Antibacterial activity of zingiber officinale extract on common bacterial pathogens causing upper respiratory tract infections

Abstract

The ginger rhizome (Zingiber officinale) is known to be rich in secondary metabolites such as phenolic compounds, volatile sesquiterpenes and monoterpenoids. These specific phytochemicals and essential oils are responsible for the antimicrobial activity of ginger. However, there is limited information regarding the efficacy and efficiency of these herbal products. Therefore, this study aimed at determining the antibacterial activity of Zingiber officinale extracts on Pseudomonas aeruginosa, Streptococcus pneumoniae and Klebsiella pneumoniae, two bacterial organisms known to cause pneumonia in humans. An experimental study was conducted using aqueous and ethanolic extracts from ginger rhizomes collected from farms in Butambala, Mpigi district in central Uganda. Qualitative phytochemical screening tests were carried out. The alkaline reagent was used for Flavonoids, Dragendorff’s reagent was used for alkaloids and Iron (III) chloride was used for phenols. Agar well diffusion method was used for the evaluation of the antibacterial activity of Zingiber officinale. The extracts were found to have various quantities of phytochemicals including; Phenols, tannins, alkaloids, saponins, Terpenoids and Flavonoids. Overall, the ethanol extract showed better activity against all the bacteria than the aqueous extract. S. pneumoniae and P. aeruginosa had the lowest minimum inhibitory concentration of 0.0625 mg/ml and 0.125mg/ml for ethanol and aqueous extracts of Zingiber officinale with a 1.0 mg/ml minimum bactericidal concentration respectively. K. pneumoniae had the highest minimum inhibitory concentration of >2.0 mg/ml and 2.0 mg/ml for aqueous and ethanolic extracts respectively. There were significant differences between the activity of ginger ethanol extract and aqueous extracts against P. aeruginosa (P <0.05). The ginger extract was more effective than aqueous extract. Therefore, Zingiber officinale is a promising candidate for the formulation of drugs for the treatment of pneumonia.