Antibacterial activity of plant extracts and phytochemicals on antibiotic-resistant bacteria

The antimicrobial activity of plant extracts and phytochemicals was evaluat ed with antibiotic susceptible and resistant microorganisms. In addition, t he possible synergistic effects when associated with antibiotics were studi ed. Extracts from the following plants were utilized: Achillea millifolium (yarrow), Caryophyllus aromaticus (clove), Melissa officinalis (lemon-balm) , Ocimun basilucum (basil), Psidium guajava (guava), Punica granatum (pomeg ranate), Rosmarinus officinalis (rosemary), Salvia officinalis (sage), Syzy gyum joabolanum (jambolan) and Thymus vulgaris (thyme). The phytochemicals benzoic acid, cinnamic acid, eugenol and farnesol were also utilized. The h ighest antimicrobial potentials were observed for the extracts of Caryophyl lus aromaticus and Syzygyum joabolanum, which inhibited 64.2 and 57.1% of t he tested microorganisms, respectively, with higher activity against antibi otic-resistant bacteria (83.3%). Sage and yarrow extracts did not present a ny antimicrobial activity. Association of antibiotics and plant extracts sh owed synergistic antibacterial activity against antibiotic-resistant bacter ia. The results obtained with Pseudomonas aeruginosa was particularly inter esting, since it was inhibited by clove, jambolan, pomegranate and thyme ex tracts. This inhibition was observed with the individual extracts and when they were used in lower concentrations with ineffective antibiotics.