Document Type : Original Article
Authors
1
Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Bahonar University of Kerman, Kerman, Iran
2
Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran
Abstract
The widespread use of antibiotics in agriculture, aquaculture, and medicine has led to the environmental dispersion of these compounds and the rise of drug-resistant bacterial pathogens. To prevent antibiotic resistance, employing herbal extracts and essential oils against pathogenic bacteria is a promising strategy. This study evaluated the antimicrobial efficacy of plant extracts from Trachyspermum ammi (T. ammi) and Stachys lavandulifolia (S. lavandulifolia) against Lactococcus garvieae (L. garvieae) using the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and disc diffusion test. Results showd that the ethanolic extract of T. ammi showed inhibition zones ranging from 22.06 mm to 0 mm, with an MBC of 18.75 mg/mL, while the aqueous extract ranged from 18.2 mm to 0 mm, with an MBC of 75 mg/mL. For comparison, the inhibition zones for streptomycin, erythromycin, and gentamicin were 21.75, 20.7, and 18 mm for the ethanolic extract and 21.32, 19.9, and 18.5 mm for the aqueous extract, respectively. In the case of S. lavandulifolia, the ethanolic extract exhibited inhibition zones ranging from 17.2 mm to 0 mm, with an MBC of 75 mg/mL, while the aqueous extract ranged from 16.6 mm to 0 mm, also with an MBC of 75 mg/mL. The inhibition zones for streptomycin, erythromycin, and gentamicin were 22.3, 18.9, and 18.1 mm for the ethanolic extract and 21.8, 20.2, and 17.9 mm for the aqueous extract, respectively. In conclusion, both T. ammi and S. lavandulifolia possess significant antimicrobial activity against L. garvieae, particularly at higher concentrations. Ethanolic extracts generally demonstrated greater efficacy compared to aqueous extracts, suggesting ethanol as a more effective solvent for extracting antimicrobial compounds. These findings support the potential use of these plant extracts as alternative treatments in aquaculture to combat bacterial infections and reduce reliance on traditional antibiotics, thereby mitigating the risk of antibiotic resistance
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