In the Pg and Fn co‐incubation model, the antibiotic effects of P/S and CDR on Fn markedly decreased, although both sufficiently inhibited the growth of Fn in the single‐infection organ culture model (Figure 3e and f), while MTZ exhibited relatively good responses against Fn when these bacteria were co‐incubated with Pg in organ culture (Figure 3d). This evidence concerns the gene FN1 and infection.