Betanin from beetroot enhanced survival of Caenorhabditis elegans infected with methicillin-resistant Staphylococcus aureus

Aims: Betanin is a red plant pigment belonging to the group called betalain. This present study aimed at investigating the effect betanin from beetroot (Beta vulgaris subsp. vulgaris) as a potential anti-infective agent against methicillin-resistant Staphylococcus aureus (MRSA) using a Caenorhabditis elegans infection model. Methodology and results: The minimum inhibitory concentration of betanin against MRSA strain ATCC 33591 was determined to establish the non-inhibitory concentration. The minimum inhibitory concentration of betanin against MRSA was > 20 mg/mL. C. elegans were then infected with MRSA and treated with betanin at different concentrations (100, 200, 300 and 400 μg/mL). Betanin at 200 μg/mL significantly improved worm survival following infection whereby the mean time to death was extended about 76 h upon treatment. Intestinal colonization by MRSA of worms exposed to betanin extract was similar to non-betanin-treated infected worms. Conclusion, significance and impact of study: The enhanced survival of MRSA-infected worms upon betanin treatment was not a result of the activation of the host antimicrobial mechanism. Betanin from beetroot can be potentially used as a natural anti-infective agent as a mean to reduce antimicrobial resistance of S. aureus or used in combination with established antimicrobials to increase their effectiveness.