Antimicrobial activity of five essential oils against origin strains of the Enterobacteriaceae family.

An in vitro assay measuring the antimicrobial activity of essential oils of Coridothymus capitatus (Spanish origanum), Satureja montana, Thymus mastichina (Spanish Origanum majorana), Thymus zygis (Spanish variety of Thymus vulgaris) and Origanum vulgare has been carried out against poultry origin strains of Escherichia coli, Salmonella enteritidis and Salmonella essen, and pig origin strains of enterotoxigenic E. coli (ETEC), Salmonella choleraesuis and Salmonella typhimurium. Using the broth microdilution method, all the essential oils showed an MIC > or = 2% (v/v) for the two strains of E. coli. The essential oil that showed the highest antimicrobial activity against the four strains of Salmonella was Origanum vulgare (MIC < or = 1% v/v), followed by Thymus zygis (MIC < or =2% v/v). Thymus mastichina inhibited all the microorganisms at the highest concentration, 4% (v/v), while the rest of the essential oils showed highly variable results. By chemotyping, higher inhibitory capacity was observed in the oils with a higher percentage of phenolic components (carvacrol and thymol) in comparison with oils containing the monoterpenic alcohol linalool. The results of this work confirm the antimicrobial activity of some essential oils, as well as their potential application in the treatment and prevention of poultry and pig diseases caused by salmonella.