Abstract:
The in vitro antibacterial activity of methanolic and ethyl acetate leaf extracts of Ocimum gratissimum and Byrsocarpus coccineus on Methicillin Resistant Staphylococcus aureus (MRSA) was evaluated. Ocimum gratissimum is an aromatic medicinal plant belonging to the family Lamiaceae while Byrsocarpus coccineus Schum and Thonn. (Connaraceae), a scandent shrub widely dispersed in tropical Africa. They are widely used in ethnomedicine for the treatment of diverse ailments. Crude leaf extracts of Ocimum gratissimum and Byrsocarpus coccineus were obtained using soxhlet extraction with methanol and ethyl acetate. Ten clinical isolates of MRSA were obtained from wound, high vaginal, nasal, sputum and urine samples. The antibacterial activity of the extracts was investigated using agar well diffusion and macro-broth dilution methods, while molecular techniques were used for plasmid isolation and curing. Ethyl acetate leaf extract of Ocimum gratissimum, exhibited no zone of inhibition in all the MRSA isolates from wound, high vaginal, nasal, sputum and urine samples. The activity of the methanolic extracts of Ocimum gratissimum was concentration dependent, ranging from 7-14mm, with minimum inhibitory concentration (MIC) of 31.25-125mg/ml, and minimum bactericidal concentration (MBC) from 62.5-125mg/ml. Methanolic and Ethyl acetate leaf extracts of Byrsocarpus coccineus exhibited antibacterial activity ranging from 10-17mm and 7-13mm respectively. The MIC for methanolic extract of Byrsocarpus coccineus was 15.62mg/ml, while the MBC ranged from 31.25-62.5mg/ml. The MIC for ethyl acetate extract of Byrsocarpus coccineus ranged from 31.25 -125mg/ml, while the MBC ranged from 62.5-500mg/ml. Only the plasmid isolated from wound swab MRSA with molecular weight of 23130bp, was cured with 125ug/ml of acridine orange. The study underscores the higher antibacterial activity of the methanolic leaf extract of Byrsocarpus coccineus, and its potential for use in the management of MRSA infections.
