Effect of Formic Acid as Feed Additive on Histopathological Changes Induced by Aeromonas Hydrophila in Oreochromis Niloticus.

The purpose of this study was to determine whether Aeromonas hydrophila possesses several antibiotic resistance genes, such as BlaTEM, qnrS, blaSHV, TetA(A), NDM-1, and Mcr1. Additionally, the impact of adding a formic acid dietary supplement on recovery of histopathological changes of Nile tilapia (Oreochromis niloticus) infected with Aeromonas hydrophila. Before the beginning of the experiment, ten of the approximately 110 tilapias (50±3 g) were checked to make sure they were free from A. hydrophila. The remaining 100 tilapias were then randomly distributed into four experimental groups, G1: negative control; without any dietary supplement. G2: positive control; at the day 45 challenged with IP injection with (0.2ml of 1x105 CFU/ fish) of A.hydrophila. G3: Nile tilapias were fed a prepared ration with dietary supplementation of 0.3% formic acid for 45 days. G4: Nile tilapias were fed a prepared ration with dietary supplementation of 0.3% formic acid for 45 days then challenged with IP injection with (0.2ml of 1x105 CFU/ fish) of A.hydrophila. After 45 days of feeding trials, histopathological alterations revealed the appearance of normal structure of hepatic, renal and splenic tissue for G3 and G4 respectively than the control groups. In conclusion, formic acid may be a useful dietary supplement for improving health status and pathological alteration induced by Aeromonas hydrophila.