Antimicrobial and Synergistic Potential of t-cinnamaldehyde Nano-emulsion Combined with Commercially Available Antimicrobials against Methicillin-resistant Staphylococcus aureus

Introduction: MRSA has emerged as an epidemic crisis in clinical, veterinary medicine and food safety worldwide. t-cinnamaldehyde is well known as a natural antimicrobial and a good source of combination therapy. However, its application is limited due to high minimum inhibitory concentration (MIC) and insolubility in water. Nano-emulsion technology may offer a solution.

Purpose: The present study was aimed to evaluate antimicrobial and synergistic potential of t-cinnamaldehyde nano-emulsion combined with commercially available antimicrobials against Methicillin-Resistant Staphylococcus aureus.

Methods: The t-cinnamaldehyde nano-emulsion was formulated using ultrasonication and tween 80 as emulsifier. Antimicrobial efficacy and synergistic potential of t-cinnamaldehyde nano-emulsion was evaluated against hospital-acquired (HA) and community-acquired (CA) MRSA strains using broth-dilution test and checkerboard assay.

Results: The t-cinnamaldehyde nano-emulsion showed minimum inhibitory concentration (MIC) of 312.5 µl/l against both CA and HA MRSA strains. Synergism analysis with commercial antimicrobials such as cefoxitin, tetracycline, erythromycin, ciprofloxacin, and vancomycin showed additive interaction with cefoxitin, tetracycline, erythromycin.

Significance: Antimicrobial nano-emulsion of t-cinnamaldehyde and its combinations with commercial antimicrobials offer alternatives to control MRSA in hospital, community and food processing settings.