A Modified Method Incorporating Multiplex <scp>PCR</scp> Reveals <i>Fusobacterium</i> Prevalence in Southern Chinese Population and Its Correlations in Cancers

Fusobacterium, a gram-negative anaerobic bacillus in mouth, gastrointestinal tract and elsewhere, has long been considered as opportunistic pathogen. Increasing evidence indicate the association of Fusobacterium with human diseases, especially cancer. However, previous studies demonstrated contradictory prevalent features of Fusobacterium species in normal and patient population. To address this dissonance, we developed a high-precision multiplex PCR assay that allows concurrent identification of five species of Fusobacterium (F. nucleatum, F. mortiferum, F. ulcerans, F. varium and F. necrophorum) and four subspecies of F. nucleatum (nucleatum, animalis, vincentii and polymorphum). By employing the PCR method, we investigated the prevalent features of Fusobacterium communities in Southern Chinese population and cancer patients. Surprisingly, we found F. nucleatum was dominant in both Southern Chinese population and cancer patients, and discovered the correlations of Fusobacterium species to host conditions. Moreover, F. mortiferum exhibited better diagnostic performance for cancers compared to other species, and the combination of F. mortiferum, F. nucleatum, body mass index and haemoglobin by a logistic regression model showed excellent diagnostic performances for cancers. Additionally, we determined the compositional features and loads of Fusobacterium communities in paired tumour, adjacent tissues and normal tissues of colorectal cancer and lung cancer. Hence, we developed a high-precision multiplex PCR assay to profile Fusobacterium in human faeces and tumour, and demonstrate its prevalence in Southern Chinese population with correlations to host conditions and cancers.