce the incidence of VVC. We investigated the potential of the probiotics Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 towards control of C. albicans. In vitro experiments demonstrated that lactic acid at low pH plays a major role in suppressing fungal growth. Viability staining following cocultures with lactobacilli revealed that C. albicans cells lost metabolic activity and eventually were killed. Transcriptome analyses showed increased expression of stress-related genes and lower expression of genes involved in fluconazole resistance, which might explain the increased eradication of Candida in a previous clinical study on conjoint probiotic therapy. Our results provide insights on the impact of probiotics on C. albicans survival.