Antimicrobial Activity of Extracts from Satureja khuzistanica, Peganum harmala, Satureja sahendica on Planktonic Growth and Biofilm Formation of Staphylococcus aureus

Staphylococcus aureus is one of the most important pathogenic bacteria in humans. Due to the antibiotic resistance, treatment of staphylococcal infections is difficult. Among the alternative treatment options, plants are considered as a rich source of material with antimicrobial activity. The aim of this study was to evaluate of the antimicrobial effects of ethyl acetatic, methanolic and water-methanolic extracts from Satureja khuzistanica, Peganum harmala, Satureja sahendica onplanktonic growth and biofilm formation of S. aureus.

The extracts were prepared from different parts of plants and the antimicrobial properties of the extracts were determined by disk diffusion and microbroth dilution method. Also, Crystal violet staining assay was used to evaluate the ability to inhibit biofilm formation of S. aureus strains. Disruption of pre-formed biofilms of S. aureus strains were evaluated following exposure to plant extracts in different concentrations (ranging from 3/125 to 400mg/ml).

The highest inhibitory zones were showed by ethyl acetatic extract of Satureja sahendica (28/6±0.6mm). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethyl acetatic extract of S.khuzistanica were 1/562 and 3/125mg/ml, respectively. Besides, methanolic extract of S. khuzistanica was the most effective extract in inhibition of microbial cells attachment to surface (57/89%) and it showed disruption of pre-formed biofilms at the concentration of 50 mg/ml.

The extracts of all mentioned plants had satisfactory antimicrobial effects against the planktonic growth of S. aureus and methanolic extract of S. khuzistanica was effective against biofilm formation of S. aureus.