Survey the synergistic effect of the cotrimoxazole and Nigella sativa extract on methicillin resistant Staphylococcus aureus bacteria

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important pathogens causes of hospital infections in the world, which has become resistant to many common antibiotics. Increasing antibiotic resistance in bacteria has increased attention to herbal medicines and natural antimicrobial substances. Due to its metabolites such as thymoquinone, Nigella sativa has various effects, including antibacterial properties. This research was conducted to determine the antibacterial effect of Nigella sativa extract and the cotrimoxazole, as well as the combined effect of these two substances on the standard MRSA strain in laboratory conditions.

In this study antimicrobial effects of Nigella sativa extract and cotrimoxazole separately and together using the checkerboard method on MRSA (ATCC33591) standard strain were investigated by microdilution method and their minimum growth inhibitory concentration (MIC) were determined.

Cotrimoxazole antibiotic at MIC of 5 μg/ml and Nigella sativa extract at 4.687 mg/ml prevented the growth of the target bacteria. When combining both of them were tested, the MIC concentration for both extract and antibiotic combinations was significantly reduced. These values ​​were reduced to 0.292 mg/ml for the extract and 2 μg/ml for the antibiotic.

According to the obtained results, the antibacterial activity of Nigella sativa ethanolic extract and cotrimoxazole have a synergistic effect on MRSA. Thus, we can use the combination both of antibacterial agents for improving the antimicrobial effect.