Abstract
Antibiotic treatment is the main therapeutic option in western medicine to help combat bacterial infections. Over the years, bacteria have become resistant to these antibiotic agents. Antibiotic resistance can lead to an increase in mortality and morbidity rate. The need for novel therapeutic options for the treatment of bacterial infections is immediate. The aim of this project was to ascertain the antimicrobial activity of Nigella sativa L. seed oil on Escherichia coli (E. coli) reference strains. E. coli is among the most common causes of bacterial infections worldwide and has become resistant to many classes of antibiotics. Nigella sativa L. seed oil have a long history of folklore usage as medicine in the treatment of a variety of illnesses related to the respiratory system, digestive tract, kidney and liver functions etc. This study was done on 33 E. coli reference strains using Kirby-Bauer Disk Diffusion Method and Minimum Inhibitory Concentration method. For these experiments, cold pressed Nigella sativa L. seed oil was tested against the E. coli strains in its pure form as well as in its emulsified form. Using Kirby-Bauer Disk method, zones of inhibition were measured in milimeters and to confirm antimicrobial activity, Minimum Inhibitory Concentration method was used to determine the lowest concentration of Nigella sativa L. seed oil needed to inhibit E.coli. Upon using Kirby-Bauer Disk Diffusion Method, Nigella sativa L. seed oil showed growth inhibition of 13 E. coli reference strains with an average diameter of 7.2mm. When mixed with Tween 80 only, one strain was susceptible to the oil with an average diameter of 6.21mm. On using Minimum Inhibitory Concentration method, Nigella sativa L. seed oil showed no antimicrobial effects in all reference strains. The conclusion that can be drawn is that the antimicrobial activity of Nigella sativa L. seed oil tested with the current method did not show antimicrobial effects against E. coli in-vitro. It could be due to the low oil concentration used that could have also reduced the effectiveness, especially when tested in liquid culture. As can be observed from the literature, there are no standardised methods or solvents and therefore this supports the need to develop a standardised method for testing antimicrobial oils in-vitro.
M.Tech. (Complementary Medicine)