Salvia officinalis L. plant is one the most popular medicinal and aromatic plant species belongs to Lamaiceae family[1]. A greenhouse experiment was carried out to determine the antimicrobial activty of S. officinalis L. plants inoculated with four rhizobacteria strains namely Pseudomonas fluorescens (Pf Ap1, Pf Ap18) and P. putida (Pp Ap9, Pp Ap14). rhizobacteria suspensions were diluted in sterile distilled water to achieve the final concentration of 108 CFU ml-1. The suspensions were subsequently applied to the soil, cuttings and leaves.Totally, 60 ml of the final suspension was applied for each treatment The control cuttings received the same amount of distilled water. The experiment was arranged based on completely randomized design and replicated at three times. Plants were harvested after four months at the full flowering stage. Essential oils (EOs) were obtained by hydrodistillation method using a Clevenger-type apparatus for 3 h. In vitro antibacterial efficacy of the reference EOs were tested against three Gram-positive bacteria including Staphylococcus aureus PTCC 1431, Staphylococcus epidermidis PTCC 1114, Enterococcus faecalis PTCC 1394, and three Gram-negative ones namely P. aeroginosa PTCC 1310, Escherichia coli PTCC 1396 and Kelebsiella pneumonia PTCC 1290. The test was based on disc diffusion method using Muller-Hinton Agar (MHA) according to the National Committee for Clinical Laboratory Standard [2]. The highest activity was observed for the EOs extracted from plants inoculated with Pp Ap14 against S. aureus with maximum inhibition zone (IZ, 29.5 mm), a minimum inhibitory concentration (MIC) value of 0.5 μg ml-1 as well as a minimum bactericidal concentration (MBC) value of 2 μg ml-1. Therefore, S. aureus could be considered as the most susceptible bacterium tested. In contrast, K. pneumonica with the lowest mean diameter of IZ, and with MIC and MBC values mostly higher than those of the other test organisms was found as the most resistant pathoge
