ANTIMICROBIAL SUSCEPTIBILITY OF CRUDE EXTRACTS OF Allium ascalonicum LINN. (WHOLE PLANT) AND Gladiolus psittacinus HOOK (CORM) AGAINST FIVE COMMON PATHOGENS: AN IN VITRO INVESTIGATION

Allium ascalonicum Linn. and Gladiolus psittacinus Hook., are two important plants cultivated across the world for their nutritional as well as medicinal values. In the quest for a more natural bioactive substance to check the rising incidence of antimicrobial resistance amongst pathogens, these two plants were in this study, screened for activity against five common pathogens; namely, Staphylococcus aure- us ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 35657, and Candida albicans ATCC 90029. Phytochemical screening carried out on the extracts showed the presence of secondary metabolites like saponins, cardiac glycoside, alkaloids and flavonoids in both plant samples but only Allium ascalonicum yielded essential oil, while carbohydrate and tannins were detected in Gladiolus psittacinus. While the crude extracts of Gladiolus psittacinus did not show any inhibitory potential against any of the tested organisms, three pathogens were susceptible to Allium ascalonicum, with minimum inhibitory concentration (MIC) of 100 mg/mL. Bactericidal kinetics studies on the three pathogens showed that within the exposure time of 4 hours, the organisms were killed (69% and 95% at 2 × MIC and 4 × MIC, respectively) , a result which compared well with the positive control Gentamicin. The result of this study while agreeing with earlier reports on the non-activity of Gladiolus corms against Candida albicans contradicts the same report on the activity of the crude extract of this plant against Pseudomonas aeruginosa. The significant inhibitory potential of the crude methanolic extract of Alli- um ascalonicum against food borne pathogens such as Staphylococcus aureus, Escherichia coli and nosocomial pathogen such as Klebsiella pneumoniae, suggests that it can be explored as a natural alternative to chemical preservatives in food industries, and in the formulation of drugs against nosocomial infections .