Antibacterial activity of ethanolic and aqueous extracts of Zingiber officinale on Streptococcus pneumoniae and Pseudomonas aeruginosa

Background Streptococcus pneumoniae , a capsulated lancet gram-positive bacterium, is the leading cause of mortality and morbidity among children globally and is the primary cause of pneumonia. Pseudomonas aeruginosa is an opportunistic human pathogen and the leading cause of nosocomial infections, among patients who are admitted to intensive care units. With the increasing resistance of microorganisms to antibiotics, there is a shift of choice from allopathy to naturopathy, where herbs are common ingredients of medicines and components of treatment protocols. It is against this background that this study aimed to investigate the susceptibility of P. aeruginosa and S. pneumoniae to ethanolic and aqueous extracts of ginger using the agar well diffusion technique. Methodology Absolute (95%) Ethanol and distilled water were used as solvents to make extracts from the ginger powder. The filtrate was dried, and the resulting substance was used to conduct antimicrobial tests on Streptococcus pneumoniae and Pseudomonas aeruginosa isolates using the agar well diffusion technique. The diameters of inhibition zones were measured, and statistical analysis was done by one-way ANOVA. Minimum inhibitory and bactericidal concentrations were determined by serial dilution. Freshly prepared sterile distilled water was used as negative control and ciprofloxacin (5 μ g/disk), an antibiotic was used as positive control. Results The test organisms were sensitive to both ethanolic and aqueous extracts of ginger. However, this was highly dependent on the concentrations of the extracts. The ethanolic extract had lower Minimum Inhibitory and Bactericidal Concentrations than aqueous extract on both bacterial species and at a concentration of 2g/ml, the ethanolic extract was 2-fold and 1.6-fold more effective in inhibiting the growth of P. aeruginosa and S. pneumoniae respectively than aqueous extract. Conclusion With the high susceptibility of the tested bacterial isolates to the ginger extracts used in this study, it is evident that ginger extracts can serve as a suitable antibiotic. However, further studies need to be conducted on the antimicrobial effects of ginger extracts on other bacterial species. ### Competing Interest Statement The authors have declared no competing interest.