Antimicrobial Properties of Catha edulis (Miraa) against Select Bacterial and Fungal Pathogens, an in-vitro Experimental Study

Background: The increasing risk of emergence of antimicrobial resistance can be addressed by discovering alternatives to antibiotics such as plant-based botanicals. In the present study, the antimicrobial properties of aqueous and methanolic extracts of Catha edulis (Miraa) were tested on select pathogenic bacteria and fungi. Methods: Antimicrobial susceptibility tests were conducted in-vitro using the agar well diffusion method. The aqueous and methanolic extracts were dissolved in water to form 1000 mg/ml, 100 mg/ml, and 10 mg/ml doses. The antimicrobial susceptibility testing was done in appropriate culture media and conditions. Diameters of zones of inhibition were obtained, their means calculated, and t-tests applied to test significance of differences between means. Results: The aqueous Miraa extracts at all three concentrations significantly inhibited the growth of all bacterial pathogens except E. coli but did not have an effect on C. albicans . The largest zones of inhibition for the aqueous extracts were observed at 1000 mg/ml against S. pneumoniae (28.41 mm), S. pyogenes ATCC 19615 (24.27 mm), MRSA (21.86 mm), and S. aureus clinical isolate (20.38 mm). Similarly, the largest zones of inhibition for the methanolic extracts were at 1000 mg/ml against S. pneumoniae clinical isolate (26.75 mm), S. pyogenes ATCC 19615 (25.38 mm), S. aureus clinical isolate (19.71 mm), and MRSA ATCC 43300 (16.38 mm). Conclusions: Crude Miraa extracts have significant antimicrobial effects in vitro against the tested microorganisms. Further studies on Miraa extracts to identify the active phytochemicals and investigate their therapeutic effects in-vivo in animal models are indicated.