Molecular detection of toxigenic Clostridioides difficile in subgingival biofilm of severe periodontitis.

OBJECTIVES: The oral cavity is the main gateway for the entry of C. difficile spores to the digestive tract. In conditions of poor oral hygiene and periodontal diseases, the dysbiotic oral microbiota may be a reservoir for several human pathogens. Here, we explored the prevalence of C. difficile in the oral microbiota of patients with severe periodontitis by the molecular detection of species specific genes. METHODS: Subgingival biofilm, saliva and/or feces from 659 patients with gingivitis, periodontitis and no periodontal diseases were screened for the tpi and toxin A/B genes specific for C. difficile by multiplex PCR. Differences among groups were sought by the Chi-square test. RESULTS: The overall frequency of C. difficile tpi gene was 29 %, with a high detection of tcdB gene (44.8 %). Patients with periodontitis showed a greater prevalence of this gene in the biofilm than individuals with gingivitis and periodontal health (p = 0.001), particularly at more severe stages of disease (p < 0.05). No toxin genes were detected in feces or biofilm from healthy patients, whereas >70 % of the biofilm from patients with periodontal diseases were positive for these genes (p < 0.001). Detection of C. difficile tpi gene in oral/fecal samples correlated with periodontal inflammation (p < 0.05). A modest intra-individual agreement between tpi gene detection in feces and saliva was found within periodontitis patients (Kappa = 0.314; p = 0.003). CONCLUSION: The high frequency of the C. difficile specific genes tpi and tcdB in the dysbiotic subgingival biofilm of advanced periodontitis could support the presence of the bacterium in this niche.