Protective effect of cinnamaldehyde on channel catfish infected by drug-resistant Aeromonas hydrophila

The protective effect of cinnamaldehyde on channel catfish infected by drug-resistant Aeromonas hydrophila CW strain was explored by observing the clinical signs and histopathology, measuring the cumulative mortality, serum biochemical and non-specific immune indicators, and intestinal microbiota in this study. The cumulative survival rate of the cinnamaldehyde within 14 days was significantly higher than that of the challenge group, which was 70% and 20%, respectively. Compared with the challenge group, the activities of lysozyme, superoxide dismutase, and glutathione peroxidase in the treatment group were increased, while there was no significant difference in catalase activity. Compared with the challenge group, the histopathology results showed that the injury of liver, spleen, and kidney was significantly alleviated after cinnamaldehyde treatment. The results of intestinal microbiota showed that the proportion of Proteobacteria in the challenge group was significantly increased, and the proportion of Aeromonas sp. reached 30% based on the analysis of species classification level. The composition of dominant species in the treatment group was similar to the control group. In conclusion, cinnamaldehyde increased the cumulative survival rate of channel catfish infected by A. hydrophila. It could protect channel catfish through improving the non-specific immune function of channel catfish, alleviating the pathological lesions of liver, spleen, kidney, and intestine, and maintaining the relative balance of the intestinal microbiota. Therefore, cinnamaldehyde could be a candidate drug for the treatment of A. hydrophila infection.