Oral Microbial Changes in Oral Squamous Cell Carcinoma: Focus on Treponema denticola, Lactobacillus casei, and...

Background and Objectives: In this study, we aimed to explore the oral bacteria and fungi that can help discern oral squamous cell carcinoma (OSCC) and investigate the correlations between multiple key pathogens. Materials and Methods: Twelve participants (8 females and 4 males; mean age, 54.33 ± 20.65 years) were prospectively recruited into three groups: Group 1: healthy control, Group 2: patients with stomatitis, and Group 3: patients with OSCC, with 4 individuals in each group. Unstimulated whole saliva samples from these participants were analyzed using real-time PCR to assess the presence and abundance of 14 major oral bacterial species and Candida albicans. Results: The analysis revealed significant differences for certain microorganisms, namely, Treponema denticola (T. denticola), Lactobacillus casei (L. casei), and Candida albicans. T. denticola was most abundant in the OSCC group (5,358,692.95 ± 3,540,767.33), compared to the stomatitis (123,355.54 ± 197,490.86) and healthy control (9999.21 ± 11,998.40) groups. L. casei was undetectable in the healthy control group but was significantly more abundant in the stomatitis group (1653.94 ± 2981.98) and even higher in the OSCC group (21,336.95 ± 9258.79) (p = 0.001). A similar trend was observed for C. albicans, with DNA copy numbers rising from the healthy control (464.29 ± 716.76) to the stomatitis (1861.30 ± 1206.15) to the OSCC group (9347.98 ± 5128.54) (p = 0.006). The amount of T. denticola was positively correlated with L. casei (r = 0.890, p < 0.001) and C. albicans (r = 0.724, p = 0.008). L. casei's DNA copy number was strongly correlated with C. albicans (r = 0.931, p < 0.001). These three oral microbes exhibited strong positive correlations with each other and had various direct or indirect relationships with other species. Conclusions: In the OSCC group, T. denticola, L. casei, and C. albicans exhibited strong positive correlations with one another, further emphasizing the need for a deeper understanding of the complex microbial interactions in the OSCC environment.