Metformin Susceptibility of Oral Pathogens Contributing to Periodontal Disease

Objectives: Amongst the variety of drugs utilized in the treatment of diabetes mellitus, Metformin, an antihyperglycemic drug, consistently remains the preferred, and most common, pharmaceutical prescribed to Type 2 diabetics. Beyond its main mechanism of lowering plasma glucose levels, Metformin has interestingly been found to affect the levels of thriving bacteria, especially when tested with gut microbiota. Previously, research has demonstrated that Metformin may be able to act as an antibacterial against bacteria present in common infections. This may suggest that the higher incidence of periodontal disease in diabetic patients can possibly be treated with this already existing drug. However, Metformin’s effect on oral pathogens has not yet been researched, therefore it is important to be able to implicate Metformin as an antibacterial against not only other various strains that exist, but more specifically, against oral pathogens that contribute to periodontal disease.
Methods: For the following study, Streptococcus mutans, Porphyromonas gingivalis, and Fusobacterium nucleatum, were used as representatives of significant oral pathogens involved in periodontal disease. The effect of Metformin on Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis were also observed in the study. These strains were tested for their susceptibility to Metformin treatment, and minimal inhibitory concentrations established, as well as Metformin’s ability to inhibit growth of these cultures via broth macrodilution and spread plating.
Results: From the experiments, it was demonstrated that Metformin treatment resulted in significant inhibition when administered at high concentrations. Metformin treated samples showed decreased growth of colonies as compared to the control, non-treated samples of the bacterium tested.
Conclusions: By testing the susceptibility of these oral pathogens to Metformin, it will be possible to further study its mechanism of inhibition and utilize it in the treatment of periodontal disease by practically manipulating existing drugs to be applied in a versatile clinical environment.