Metformin as a Potential Adjuvant Antimicrobial Agent Against Multidrug Resistant Bacteria

Abstract

Introduction: The continuous increase in the incidence of bacterial resistance to existing antibiotics represents a worldwide health burden. A surrogate strategy to combat such crisis is to find compounds that restore the antimicrobial activity of the already existing antibiotics against multidrug resistant bacteria. Metformin is a commonly used antidiabetic medication. It has proven benefits in other diseases including cancer, aging-related and infectious diseases. In this study, the potential effect of metformin as an adjuvant therapy to antibiotics was investigated. Methods: Two multidrug resistant bacterial strains were used; methicillin-resistant Staphylococcus aureus (MRSA; ATCC 33,591) and multidrug resistant Pseudomonas aeruginosa (ATCC BAA-2114). To assess its efficacy, metformin was combined with several antibiotics: levofloxacin, chloramphenicol, rifampicin, ampicillin, and doxycycline. The antibacterial effect of metformin was tested using the micro broth dilution method. The minimum inhibitory concentration (MIC) was also measured. Cytotoxicity studies were also performed on mammalian cells to assess its safety. Results: Metformin exhibited an antibacterial effect when combined with the antibiotics on the two tested strains. It also showed low toxicity on the mammalian cells. Moreover, synergetic studies showed that metformin enhanced the effect of the combined antibiotics, as these combinations provide either a synergistic or additive effect with significant reduction in the MIC. Conclusion:Metformin exerts an adjuvant antibacterial effect; thus, it could be a possible candidate as an adjuvant therapy to reduce antimicrobial resistance.

Metformin: Is it a drug for all reasons and diseases?

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A Critical Review of the Evidence That Metformin Is a Putative Anti-Aging Drug That Enhances Healthspan and Extends Lifespan

“…In addition to its benefits as an anti-hyperglycemic agent, metformin also lowers the atherosclerotic burden in non-diabetic persons at risk of developing T2DM (1,7). Interest in the potential clinical benefits of metformin has been extended to include repurposing for polycystic ovary syndrome (PCOS), preeclampsia, cancer, rheumatoid arthritis, malaria, and antibiotic and antiviral actions (43)(44)(45)(46)(47)(48). Based on this everexpanding catalogue of the benefits of metformin, the title of a review article refers to metformin as: "Metformin, the aspirin of the 21 st century-" (27).…”

Metformin: Activation of 5′ AMP-activated protein kinase and its emerging potential beyond anti-hyperglycemic action

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