Evaluation of the Antibacterial Activity of Clove Extract (Syzygium aromaticum) on Clinical Isolates of Staphylococcus aureus

Abstract

Antibiotic resistance to conventional antibiotics has remained a significant therapeutic challenge in clinical settings. To this end, alternative therapeutic approaches are being sought after. One such approach is the use of antimicrobial inhibitors derived from natural sources, such as medicinal plants. S. aromaticum contains phenylpropene eugenol, which gives it its strong characteristic aroma. This component also demonstrates broad antimicrobial activity against Gram-positive, Gram-negative, and Acid-fast bacteria, as well as antifungal properties. Flavonoids in S. aromaticum contribute to various cellular defence mechanisms, acting against different inflammatory mediators and free radical species. This study aimed to explore the antibacterial potential of aqueous and ethanolic extracts of Clove (Syzygium aromaticum) against Staphylococcus aureus isolated from clinical sources in Port Harcourt, Nigeria. The antibacterial activity of S. aromaticum extracts against S. aureus was determined in vitro in aqueous and ethanolic extracts at four different extract concentrations: 200mg/ml, 100mg/ml, 50mg/ml, 25mg/ml and 12.5mg/ml. Analysis of phytoconstituents revealed the presence of Flavonoid, Saponins, Alkaloids and Eugenol. The aqueous and ethanolic extracts revealed a significant degree of antibacterial activity against S. aureus isolates at concentrations of 200mg/ml with zones of inhibition of 24mm and 28mm, respectively. Minimum Inhibitory Concentration (MIC) for the aqueous and ethanolic extract was at a concentration of 200mg/ml, and the Minimum Bactericidal Concentration (MBC) for aqueous and ethanolic extract was also at a concentration of 200 mg/ml. Antibiotic susceptibility testing revealed that S. aureus was susceptible to Ciprofloxacin. The independent T-test analysis revealed no significant difference in the diameter of the inhibition zone between the aqueous and ethanolic extracts of cloves (P = 0.640). Notably, the antibacterial activity of S. aromaticum extract was comparable to that of Ciprofloxacin because the zone of inhibition was at par with those observed with the ethanolic extract. This study suggests that S. aromaticum extract may be a promising natural antibacterial agent for combating S. aureus infections at high concentrations. Based on the results, further research is recommended using even higher concentrations of the extract and various extract media such as methanol, chloroform, and acetone to observe and compare their inhibitory effects on S. aureus.