Antimicrobial activity of Cannabis sativa,Thuja orientalis and Psidium guajava leaf extracts against methicillin-resistant Staphylococcus aureus

Objective： This study examined the antimicrobial activity of Cannabis sativa, Thuja orientalis and Psidium guajava against methicillin-resistant Staphylococcus aureus （MRSA） and used a standardized purification protocol to determine the presence and abundance of bioactive compounds in the leaf extracts. Methods： In vitro antimicrobial activities of the ethanolic extracts of C sativa, T. orientalis and P. guajava were tested against MRSA. The presence of bioactive molecules in these three leaves was evaluated using biochemical assays and high-performance thin-layer chromatography （HPTLC）. Results： Resistance to methicillin, penicillin, oxacillin and cefoxitin was observed in each of the clinical and nonclinical MRSA isolates. However, they were still vulnerable to vancomydn. Used individually, the 50% extract of each plant leaf inhibited MRSA growth. A profound synergism was observed when C sativa was used in combination with T. orientalis （1：1 ） and when P. guajava was used in combination with T. orientalis （1：1 ）. This was shown by larger zones of inhibition. This synergism was probably due to the combined inhibitory effect of phenolics present in the leaf extracts （i.e., quercetin and gallic acid） and catechin, as detected by HPTLC. Conclusion： The leaf extracts of C sativa, T. orientalis and P. guajava had potential for the control of both hospital- and community-acquired MRSA. Moreover, the inhibitory effect was enhanced when extracts were used in combination.

Efficacy of Atmospheric Pressure Plasma as an Antibacterial Agent Against Enterococcus Faecalis in Vitro

Enterococcus faecalis （E. faecalis） is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofihn un- der different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus （S. aureus） was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively （P 〈 0.05）. The diameter was increased with prolongation of the treatment dura- tion. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm （P 〈 0.01）. The transmission electron microscopy revealed that the ultrastructural changes eytoderm of E. faecalis were observed after treatment for 2min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontie microbial treatment.