Hossein Saghi
Abbas Bahador
Azad Khaledi
Ramazanali Ataee Kachoei
Ferdoes Amiri Dastjerdi
Davoud Esmaeili

Background: Infection due to Acinetobacter baumannii has become a significant challenge to modern healthcare systems. The rapid emergence and global dissemination of A. baumannii as a major nosocomial pathogen is remarkable and it demonstrates its successful adaptation to the ۲۱st century hospital environment. Recent studies have discussed about essential oil of Origanum vulgare against a range of bacteria, including various species of Staphylococcus, Pseudomonas, Bacillus and Escherichia coli. Objectives: The present study aimed to investigate the inhibitory effects O. vulgare essence against multidrug-resistant (MDR) strains of A. baumannii from selected hospitals in Tehran, Iran. Materials and Methods: This oil was obtained using the hydrodistillation method and analyzed by gas chromatography mass spectrography (GC/MS). The antimicrobial activity against MDR isolates was achieved using disc diffusion method and macro-broth dilution assay. Results: Analysis of the essential oil revealed the presence of pulegone (۶۸.۵۹%) piperitone (۷.۸%), piperitenone (۷.۸%), ۱, ۸-cineole (۱.۳%), and carvacrol (۱.۶%) as the major components. The results showed a significant activity against MDR A. baumannii with inhibition zones and minimal inhibitory concentration values in the ranges of ۷-۱۵ mm and ۲۰-۳۵ µL/mL respectively. Conclusions: This investigation showed that the essence oil of O. vulgare had a potent antimicrobial activity against MDR A. baumannii. Further research is required to evaluate the practical values of therapeutic applications.