Nano-encapsulated Melissa officinalis Essential Oil and Its Antibacterial Effects Against Multi Drug Resistant E. coli and K. pneumonia.

Urinary tract infections (UTIs) are common bacterial infections in children, frequently caused by E. coli and K. pneumoniae, whose biofilm-forming ability makes them resistant to antibiotics. In order to investigate an alternate drug delivery system to combat the microbial resistance, M. officinalis essential oil with its inherent antimicrobial properties was loaded in solid lipid nanoparticles (SLN) to properly enhance its antibacterial effects. Physico-chemical evaluations along with antibacterial assessment were conducted. Dynamic light scattering (DLS) results revealed that SLNs had an average size of 138.8 ± 34.3 nm and a zeta potential of -32.3 mV. Transmission electron microscopy (TEM) images confirmed their cuboid structure and smooth surface. The encapsulation efficiency of MO-SLN was 83 ± 2.1% and cumulative oil release from MO-SLN was 86.34 ± 0.1 in 72 h. The antibacterial activity of MO-SLN and MO were reported with MIC and MBC values of 545-570 µgmL^-1, 1240-1260 µgmL^-1 and 365-395 µgmL^-1, 925-955 µgmL^-1 for MDR E. coli and K. pneumoniae, respectively. Consequently, MO-SLN significantly reduced the MIC compared to pure MO, indicating that SLN as a nanocarrier can significantly increase the antibacterial effects of Melissa officinalis essential oil.