Evaluation of antibacterial effects of ethanol extracts of Withania somnifera and Rosmarinus officinalis plants on Staphylococcus aureus isolated from sheep nose

Staphylococcus aureus considered as one of the commonest agents of bacterial food poisoning which may transfer to human from animals and animal-originated foods. Therefore, the aim of this study were isolation of the S. aureus from native sheep nose of Sistan region; evaluation of antibiotic resistance of isolated strains treated with common antibiotics; and studying the antimicrobial effects of ethanol extracts of Withania somnifera and Rosmarinus officinalis on isolated strains. A total of 15 strains of S. aureus were isolated through biochemical methods. Ethanol extracts of W. somnifera and R. officinalis obtained using Rotary apparatus and distillation in vacuum methodology. Susceptibility of the isolated strains to common antibiotics was determined via Kirby-Bauer disk diffusion standard test. Through dilution in well method susceptibility of the isolated strains were determined in treatment with ethanol extracts of W. somnifera and R. officinalis. Among evaluated antibiotics, the studied strains were not influenced by Oxacillin but Gentamicin controlled the bacterial growth completely. In comparison with R. officinalis, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of W. somnifera arises in a lower amount to inhibit the growth of the bacteria. While due to susceptibility of the bacteria to the common antibiotics, treatment of the bacteria with antibiotics resulted in rapid decreasing in the bacterial population, however, due to probable antibiotic resistance, it is recommended that antibiotics would be replaced with plant extracts. Comparison between two treated extracts in the current study have shown that ethanol extract of W. somnifera could be introduced as a suitable replacement with common antibiotics.