To investigate the presence of E. coli genes that are commonly found in AIEC and which might be relevant to oncogenesis, we quantified the presence of ClB (part of the pks genomic island) and afaC (present in all operons of the afimbrial adhesin family) in paired CRC samples; pks+ E. coli has previously been detected in 55–67% of CRC patients [22,47], compared to 8% of healthy controls [22]. This evidence concerns the gene CLYBL and colorectal carcinoma.