Antibacterial activity of the essential oil of Eucalyptus Grandis against ciprofloxacin resistant Staphylococcus Aureus and Ceftriaxone resistant Escherichia Coli

Abstract

The prevalence of antibiotic resistance among many of the known bacterial pathogens is more than ever before a looming worldwide concern as it undermines the efficacy of human medicine to treat bacterial infection patients, with the currently available antibiotics. Ceftriaxone and Ciprofloxacin, two famous antibiotics often used to treat Escherichia coli infections and Staphylococcus aureus infections respectively, are some of the antibiotics on the market whose ability to treat these infections is in jeopardy due to the prevalence of Ceftriaxone resistant E. coli and Ciprofloxacin resistant S. aureus. This has therefore set in motion a necessity to search for suitable medicinal plants with bioactive compounds with potent antimicrobial activity, for which the pathogenic microorganisms have not yet developed resistance. One of the potent remedies are plant essential or volatile oils, known to be rich in bioactive molecules. Members of the Eucalyptus genus have been found to be rich in essential oils with strong antimicrobial properties largely attributed to the oil constituent 1,8-cineole (Cineole or eucalyptol). In this study, the antibacterial activity of the essential oil extracted from the leaves of Eucalyptus grandis was tested against a Ceftriaxone resistant strain of E. coli and a Ciprofloxacin resistant strain of S. aureus; so as to test the potency of the oil in the fight to mitigate the problem of antibiotic resistance in human medicine, specific to this study for Ceftriaxone and Ciprofloxacin resistant bacteria pathogens. Antimicrobial susceptibility testing controls, Staphylococcus aureus NCTC 12981 and Escherichia coli NCTC 12241 were also used in the study to investigate the growth inhibitory effectiveness of the oil toward organisms which are known to have no resistance towards these antibiotics. Using well diffusion assay on Muller Hinton Agar, the growth inhibitory effect of the oil was tested on the organisms, and the results showed good antibacterial activities against all the four organisms used in the study. In light of the results from this study, it is therefore recommended that further pharmaceutical research and development be carried out on the medical potential of the essential oil of E. grandis and include it in modern antibiotic drug formulations.