Antibiotic resistant Salmonella is a major threat to poultry industry and public health. Medicinal plants are an effective alternative of antibiotics for the control and treatment of multiple drug resistant Salmonella. The objective of this study was to evaluate the in-vitro activity of essential oils of some medicinal plants against multiple drug resistant Salmonella of poultry origin and to determine their active ingredients. Essential oils of Cuminum cyminum, Cinnamomum zeylanicum, Eucalyptus globulus, Allium sativum and Nigella sativa were prepared by steam distillation and their active ingredients were determined by Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Activity of oils against Salmonella enteritidis (n=05) and Salmonella gallinarum (n=05) was determined by well diffusion assay. Broth microdilution assay was employed to determine the minimum inhibitory concentrations of oils. Well diffusion assay revealed that C. zeylanicum and E. globulus had better activity against salmonellae (26±7.6 mm and 16±6.8 mm, respectively) as compared to C. cyminum, A. sativum and N. sativa (8±5.9, 10±6.1, 8±4.7 mm, respectively). Minimum inhibitory concentrations of C. zeylanicum and E. globulus against Salmonella were 64.1±32.1 and 68.9±32.9 µg/mL, respectively. The GC-MS analysis revealed presence of diverse phytochemicals in all essential oils. Major antimicrobial phyto-constituents of essential oils of E. globulus and C. zeylanicum were eucalyptol (82.85%) and 1R-α-Pinene (13.781%), and cinnamaldehyde (64.14%) and eugenol (8.9%), respectively. It is concluded that essential oils of C. zeylanicum and E. globulus have excellent in vitro anti-Salmonella activity. It is insinuated that these extracts may be commercialized as an alternative of antibiotics for the control of Salmonellae in poultry after detailed in vivo evaluations.

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