In-vitro antibacterial activity of cinnamon bark extracts on clinical multi-drug resistant (mdr) Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa isolates

The present study was conducted to investigate antimicrobial activity of ethanol, dichloromethane and n-hexane extracts of Cinnamomum verum stem bark against Multi-drug resistant clinical isolates. C. verum bark powder was extracted with ethanol, dichloromethane and hexane respectively using Soxhlet extractor for 6 hrs. at temperature not exceeding the boiling point of the respective solvents. The extracts were further subjected to phytochemical screening as well as antimicrobial tests against clinical isolates of confirmed multi-drug resistant Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa using agar well diffusion method. Minimum inhibitory concentrations (MICs) and Minimum bactericidal concentrations (MBCs) were also determined. The extracts yield 11.8g, 10.2g and 9.0g for ethanol, dichloromethane and hexane respectively. The results of phytochemical screening indicated the presence of alkaloids, reducing sugars, saponins, steroids, cardiac glycoside, flavonoid, anthraquinones and tannins in the extracts. The ethanolic extracts showed the highest antimicrobial activity of 12.3±0.5mm against P. aeruginosa and 15.3±1.3mm against K. pneumoniae at 100mg/ml and antibacterial activities of 11.3±0.5mm against K. pneumoniae followed by 9.0±0.4mm against Pseudomonas aeruginosa and the least 8.0±0.0mm against Staphylococcus aureus at 20mg/ml concentration. While hexane extract of the plant has the highest activity of 9.0±0.0mm against Staphylococcus aureus isolates but less active against the remaining isolates at 20mg/ml concentration. Dichloromethane extract was less active against all the MDR isolates. The results showed that the MICs of C. verum ranged from 5-20 mg/ml while the MBCs ranged from 10-40 mg/ml. Thus C. verum could be used as potential source of antibacterial agents against MDR microbes.