Abstract :
Antibiotic resistance is developing fast, hampering the efficacy of the already available antibiotics. Nerium oleander is a well-known traditional plant that has many applications in folk medicine as it is rich in bioactive compounds with multiple pharmacological effects. This study was carried out to assess the antibacterial potential of crude Nerium oleander leaf extract (NOLE) against different pathogens and also the synergistic interaction between NOLE and ceftriaxone. The antibacterial activity of NOLE was assessed against Gram-negative (Escherichia coli and Pseudomonas aeruginosa), Gram-positive (Bacillus subtilis and Listeria monocytogenes), and multidrug resistant pathogens (methicillin-resistant staphylococcus aureus and Klebsiella pneumonia) using the agar well diffusion assay. Possible synergism between NOLE and ceftriaxone was evaluated against MRSA using the checkerboard method. The phenol content of the hydro-ethanol extract of NOLE was found to be 72.1 mg/g. Crude NOLE was highly effective and inhibited the growth of all the tested pathogens. Gram-positive bacteria were more susceptible to NOLE than Gram-negative bacteria. The largest inhibition zone (42 mm) was found to be exhibited against B. subtilis. NOLE was effective against MRSA and MDR K. pneumonia when compared to ceftriaxone. The minimum inhibitory concentration (MIC) value of the extract was the lowest (12.5 µg/mL) against E. coli and L. monocytogenes and the highest (200 µg/mL) against MRSA. A synergism was recorded between NOLE and ceftriaxone against MRSA. It is concluded that crude leaves extract of N. oleander is a potent antibacterial and can be combined with antibiotics to enhance their efficacy.
