A Versatile Nanoemulsion of Antibiotic and Eucalyptol with Synergistic Effects Against E. Coli Infected Urocystitis

Abstract

The extensive use and misuse of antibiotics have resulted in bacterial resistance becoming increasing commonplace. Essential oils (EOs) are known to possess antimicrobial properties and therefore have many potential practical applications. However, the default of hydrophobicity, chemical instability, and volatility limit scope of application. Encapsulation of EOs in colloidal delivery systems can mitigate these challenges and allow for greater efficacy. A homogenous nanoemulsion (HS15‐CE) containing a combination of eucalyptol (Euc) and cefradine (Cef) is developed to explore its synergistic effect on antibacterial activity and potentially reduce the amount of antibiotic required to treat bacterial infections. The HS15‐CE nanoemulsion displays a synergistic effect on the inhibition of Escherichia coli (E. coli) growth in vitro, significantly decreasing the minimum inhibitory concentration (MIC) by eight times. The ex vivo imaging reveals high accumulation concentrations and long retention in bladders. Moreover, the nanoemulsion alleviates the E. coli induced cystitis infection, as evidenced by decreased bacterial colonies in urine, reduced inflammatory cytokines, and increased expression of tight junctional protein ZO‐1. These findings suggest the potential of the HS15‐CE nanoemulsion in providing a synergistic effect for the treatment of bacterial urocystitis.