FN1 and infection: The invasion of Fn into host cells may contribute to increased resistance to antibiotics, leading to secondary infections.9 To assess the efficacy of commonly used antibiotics against intracellular Fn, in addition to gentamicin, we selected metronidazole and amoxicillin, two widely prescribed treatments for oral inflammation.48 We first demonstrated that extracellular Fn in the apical chamber of the asymmetric coculture was effectively inhibited by individual antibiotics, reducing bacterial counts by over three orders of magnitude compared to the untreated group (Fig. S8).