Antibacterial activity of a traditional Ayurvedic polyherbal decoction against selected diarrheagenic and non-Diarrheagenic bacterial strains: An in vitro study

Munasinghe D.A.L.¹* and Fernando S.²

Abstract

Diarrhea and dysentery remain major public health concerns worldwide, particularly in developing countries. Increasing antimicrobial resistance among enteric pathogens has reduced the effectiveness of conventional antibiotics and necessitated exploration of alternative therapeutic options. Traditional Ayurvedic polyherbal decoctions (Kashaya) are widely used in the management of gastrointestinal infections; however, scientific validation of their combined antibacterial efficacy remains limited. The objective of this study was to evaluate the in vitro antibacterial activity of a traditional Ayurvedic decoction containing Plectranthus zeylanicus, Zingiber officinale, Piper longum, Syzygium aromaticum, and Trachyspermum ammi against selected diarrheagenic, dysentery, and nondiarrheagenic bacterial strains. A freshly prepared decoction was evaluated against ten bacterial strains (five diarrheagenic and five non-diarrheagenic) using the agar well diffusion method on Mueller–Hinton agar. Bacterial inocula were standardized to 0.5 McFarland turbidity. Plates were incubated at 37°C for 24 hours, and antibacterial activity was assessed by measuring zones of inhibition. The results revealed that the decoction exhibited antibacterial activity against eight of the ten tested organisms. Shigella sonnei, Shigella flexneri, Salmonella typhimurium, enteropathogenic Escherichia coli, Pseudomonas aeruginosa, Streptococcus saprophyticus, Enterococcus faecalis, and Streptococcus pneumoniae were sensitive. Staphylococcus aureus and enterotoxigenic Escherichia coli showed resistant. No zones of inhibition were observed in control plates. The findings provide scientific evidence supporting the traditional use of this Ayurvedic decoction in the management of diarrhea and dysentery. Further quantitative and in vivo studies are recommended to determine its clinical applicability.