Synergistic effects of silver ions and metformin against enterococcus faecalis under high-glucose conditions in vitro

• Published in: BMC microbiology 2021-09, Vol.21 (1), p.261-261, Article 261
• Main Authors: Wu, Xuying, Fan, Wei, Fan, Bing
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Animals; Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - therapeutic use; Antibacterial activity; Antibiotics; Antidiabetics; Antimicrobial agents; Bacteria; Biofilms; Biomedical materials; Chemical properties; Cholecystokinin; Cytotoxicity; Dentin; Dextrose; Diabetes; Drug Synergism; Drug therapy; Endodontics; Enterococcal infections; Enterococcus faecalis; Enterococcus faecalis - drug effects; Glucose; Glucose - metabolism; Glucose - pharmacology; Gram-positive bacteria; Gram-Positive Bacterial Infections - drug therapy; Growth curves; Hyperglycemia; Inflammation; Ions; Ions - chemistry; Ions - pharmacology; Ions - therapeutic use; Metal ions; Metformin; Metformin - pharmacology; Metformin - therapeutic use; Mice; Minimum inhibitory concentration; Pharmacology, Experimental; Physiological aspects; Silver; Silver - pharmacology; Silver - therapeutic use; Silver ion; Synergistic effect; Toxicity testing
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/s12866-021-02291-2

This study aimed to evaluate the synergistic antibacterial activities of silver ions (Ag ) and metformin hydrochloride (Met) against Enterococcus faecalis (E. faecalis) under normal or high-glucose conditions. The minimum inhibitory concentration, minimum bactericidal concentration, growth curves, and colony-forming units were used to evaluate the antibacterial effects of Ag and Met on planktonic E. faecalis in Brain Heart Infusion broth with or without additional glucose. The influences of Ag and Met on four weeks E. faecalis biofilm on human dentin slices was also tested. Cytotoxicity was tested on MC3T3-E1 osteoblastic cells using CCK-8 assays. The results indicated that E. faecalis showed higher resistance to drug treatment under high-glucose conditions. Ag (40 μg/mL) plus Met (3.2% or 6.4%) showed enhanced antibacterial activities against both planktonic E. faecalis and biofilm on dentin slices, with low cytotoxicity. Met enhanced the bactericidal effects of Ag against both planktonic and biofilm E. faecalis under normal or high-glucose conditions with low cytotoxicity. Further molecular studies are needed to be conducted to understand the mechanisms underlying the synergistic activity between Met and Ag .