The Effect of Aqueous and Ethanolic Extracts of <i>Nannorrhops ritchiana</i> Fruit on Pathogenic Bacteria <i>Aeromonas hydrophila</i>, <i>Yersinia rockeri</i> and <i>Streptococcus iniae</i> in Rainbow T

Background: The excessive use of antibiotics to treat bacterial diseases in aquaculture has led to drug resistance in bacterial strains, reduced the effectiveness of drugs, and caused the accumulation of antibiotics in the bodies of fish and fish consumers. Objectives: The present study aimed to investigate the effect of aqueous and ethanolic extracts of the fruit of Nannorrhops ritchiana on the pathogenic bacteria Aeromonas hydrophila, Yersinia ruckeri, and Streptococcus iniae in rainbow trout. Methods: Bacterial strains were prepared as standard. To determine the minimum inhibitory concentration (MIC) of aqueous and ethanolic extracts, the standard microdilution method was used, and the minimum bactericidal concentration (MBC) of the extracts was obtained based on their MIC values. Results: The results of this study showed that the MIC of the ethanolic extract against A. hydrophila, Y. ruckeri, and S. iniae was 1.56, 6.25, and 0.78 μg/mL, respectively. In contrast, the MIC of the aqueous extract of N. ritchiana against these bacteria was 1.25, 25, and 6.25 μg/mL, respectively. Conclusions: The results of the study demonstrated that the extract of the N. ritchiana plant has a very high inhibitory effect against fish pathogenic bacteria, suggesting that this plant can be used to treat and reduce infections.