Evaluation of essential oil obtained from × L. against multidrug-resistant strains.

Background: Bacterial multidrug resistance currently poses an increasingly serious threat, with important clinical consequences regarding treatment options. In 2017, the WHO released a global list of resistant bacteria, identifying multidrug-resistant (MDR) Gram-negative bacteria such as carbapenem-resistant or , extended-spectrum cephalosporin-resistant as critical priorities for developing new strategies of treatment.

Purpose: The novelty presented in this study refers to the evaluation of the volatile oil obtained from the leaves of × L., on MDR strains from hospitalized patients.

Material And Methods: The essential oil was extracted by steam distillation and tested on six reference bacterial strains and also on the MDR strains collected from patients of the "Pius Brînzeu" Emergency Clinical County Hospital Timișoara. The in vitro antibacterial activity was evaluated by agar disk diffusion method and microdilution method.

Results: Testing the antibacterial activity of peppermint oil on both reference strains and isolated MDR strains from hospitalized patients demonstrated its bactericidal effect. Minimum inhibitory concentration (MIC) was lower (20 mg/mL) for and and higher (40 mg/mL) for and strains. Minimum bactericidal concentration (MBC) was equal to MIC, with the exception of strains, where MBC was the double of MIC.

Conclusion: The present study highlights the bactericidal activity of × L. essential oil on all tested MDR or extensively drug-resistant Gram-positive and Gram-negative strains of pneumoniae, and . This oil may be a therapeutic option in the near future for many infectious diseases produced by MDR bacteria.