Effects of combined florfenicol and chlorogenic acid to treat acute hepatopancreatic necrosis disease in Litopenaeus vannamei caused by Vibrio parahaemolyticus

We evaluated the survival, disease resistance, and immunity of Litopenaeus vannamei infected with Vibrio parahaemolyticus causing acute hepatopancreatic necrosis syndrome (VPAHPND), and treated with florfenicol (FFC) and chlorogenic acid (CGA), alone or in combination. Following VPAHPND challenge, the shrimps were fed a drug-free diet (control), or FFC (15 mg.kg(-1)), CGA (200 mg.kg(-1)), low-dose drug combination (100 mg.kg(-1) CGA + 7.5 mg.kg(-1) FFC), moderate-dose drug combination (200 mg.kg(-1) CGA + 15 mg.kg(-1) FFC), and a high-dose drug combination (400 mg.kg(-1) CGA + 30 mg.kg(-1) FFC) diets for 5 days. Compared with either drug alone, the shrimps in the FFC and CGA combination groups showed significantly lower cumulative mortality over 5 days after infection (p < 0.05). Moreover, in the drug combination groups, the vibrio density were consistently lower and the immune parameters were consistently higher than those in single drug groups (p < 0.05). In the drug combination groups, the hepatopancreatic tubule structure and integrity were better than those in the single drug groups. Thus, the use of FFC and CGA combined improved the survival rate, disease resistance, and immunity of shrimp challenged with VPAHPND compared with either drug alone. The use of FFC could be reduced to gain an improved therapeutic effect.