Phytochemical screening and antimicrobial efficacy of Ocimum sanctum (Tulsi) and Swertia chirayita (Chirota) against Escherichia coli and Salmonella spp. isolated from poultry and their molecular study

Abstract

The present study was conducted to evaluate the effect of ethanolic extract of Tulsi and Chirota against Salmonella spp., Staphylococcus aureus and E. coli and isolation of plasmid from antimicrobial resistant bacteria from June 2020 to September 2021 at Chittagong Veterinary Animal Science University (CVASU), Bangladesh. Tulsi and Chirota were collected from a local market in Chattogram. Then both Tulsi and Chirota were then immersed in Ethanol (70%) for 3-time: 7 days, 14 days, and 21 days. After 21 days, all three batches of Tulsi and Chirota were conducted phytochemical screening for proven the presence of secondary metabolites such as alkaloids, flavonoids, saponins, tannins, phenolic compound, glycosides, carbohydrates, reducing sugar, protein and amino acid, acidic compound, phytosterol, steroids and terpenes. And further investigate the efficacy of ethanolic extract of Ocimum sanctum (tulsi) along with some other commercial antimicrobial including ciprofloxacin, amoxicillin, enrofloxacin, colistin and sulfamethoxazole. Three different concentrations of 0.2 mg/μL, 0.3 mg/μL and 0.4 mg/μL ethanolic plant extracts were treated against E. coli, Salmonella spp. isolated from poultry and commercially isolated Staphylococcus aureus. Ocimum sanctum extracts showed zone of inhibition at 0.2 mg/μl 14 days extract against E. coli (7-9mm), Salmonella spp. (17-19mm) and Staphylococcus aureus (14-15mm), which is similar to the intermediary zone sensitivity of ciprofloxacin, sulfamethoxazole and amoxicillin. Within commercial antibiotics, ciprofloxacin, amoxicillin, enrofloxacin and sulfamethoxazole were 100% sensitive, whereas colistin were found to be 100% resistant. After that, plasmid isolation was done to observe the plasmid in those resistant bacteria. It was found that plasmid was present in the resistance bacteria that inhibited the activity of Tulsi. In summary, Tulsi ethanolic extract showed antimicrobial efficacy against E. coli, Salmonella spp. and Staphylococcus aureus which can be used as a substitute of commercial antibiotics.