Antimicrobial Activity of Nigella sativa Seeds Extracts Against Staphylococcus aureus Nasal Isolates among Sudan University of Science and Technology Students

Abstract

Nigella sativa has been used since ancient times as nutritional supplement and for the treatment of various infections and chronic ailments. Staphylococcus aureus is one of the important resistant pathogenic bacteria extremely adaptable to antibiotics pressure. It becomes a major health problem; so that use of new antimicrobial agents is the best choice to overcome this problem. This was a descriptive cross sectional study conducted in Khartoum State-Sudan, during the period from October to December 2017. The study aimed to determine the antibacterial activity of Nigella sativa seed. The methanolic and aqueous extracts obtained using maceration extraction. Both extracts were tested in varying dilutions against Staphylococcus aureus isolated from nasal carriers. The antibacterial effect of Nigella sativa was determined through cup-plate agar diffusion technique under standard laboratory conditions. One hundred nasal swabs were collected. 38/100(38%) showed bacterial growth. From which 11/38 (29%) S.aureus was isolated and identified using Gram stain, biochemical reactions and tested for their susceptibility to number of antibiotics. In this study percentage of S.aureus were found 7/38(64%) in males and 4/38(36%) in females .The results showed that 9% (1/11) of S. aureus isolates were resist to oxacillin while 91%(10/11) were resistant to amoxicillin. All strains were sensitive to Clindamycin, Vancomycin, and Fuscidin. Methanolic and aqueous extracts of Nigella sativa inhibits the growth of S.aureus dose dependently. A significant correlation was observed between zone of inhibition and concentration of extract this result confirm the antibacterial activity of Nigella sativa. The minimum inhibitory concentration of Nigella sativa methanol and water extracts obtained by agar diffusion method for S.aureus isolates was 12.5 mg/ml and 25 mg/ml respectively. In conclusion both Nigella sativa seeds aqueous and methanolic extract have activity against Staphylococcus aureus. This result authenticates the antibacterial activity of Nigella sativa seeds and support the traditional use of the plant in therapy of bacterial infection.