Antimicrobial and immunomodulatory in vitro profile of double antibiotic paste

Aim To evaluate the antimicrobial and immunomodulatory activity of double antibiotic paste (DAP) in an in vitro infection model. Methodology The minimum inhibitory and bactericidal concentrations (MIC and MBC) and the antibiofilm activities (TTC assay) of DAP and its components (ciprofloxacin and metronidazole) were evaluated against Staphylococcus aureus and Enterococcus faecalis compared with triple antibiotic paste (TAP). The cellular viability of RAW 264.7 macrophages (24 and 72 h) and L929 fibroblasts (48 and 72 h) was evaluated by MTT. Furthermore, the production of TNF‐α, IL‐12, IL‐6, IL‐1α, IL‐10 and NO (on RAW 264.7), besides IL‐6, TGF‐β and NO (on L929), stimulated with DAP in baseline and associated with heat‐killed microbial‐antigen conditions was measured by ELISA and Griess reaction. Data were analysed using the one‐way ANOVA test with Bonferroni's corrections. Results The MBC of pharmacopoeia DAP was similar to TAP for E. faecalis (0.25 μg. mL−1) and lower for S. aureus (DAP 1 μg. mL−1 and TAP 2 μg. mL−1; p