Abstract:The considerable therapeutical problems of persistent infections caused by multidrug-resistant bacterial strains constitute a continuing need to find effective antimicrobial agents. The aim of this study was to demonstrate the activities of basil (Ocimum basilicum L.) and rosemary (Rosmarinus officinalis L.) essential oils against multidrugresistant clinical strains of Escherichia coli. A detailed analysis was performed of the resistance of the drug to the strains and their sensitivity to the tested oils. The antibacterial activity of the oils was tested against standard strain Escherichia coli ATCC 25922 as well as 60 other clinical strains of Escherichia coli. The clinical strains were obtained from patients with infections of the respiratory tract, abdominal cavity, urinary tract, skin and from hospital equipment. The inhibition of microbial growth by both essential oils, presented as MIC values, were determined by agar dilution. Susceptibility testing to antibiotics was carried out using disc diffusion. The results showed that both tested essential oils are active against all of the clinical strains from Escherichia coli including extended-spectrum β-lactamase positive bacteria, but basil oil possesses a higher ability to inhibit growth. These studies may hasten the application of essential oils in the treatment and prevention of emergent resistant strains in nosocomial infections.

Acinetobacter sp. represent an important cause of nosocomial infections. Their resistance to some antibiotics, their ability to survive on inanimate surfaces in the hospital environment and their ability to produce biofilms contributes to their virulence. The aim of the study was to determine the antibacterial properties of cinnamon, lavender and geranium essential oils against bacteria of the genus Acinetobacter isolated from several clinical materials and from the hospital environment. A comprehensive evaluation of the susceptibility of Acinetobacter sp. clinical strains to recommended antibiotics was performed. The constituents of cinnamon, lavender and geranium essential oils were identified by GC-FID-MS analysis, and their Minimal Inhibitory Concentrations (MICs) against tested clinical strains were determined by the micro-dilution broth method. In addition, the effects of essential oils on the viability of human microvascular endothelial cells (HMEC-1) and glioblastoma cell line (T98G) were evaluated. Cinnamon bark oil was the most active against clinical and environmental strains of Acinetobacter baumannii with MIC values OPEN ACCESSMolecules 2014, 19 20930 ranging from 0.5 to 2.5 µL/mL. The MIC values for geranium oil were between 7.5 and 9.5 µL/mL, and between 10.5 and 13.0 µL/mL for lavender oil. These essential oils can be best employed in the fight against infections caused by bacteria from Acinetobacter genus as components of formulations for hygiene and disinfection of hospital environment.

The use of phytopharmaceuticals based on an investigated essential oil from thyme in the prevention and treatment of various human infections may be reasonable.

Strong antiseptic activity of essential oils has been known for a long time. The antibacterial activity of oils was tested against clinical bacterial strains of Staphylococcus, Enterococcus, Escherichia and Pseudomonas genera. The agar diffusion method was used for microbial growth inhibition at various concentrations of the oils from T. vulgaris and L. angustifolia. Susceptibility testing to antibiotics and chemotherapeutics was carried out using disc-diffusion method. 120 strains of bacteria isolated from patients with infections of oral cavity, respiratory, genitourinary tracts and from hospital environment were investigated. The results of experiments showed that the oil from T. vulgaris exhibited extremely strong activity against all of the clinical strains. Thyme oil demonstrated a good efficacy against antibiotics resistant strains of the tested bacteria. Lavender oil has been less activity against clinical strains of Staphylococcus, Enterococcus and Escherichia genus. The worst results have been observed against all strains of Pseudomonas aeruginosa.

Enterococci and streptococci were the most commonly isolated bacteria from root canals. The resistance of enterococci to many antimicrobials may pose a problem in their eradication.