Therefore, O. syriacum L., T. syriacus Boiss., C. zeylanicum L., and S. aromaticum L. could act as bactericidal agents against Gram-negative bacteria. Keywords: Gram-negative bacteria, Antibiotic resistance, Cinnamomum zeylanicum, Syzygium aromaticum Introduction Medicinal and aromatic plants are used
on a large scale in medicine against drug-resistant bacteria, which are considered one of the most important Inhibitors,research,lifescience,medical reasons for the lack of success of treatment in infectious diseases. Medicinal plants are the major sources of new medicines and may constitute an alternative to the usual drugs.1 Aromatic oils are used in many MK-0518 supplier industries, including food preservation,2 pharmacy, and medicine.3,4 They are expected to form new sources of antimicrobial drugs, especially against bacteria.5 The antibacterial effectiveness of aromatic oils has been divided into a good, medium, or bad.6,7 These oils can also produce some defense products against several Inhibitors,research,lifescience,medical natural enemies.8 In addition, and in order to continue their natural growth and development, aromatic oils may produce some secondary metabolites in response to some external stress.9 The extracts and oils of 28 plants used in this work have been traditionally employed
by people for various purposes in different Inhibitors,research,lifescience,medical parts of the world. Cinnamomum zeylanicum essential oil has antibacterial and antifungal activities10 as well as anti-diabetic properties;11 Citrus limon and Rosmarinus officinalis L. essential oils possess antioxidant properties;12,13 Citrus aurantium has immunological effects in humans;14 Eucalyptus globulus oil has good antimicrobial Inhibitors,research,lifescience,medical activities;15,16 Thymus pannonicus essential oil has an excellent effect against E. coli O157:H7;17 light thyme essential oil inhibits Inhibitors,research,lifescience,medical the growth of E. coli O157:H7 in foods;18 Brillantaisia lamium extract exhibits antibacterial and antifungal effects against Staphylococcus aureus,
Enterococcus faecalis, Candida tropicalis, and Cryptococcus neoformans;19 and finally Crinum purpurascens herb extract has antimicrobial activities against Salmonella paratyphi A and B.20 Traditionally, many plant extracts and oils are used as medicinal plants in Syria for many purposes, particularly for respiratory and gastrointestinal disorders. The aim of this study was to screen the in vitro antibacterial activity of 28 plant extracts and oils against some Gram-negative bacteria, MycoClean Mycoplasma Removal Kit including: E. coli O157:H7, Yersinia enterocolitica O9, Proteus spp., and Klebsiella pneumoniae. Materials and Methods Microorganisms and Growth Conditions Fifteen local isolates of E. coli O157:H7, Y. enterocolitica O9, Proteus spp., and K. pneumoniae were grown for 24-48 h in 2YT agar (peptone, 16 g/liter; yeast extract, 10 g/liter; NaCl, 5 g/liter; agar, 13 g/liter [Difco, BD, Spars, MD]). The bacteria were suspended in a sterile phosphate-buffered saline (PBS).