EFFECTS OF CRUDE ALKALOID EXTRACTED FROM OCIMUM GRATISSIMUM ON THE ACTIVITY OF CIPROFLOXACIN AGAINST SALMONELLA ENTERICA SEROVAR TYPHI

Salmonella infection has been a major food-borne infection in Nigeria, and proliferations of multi-drug resistant strains of Salmonella possess a threat to public health. This work was carried out to investigate the effect of crude alkaloid extracted from Ocimum gratissimum leaf on the activity of ciprofloxacin against Salmonella enterica serovar Typhi. An egg white was aseptically collected from raw egg and plated on Salmonella Shigella agar (SSA) using pour plating method and incubated at 37°C for 24 h. Crude alkaloid was extracted from Ocimum gratissimum using solvent extraction method. Agar-well diffusion technique was used to evaluate the antibacterial activity of the alkaloid and in combination with ciprofloxacin against Salmonella enterica serovarTyphi. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined using double-fold serial dilution technique at concentrations 25 mg/ml to 400 mg/ml. The results revealed that the crude alkaloid (16.70 mm) and Ciprofloxacin (23.33 mm) showed a pronounced inhibitory effect on the test organism. An antagonistic activity existed between the alkaloid and ciprofloxacin as zones of inhibition decreased to 27.33 mm. The results of the MICs and MBCs showed the inhibitory substances had significant inhibitory and cidal activities. The research further revealed that the crude alkaloid possesses antibacterial properties, so single dose of the crude alkaloid or the ciprofloxacin should be administered separately when managing Salmonella infections. Synergistic effects existed between the crude alkaloid in an increased concentrations (100, 150, 200,250,300 and 350mg/ml) with ciprofloxacin in a decreased concentrations (350,300,250,200,150 and 100mg/ml), of which equal volumes of the test substances at 200mg/ml each proved to be most effective against the test organism. The test substances at concentrations ≤ 50 mg/ml showed additive effects. This research has shown that the combined use of crude alkaloid and ciprofloxacin showed remarkable synergic effect against Salmonella enterica serovar Typhi, of which the combination of equal volume from 200 mg/ml of each substanceproved to be more effective. Key words: Salmonella enterica serovar Typhi, crude alkaloid, Ocimum gratissimum, ciprofloxaci