Antibacterial effects of the aqueous extract of Lycopersicon esculentum mill native in South Khorasan of Iran against four species associated with gastrointestinal infections

Introduction: Raising antibiotic resistance has led the human community to more frequent application of herbal medicines. The tomato fruit, scientifically called Lycopersicon esculentum mill, is an important source of vitamins, minerals, and antioxidants, all with beneficial effects on human health. The present study aimed to evaluate the antibacterial effects of tomato aqueous extract on four important bacterial species associated with gastrointestinal infections. Materials and methods: After preparing the aqueous extract of native tomato, its minimum inhibitory concentration (MIC) was determined against Staphylococcus aureus (S. aureus) (ATCC116538), Klebsiella pneumonia (K. pneumonia) (ATCC700603), Shigella flexneri (S. flexneri) (ATCC12022), and Proteus vulgaris (ATCC6380) species using the microdilution broth method based on the Clinical and Laboratory Standards Institute (CLSI) guidelines. Each of the experiments was repeated three times. One-way Analysis of Variance (ANOVA) was used for examining normal variables. Results: The results of this study showed that the most significant effect of the tomato extract is on S. aureus. The MIC of tomato extract for S. aureus was 31.25 mg/ml, while for Proteus vulgaris, K. pneumoniae, and S. flexneri was 62.5 mg/ml. The mean MIC of the extract was significantly different between the studied bacteria (P < 0.05). Conclusion: The current study revealed a relatively significant antibacterial effect of tomato extract against different bacterial species and more studies are needed in this area