Inhibitory effect of onion juice and eucalyptus essential oil against antibiotic-resistant clinical isolates of Klebsiella pneumoniae and Escherichia coli

Background and Aim : Finding the right drug to treat bacterial infections has always been a challenge for researchers. This challenge has become more difficult due to the increasing development of bacterial resistance and the emergence of antibiotic-resistant strains. In this study, white onion juice (family: Amaryllidaceae) and eucalyptus essential oil (family: Eucalyptus) (Barij Esans Company, Iran) were tested against ۱۵ clinical isolates of Klebsiella pneumoniae and onion juice against ۶ clinical isolates of antibiotic-resistant Escherichia coli.Methods : Clinical isolates were previously identified using conventional biochemical tests and confirmed by polymerase chain reaction using ۱۶S rRNA gene primers. The pattern of sensitivity of isolates to onion juice and eucalyptus essential oil was determined by two methods of disk diffusion and the agar well diffusion, according to CLSI standards. Gentamicin antibiotic disc was used as positive control and sterile distilled water was used as a negative control. After ۲۴ hours of incubation at ۳۷ °C, the diameter of the bacterial growth inhibition zone was examined. The results of this study showed that eucalyptus essential oil had the highest growth inhibitory effect against K. pneumoniae isolates. Also, the growth inhibition of eucalyptus essential oil in the agar well diffusion method was higher than the disk method.Results : So that the growth inhibition zone of K. pneumoniae compared to eucalyptus essential oil was ۲۳ mm in the agar well diffusion method and ۹ mm in the disk diffusion method. All clinical isolates of K. pneumoniae and E. coli were resistant to the onion juice.Conclusion : According to the results of this study, it can be concluded that eucalyptus essential oil can be a suitable alternative to chemical drugs against K. pneumoniae as the herbal medicine with a high antimicrobial effect.

کلیدواژه ها:

Eucalyptus ، Onion ، Diffusion disk ، Antimicrobial activity