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ABSTRACTAeromonas hydrophila(A. hydrophila) can cause a number of diseases in both human and animals. A. hydrophila-related infections in aquaculture cause severe economic losses every year throughout the world. The emergence of antibiotic resistance that is due to the abuse of antibiotics has limited the application of antibiotics. Thus, novel approaches are needed to combat with treatment failure of antibiotics caused by resistant bacterial strains. Aerolysin plays a critical role in the pathogenesis of A. hydrophilaand has been considered as a novel target for developing drugs based on anti-virulence strategies. Here, we reported that luteolin, a natural product with no anti-A. hydrophilaactivity, could reduce aerolysin-induced hemolysis by inhibiting aerolysin activity. The binding mode was simulated by molecular docking and dynamics simulation. Then the main binding sites were confirmed by fluorescence quenching assays. We found that luteolin could hindered the formation of functional heptamer of aerolysin according to the results of the oligomerization assay. Moreover, luteolin could protect A549 cells from aerolysin mediated cell death and increase the survival rate of A. hydrophila-infected channel catfish. These findings suggest a novel approach to developing drugs fighting against A. hydrophila, and luteolin can be a promising drug candidate for treatment of A. hydrophila-associated infections.

•Enterobacter cloacaeis a novel bacterial pathogen that responsible for the infections of crayfish.•This is the first report of multi-resistant E. cloacaestrain isolated from disease crayfish.•The results provided in the study indicated that carbapenem-resistant genes have been spread in aquaculture.