In Vitro Antibacterial Potential of Salix babylonica Extract against Bacteria that Affect Oncorhynchus mykiss and Oreochromis spp.

SIMPLE SUMMARY: Aquaculture development is limited by several diseases associated with bacteria that have developed resistance to antibiotics. In this context, new treatment alternatives are necessary. The aim of the present study was to evaluate the in vitro antibacterial effects of Salix babylonica hydro-alcoholic extract against some bacteria that affect rainbow trout (Oncorhynchus mykiss) and tilapia (Oreochromis spp.). The results indicate that Salix babylonica hydro-alcoholic extract has an antibacterial effect and could be an alternative treatment in diseases caused by microorganisms resistant to drugs in aquaculture. ABSTRACT: Aquaculture development is limited by bacteria associated with several diseases; antibiotics are used for the treatment of these affections, but bacteria have developed resistance to these drugs. It is important to develop effective treatments that allow the production of antibiotic-free food. The aim of the present study is to evaluate the in vitro antibacterial effects of Salix babylonica hydro-alcoholic extract (SbHE) against Aeromonas hydrophila, Listonella anguillarum, Edwarsiella tarda, and Streptococcus iniae, bacteria that affect Oncorhynchus mykiss and Oreochromis spp. production. SbHE was obtained through the maceration technique. Reference strains were used and their sensitivity to antibiotics was determined. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of SbHE were determined. Results showed that three of four evaluated bacteria were multidrug resistant, except S. iniae. SbHE showed antibacterial activity against all bacteria. Results indicate an MIC of 1.56 to 25 mg/mL and an MBC of 3.12 to 100 mg/mL. The greatest inhibitory activity occurred against L. anguillarum obtaining a MIC of 1.56 mg/mL and an MBC of 3.12 mg/mL. Results indicate that SbHE has bactericidal activity against A. hydrophila, L. anguilalurm, and S. iniae as well as bacteriostatic activity against E. tarda and could be an alternative treatment against these bacteria.