The Inhibitory Effect of Probiotic Bacteria against Drug - Resistant Candida Species Isolated from the Oral Cavity of the Elderly

Candidiasis includes a range of opportunistic fungal diseases that appear in various forms such as oral thrush and stomatitis in the elderly. Recently, the resistance of Candida species to antibiotics selected to treat oral infections has increased significantly.
This study aimed to determine the antagonistic effects of probiotics on oral candidiasis in the elderly.
Patients and Swab samples from the saliva and mouth of 72 elders residing in the elderly care centers in Gorgan were cultured in Sabouraud dextrose agar (SDA). The Candida spp. and Candida albicans were identified by culturing in CHROMagar Candida medium and using a PCR identification kit and API 20CAUX system. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of nystatin and itraconazole based on the CLSI document. The well - diffusion method and the modified agar method were applied to separate dairy - isolated probiotics from cultures in MRS and M17 media and to study their antimicrobial effect.
Overall, 47 Candia isolates in seven different species were diagnosed. The MICs of itraconazole and nystatin were within the range of 0.03 - 16 and 0.03 - 8 µg/mL and the rates of resistance were 87.23% and 74.46%, respectively. The study on dairies showed that most isolated strains belonged to Lactobacilli. It was also revealed that the probiotic bacteria were able to prevent the growth of Candida species. The highest inhibitory effect was seen in Lactobacillus plantarum. Moreover, desirable antifungal effects were observed in preventing the growth of C. albicans as well as non - albicans species, particularly C. glabrata.
Concerning the high resistance of Candida isolates to antifungal agents and the inhibitory effects of lactic bacteria, especially Lactobacillus plantarum, it is recommended to use its metabolites directly in the diet of the elderly or to use them in the form of supplements in order to control oral candidiasis.