Antibacterial activity of Vernonia amygdalina leaf extracts against multidrug resistant bacterial isolates
This study was undertaken to investigate the phytochemical and antibacterial activities of Vernonia amygdalina leaf extract against clinical isolates obtained from the University of Benin Teaching Hospital, using agar well diffusion method. Phytochemicals present in Vernonia amygdalin included flavonoids, cardiac glycosides, reducing sugar, terpenoids and saponins. Ethanolic extract acted against with inhibition zones ranging from 7.0±0.0mm at 25mg/ml to 14.5±2.5mm at 200mg/ml against E. coli; 6.5±0.5mm at 100mg/ml to 9.0±2.0mm at 200mg/ml against S. aureus; 11.0±1.0mm at 50mg/ml to 16.5±5.0mm at 200mg/ml; 7.5±1.5mm at 25mg/ml to 11.5±0.5mm at 200mg/ml. Inhibition zones in aqueous extract ranged from 8.0±2.0mm at 25mg/ml to 12.5±1.5 at 200mg/ml against P. aeruginosa; 9.0±1.0mm at 50mg/ml to 15.0±1.5mm at 200mg/ml against S aureus. The minimum inhibitory concentration of ethanolic extract ranged from 25mg/ml in S. aureus, P. aeruginosa, B. subtilis and K. pneumoniae to 50mg/ml in E. coli. Minimum bactericidal concentration of the ethanol extract was 50mg/ml in P. aeruginosa and K. pneumonia and 100mg/ml for E. coli, S. aureus and B. subtilis. MBC of 200mg/ml was observed for B. subtilis, S. aureus and P. aeruginosa in the aqueous fraction of the plant. The most antibiotic resistant bacterial strain was S. aureus (80%) while the least resistant was P. aeruginosa (10%). The most resistant bacterial strain was S. aureus (80%) while the least resistant was P. aeruginosa (10%). The most effective antibiotics were perfloxacin, ciprofloxacin, septrin and choramphenicol. Vernonia amygdalina extract was found to be more potent than conventional antibiotics.
Keywords: Antimicrobial, Phytochemical, Antibiotics, Susceptibility, Resistance