In vitro antimicrobial activity of plant fractions against major respiratory pathogens

From the ancient times, the use of plants is considered as a cure for many diseases and now, they are being used as a new resource for producing agents that could act as alternative to antibiotics. Current work was carried to investigate the antimicrobial potential of 42 different aqueous plant extracts and oils against Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa. In vitro antimicrobial activity of different concentrations (1.50mg/ml and 0.75mg/ml) of plant fractions was investigated against three clinical isolates: S. aureus, C. albicans and P. aeruginosa by agar well diffusion assay. Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs) were evaluated by broth dilution and plating method respectively. Among 42 plant fractions, methanol fractions of Cassia fistula leaves and flowers were active against S. aureus. Hexane fractions of Ixora coccinea stalk and leaves, methanol fractions of C. fistula flowers and chloroform fraction of C. fistula leaves were active against C. albicans. Methanol fractions of I. coccinea leaves and stalk were active against P. aeruginosa. The MICs of active fractions were found to be 0.45mg/ml and 0.6mg/ml for P. aeruginosa, S. aureus and C. albicans. The MBCs were found to be 1.50mg/ml for P. aeruginosa, 0.75mg/ml for S. aureus and 1.50mg/ml and 0.75mg/ml for C. albicans. In antibiotic susceptibility testing, all isolates were found to be sensitive to their respective antibiotics.