Antibacterial and antibiofilm activities of nanoemulsioncontaining Nigella sativa essential oil on multi-drug resistant strains ofStaphylococcus aureus and Pseudomonas aeruginosa.

Background and Aim : Multidrug-resistant (MDR) bacteria are an increasing threat to publichealth, leading to the constant use of higher doses of antibiotics. Nigella sativa essential oil (NS)has antibacterial properties attributed to its thymoquinone. On the other hand, nanoemulsions (NE)can increase the penetration of the active ingredients. Therefore, this study aimed to investigatethe antibacterial and antibiofilm activities of NE containing NS (NE-NS) on MDR strains ofStaphylococcus aureus (Staph.A) and Pseudomonas aeruginosa (Pseudo.A) isolated from hospitalpatients.Methods : After analysis of compounds of NS using GC-MS, the most stable NE-NS was preparedusing ۵% NS, ۳۰% (v/v) surfactant (۱۷.۶۴% Tween-۲۰ and ۱۲.۳۶% Tween-۸۰), and ۶۵% (v/v) ofthe aqueous phase and was characterized by the dynamic light scattering (DLS) method. Thenantibacterial and antibiofilm activities were determined by minimum inhibitory concentration(MIC) and minimum biofilm inhibitory concentration (MBIC), respectively, using brothmicrodilutionResults : GC-MS analysis showed ۸ hydrocarbon monoterpene components which thymoquinonebeing the most primary with ۹۲.۹۶%. DLS showed a mean droplet diameter of ۵۸.۷ nm with apolydispersity index of ۱.۰۱۶. There is a significant decrease of MIC on the Staph.A. for NScompared to NE-NS from ۱.۵۶ to ۰.۱۹ μl/ml (۴ fold) and a significant decrease of MBIC from ۱۲.۵to ۶.۲۵ μl/ml (۲ fold). However, these activities were not significant to Pseudo.A.Conclusion : Thymoquinone is an active ingredient that had more antibacterial and antibiofilmactivities on Staph.A. than Pseudo.A., which these activities improved by NE only about Staph.A.This can be due to the lipopolysaccharide cell wall in Gram-negative Pseudo.A, which preventsactive compounds from entering the cytoplasmic membrane.

کلیدواژه ها:

Nigella sativa essential oil ، Nanoemulsion ، Antimicrobial ، antibiofilm ، multidrugresistant