Candida albicans as Marker of the Impact of Antibiotics on Gut Microbiome

Background: Candida albicans constitutes part of the normal human gastrointestinal (GI) microbiome(GM). Alterations inthe GM induced by antibiotics may disrupt colonization resistance and promote fungal overgrowth. This review summarizes the effects of antibiotics on GI C. albicans colonization in experimental animal models and humans. Methods: A narrative review was conducted using data from the PubMed/MEDLINE and Scopus databases. Studies evaluating changes in GI C. albicans populations following antibiotic administration in mice or humans were included. Results: Twenty-six articles met the inclusion criteria, comprising 16 murine and 10 human studies. Across all studies, antibiotics were consistently associated with increased GI C. albicans colonization. The greatest increases were observed with broad-spectrum agents with activity against anaerobic bacteria. Elevated fungal concentrations frequently persisted after treatment discontinuation. Human studies largely reproduced findings from murine models. Despite substantial increases in GI colonization, dissemination beyond the GI tract was uncommon. Conclusions: Available evidence demonstrates that antibiotic-induced disruption of the GM promotes GI overgrowth of C. albicans. Hence, C. albicans concentration can serve as an indicator of antibiotics’ impact on the GM. While increased colonization alone rarely results in invasive disease, antibiotic-associated yeast expansion may represent an important step in the pathogenesis of disseminated candidiasis.