Antibacterial Activity of African and Asian Zingiberaceae Plant Species against Salmonella typhi
Katuura Esther *
Department of Plant Sciences, Microbiology and Biotechnology, School of Biological Sciences, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
Gerald Tumusiime
Department of Plant Sciences, Microbiology and Biotechnology, School of Biological Sciences, College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala, Uganda and Department of Bio-Molecular Resources and Bio-Lab Sciences, School of Bio-Security, Biotechnical and laboratory, College of Veterinary Medicine, Animal resources & Biosecurity, Makerere University, P.O. Box 7062, Kampala, Uganda.
*Author to whom correspondence should be addressed.
Abstract
Typhoid fever remains an important public health concern in many low- and middle-income settings, and increasing antimicrobial resistance has encouraged further investigation of plant-derived antibacterial agents. This preliminary in vitro study evaluated the antibacterial activity of ethanolic extracts of two Zingiberaceae species in Uganda, the introduced Zingiber officinale and the indigenous Aframomum angustifolium, against Salmonella typhimurium ATCC/3076, a close relative of Salmonella typhi. Rhizomes were extracted using ethanol. The crude extracts were tested using agar well diffusion, while minimum inhibitory concentration and minimum bactericidal concentration were assessed using serially diluted extracts. Ciprofloxacin was used as the positive control. A. angustifolium produced the highest mean inhibition zone of 33.0 ± 0.5 mm, compared with 30.3 ± 2.08 mm for ciprofloxacin and 17.0 ± 3.8 mm for the combined extract, while no bacterial inhibition was observed with Z. officinale. The lowest inhibitory concentrations observed for A. angustifolium and the combined extract were 0.125 g/ml and 0.250 g/ml, respectively. The minimum bactericidal concentration reported for A. angustifolium was 0.5 g/ml. These findings indicate that the ethanolic rhizome extract of A. angustifolium showed measurable in vitro antibacterial activity against the tested Salmonella strain, whereas Z. officinale did not show activity in this assay. Further studies are required to confirm the active constituents, reproducibility, and relevance against clinically confirmed S. Typhi isolates.
Keywords: African Zingiberaceae, Asian Zingiberaceae, Aframomum angustifolium, Zingiber officinale, Salmonella typhimurium, Salmonella typhi, antibacterial activity, ethanolic extract, minimum inhibitory concentration, minimum bactericidal concentration, typhoid fever, antimicrobial resistance