Antimicrobial activity of Nigella sativa L. seed oil against multi-drug resistant Staphylococcus aureus isolated from diabetic wounds

Microbial resistance to existing antibiotics has led to an increase in the use of medicinal plants that show beneficial effects for various infectious diseases. The study evaluates the susceptibility of multidrug resistant Staphylococcus aureus to Nigella sativa oil. Staphylococcus aureus was isolated from 34 diabetic patient's wounds attending the Renaissance hospital, Nsukka, Southeast Nigeria. The isolates were characterized and identified using standard microbiological techniques. Isolates were cultured and a comparative In vitro antibiotic susceptibility test was carried out using the disk diffusion method. Of the 34 samples collected, 19(56%) showed multidrug resistance to the commonly used antibiotics. Nigella sativa oil was then studied for antibacterial activity against these multidrug resistant isolates of Staphylococcus aureus in varying concentration by well diffusion method. The oil showed pronounced dose dependent antibacterial activity against the isolates. Out of 19 isolates, 8(42%) were sensitive to undiluted oil sample; 4(21%) of these showed sensitivity at 200 mg/ml, 400 mg/ml and 800 mg/ml respectively. Eleven (58%) of the isolates were completely resistant to all the oil concentrations. The present study, reports the isolation of multi-drug resistant S. aureus from diabetic wounds and that more than half of isolates were susceptible to different concentrations N. sativa oil.