In vitro evaluation of antimicrobial potential of catha edulis on selected microorganisms

Abstract

To determine antimicrobial activity of Catha edulis on selected microorganisms and to determine the minimum inhibitory concentration of khat extracts as well as the establishment of the susceptibility of specific pathogens namely staphylococcus aureus, E. coli to Catha edulis crude extracts from three khat samples. The agar dilution method of the NCCLS (National Committee for Clinical Laboratories) was used to test the extracts at concentrations of 20-1.25 mg/ml, against 6 strains of microbes. MIC was defined as the lowest concentration at which there was no visible growth. Slight growth was defined as marked growth reduction (MGR). The agar dilution method was used to determine the MICs of the extracts and tetracycline which was used as the control. 55% of the strains were sensitive to the extracts (MICs 5-20mg/ml). Most. Streptococci were not sensitive. Lactobacillus fermentum was neither sensitive. The extracts were active against streptococcus pyogenes (MIC 10-20mg/ml) but not against Candida albicans, Staphylococcus aureus and Escherichia coli. Conclusion: Khat has water-soluble constituents possessing selective antibacterial activity against some oral bacteria. There is preliminary evidence for the presence of antibiotic resistance-modifying components.