Barugahara Evyline Isingoma^{1, 2,}, Mbugua Samuel¹, Karuri Edward¹

The antimicrobial properties and nutrient content of Moringa oleifera leaves have made them of great interest in current scientific research. This study determined the Minimum Inhibition Concentration of Moringa oleifera leaf powders against some common diarrhoea causing bacteria. Four bacterial strains of Escherichia coli, Salmonella typhi, Shigella shiga and Staphylococcus aureaus were used in the study. Moringa oleifera leaves powders were thoroughly mixed with sterile Brain Heart Infusion (BHI) broth and centrifuged for 15minutes before being strained using a filter paper. Ten millilitres of sterilized BHI with different levels of moringa leaf powders were each inoculated with 0.05 millilitres of standardised suspension of tested bacteria. Sterilized BHI alone and BHI with varying levels of moringa leaf powder without the pathogens were also prepared to be used in standardising the spectrophotometer. Readings were taken before and after incubating the different samples and bacterial growth was tested by measuring optical density in the broth at 600 nm after incubation for 24 hours at 35°C. The difference in spectrophotometer readings before and after incubation of the samples was used to indicate growth of bacterial pathogens. Results indicated that Moringa oleifera leaf powders inhibited growth in all the four bacterial strains due to its antimicrobial properties. The minimum inhibition concentration of Moringa oleifera leaf powder against 0.05 millilitres of standardised Escherichia coli varied between 8.4g to 9.8g of moringa oleifera leaf powder per 100 millilitres of BHI broth while for Staphylococcus aureaus it ranged between 9.8g to 10.2g Moringa oleifera leaf powder per 100mls of BHI broth. The results of this investigation can be used to guide low income households and pharmacists on the quantities of dried M. oleifera leaf powder to use in an effort to eliminate diarrhoea due to E. coli and S. aureaus pathogens.

Minimum inhibition concentration, Antimicrobial properties, Moringa oleifera leaves, Diarrhoea causing pathogens