The role of intestinal Candida albicans in bacterial sepsis, in the absence of candidemia, was investigated in murine models. Live C albicans or normal saline solution (NSS) was administered orally once, followed by 5 days of daily oral antibiotic-mixtures (ATB). Cecal ligation and puncture (CLP) was then performed to induce sepsis.
Fecal Candida was detected by culture only in models with Candida administration. Oral Candida administration with/without ATB enhanced gut-pathogenic bacteria as determined by microbiome analysis. Despite negative candidemia, serum (1→3)-β-D-glucan (BG) was higher in CLP with Candida preconditioning models than in CLP-controls (NSS-preconditioning) at 6 and/or 18 h post-CLP. Blood bacterial burdens were not increased with Candida administration.
Additionally, CLP with high-dose Candida (106 colony forming units) induced higher levels of fecal Candida, serum BG, serum IL-6, and mortality than the lowest dose (100 colony forming units). Interestingly, fluconazole attenuated fecal Candida and improved survival in mice with live-Candida administration, but not in the CLP-controls. Heat-killed Candida preparations or their supernatants reduced bone marrow-derived macrophage killing activity in vitro but enhanced cytokine production.
In conclusion, intestinal abundance of fungi and/or fungal-molecules was associated with increased bacterial sepsis severity, perhaps through cytokine storm induction and/or decreased macrophage killing activity. These observations suggest that further investigation of the potential role of intestinal fungal burdens in sepsis is warranted.