Multi-drug resistant bacteria (MDR) such as MDR Acinetobacter baumanii and carbapenem-resistant Klebsiella pneumonia have become a global concern in recent decades. In this study, S. rechingeri essential oil was analyzed by GC and GC-MS. After that, different nanoemulsions were produced and the optimum formulation was chosen. In addition, the antibacterial activity of the optimum formulation was evaluated against some strains of A. baumanii and K. pneumoniae. Results showed that carvacrol was the main compound of the essential oil (81.55%) and C3 nanoemulsion with a particle size of 93.14 ± 3.95 nm was the optimum and stable formulation. The antibacterial activity assessment revealed that the C3 nanoemulsion also had better antibacterial activity than essential oil. The herbal formulation had comparable antibacterial activity in comparison with six assessed antibiotics. Overall, nanoencapsulated essential oil of S. rechingeri is a candidate for producing a new generation of natural antibacterial compounds against MDR pathogens.
