The Combination Effect of Essential Oils and Ciprofloxacin on Staphylococcus aureus and Escherichia coli O157:H7 Isolated from Urinary Tract Infections

Abstract

     Antibiotics misused lead to the emergence of resistant isolates, making most drugs less effective. Therefore, several alternative antimicrobial compounds have been explored, such as essential oils from medicinal plants. Essential oils of two medicinal plants, Cupressus sempervirens and Eucalyptus, were used to evaluate their antibacterial effects with Ciprofloxacin against Staphylococcus aureus, as a Gram-positive bacterium, and Escherichia coli O157:H7, as a Gram-negative bacterium, that were obtained from an M.Sc. student in the biology department who isolated them from urinary tract infections. Identification of isolates was confirmed by some biochemical tests and the VITEK-2 Compact system. The toxicity effect of the essential oil of Cupressus sempervirens appears to have lower toxicity at 2500 ppm; its hemolysis per cent was 2.6%, while Eucalyptus essential oil was 100% at the same concentration. Cupressus sempervirens essential oil showed a higher antibacterial effect against E. coli with MIC=5000 ppm than Eucalyptus essential oil, which gave MIC=20000 ppm. All combinations of essential oils with Ciprofloxacin showed a synergistic effect, killing bacteria in all prepared concentrations. The essential oil of Cupressus sempervirens showed slightly lower activity against S. aureus, with the MIC of (10000 ppm), while Eucalyptus essential oil showed the same effect against E. coli. Generally, combinations showed slightly lower effects than those against E. coli.