A Droplet Digital PCR Approach for the Quantitative Detection of Fusobacterium nucleatum in Formaldehyde-Fixed, Paraffin-Embedded Tumor Tissues.

Fusobacterium nucleatum, a prevalent component of the intratumoral microbiome, has been associated with reduced survival in colorectal cancer. To enable sensitive and specific detection of F. nucleatum in tumor specimens, we developed a droplet digital PCR (ddPCR) assay targeting the transcription termination/anti-termination gene nusG, normalized to host tissue content using the solute carrier organic anion transporter family member 2A1 gene, SLCO2A1. Here, we present a ddPCR protocol optimized for quantifying F. nucleatum DNA in human genomic DNA extracted from formalin-fixed, paraffin-embedded (FFPE) tumor tissues. This methodology has been refined for high-throughput application, supporting large-scale analyses of F. nucleatum prevalence in tumor samples.