STUDY OF THE ANTIBACTERIAL ACTIVITY OF ESSENTIAL OILS OF CERTAIN PLANTS ON ISOLATED BACTERIA OF MAMMARY MILK IN ALGERIA

The infection or inflammation of the mammary gland represents a dominant pathology in dairy cattle. The aim of this work was to study in vitro the antimicrobial activity of essential oils of some plants on bacteria which were isolated from mammary milk. The essential oils of Thymus vulgaris, Rosmarinus officinalis, Artimisia herba alba and Myrtus communis were obtained by hydro distillation of the aerial part. They were tested on strains of staphylococci that were multi-resistant to antibiotics which are isolated from mammary milk. The essential oils contents are between a low value of 0.3% for Myrtus communis and a relatively high value of 2.5% for Thymus vulgaris. The different essential oils tested revealed interesting antimicrobial activities. The strongest antibacterial activity was observed for the essential oil of Thymus vulgaris (9-52 mm), while the oils of Rosmarinus oficinalis, Artimisia herba alba and Myrtus communis showed moderate antimicrobial activities (9-19.5 mm). We also determined the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and the MIC / MBC ratio of Thymus vulgaris on the three multi-resistant strains of staphylococci; it turned out that MIC ranged between 0.01 and 0.016 µg / ml and MBC ranged between 0.021 and 0.078 µg / ml. In the conclusion, Thymus vulgar is revealed a bactericidal effect on the strains tested.