Altered oral microbiome diversity in patients with oral candidiasis

Oral candidiasis is a common opportunistic infection caused by Candida albicans, particularly in individuals with local or systemic risk factors. This study aimed to investigate how antifungal therapy affects the composition of the oral bacterial microbiome.

Unstimulated saliva samples were collected from ten patients diagnosed with acute pseudomembranous oral candidiasis before and after fluconazole treatment. Microbiome profiles were assessed using 16S rRNA gene sequencing. Quantitative PCR was performed to validate changes in specific bacterial species.

Alpha diversity did not change significantly, whereas beta-diversity analyses indicated modest compositional shifts. Antifungal therapy was associated with an increase in Streptococcus salivarius, a commensal linked to mucosal health. The signal was confirmed by species-specific qPCR in paired samples.

Fluconazole treatment for oral candidiasis induces modest shifts in the oral bacterial community, particularly increasing the abundance of S. salivarius. These changes may reflect partial recovery of microbial homeostasis, supporting the role of microbiome monitoring and probiotic approaches in post-treatment care.