Antibacterial Activities of Ethanolic and Aqueous Extracts of Vernonia amygdalina (bitter leaf) with Ciprofloxacin on Selected Bacteria

Abstract

Vernonia amygdalina, commonly known as bitter leaf, is a widely grown plant in Africa that has several health benefits. This study aimed  to compare the antibacterial activities of ciprofloxacin with those of ethanolic and aqueous extracts of Vernonia amygdalina (bitter leaf)  on selected bacteria. Swabs were collected from patients presenting with bacterial conjunctivitis at the Eye Clinic, Department of  Optometry, Federal University of Technology, Owerri. The samples were transported to the Microbiology Laboratory at the Federal University Teaching Hospital, Owerri, for culturing and identification of microorganisms using standard microbiological methods. The  zones of inhibition of ciprofloxacin on selected bacteria isolated from the swab samples were compared with those of the ethanolic and  aqueous extracts of Vernonia amygdalina. Four bacteria were isolated from the samples: Staphylococcus aureus, Escherichia coli,  Klebsiella pneumoniae and Streptococcus pyogenes. At concentrations of 100, 50, 25 and 12.5 mg/ml respectively, there were significant differences (p˂0.05) in the zones of inhibition between ciprofloxacin and the ethanolic and aqueous extracts against S. aureus, E. coli, K.  pneumoniae and S. pyogenes. With 12.5 mg/ml concentration, the extracts showed no significant differences (p>0.05) in the zone of  inhibition. Ciprofloxacin showed significantly higher (p˂0.05) zones of inhibition, followed by Vernonia amygdalina ethanolic extract  (p˂0.05) and Vernonia amygdalina aqueous extract (p˂0.05). The zones of inhibition produced by Vernonia amygdalina ethanolic extract  on both grampositive and gram-negative bacteria highlight its antibacterial effect and its potential as an alternative treatment option for  bacterial infections.