Tetracycline in catfish (clarias batrachus) : emphasis on pharmacokinetics, prophylaxis and the minimal inhibitory concentration of tetracycline to aeromonas hydrophila

Abstract

The pharmacokinetics of tetracycline in catfish (Clarias batrachus) was studied after intraperitoneal administration (5 mg/kg catfish body weight), intramuscular administration (5 mg/kg catfish body weight) and oral administration (50 mg/kg catfish body weight). Microbiological assay was used for determining tetracycline levels in serum, muscle and liver. Lyophilization was applied in concentrating tetracycline, extracted from the tissues (muscle and liver) by 0.1 M phosphate buffer, pH 4.5. The average biological half-lives of tetracycline were 33.10 ± 4.80 h (in serum) and 33.61 ± 9.54 h (in muscle). The tetracycline absorption after the intraperitoneal administration was better than after the intramuscular and oral administration, respectively. Agar dilution techniques were used for the determination of the Minimal Inhibitory Concentration (MIC) of tetracycline to 57 strains of A.hydrophila. The MICs are varied from 0.51-130.35 mcg/ml. The result from the MIC study shows that A.hydrophila strains isolated from catfish (50.0%), snake-head fish (46.42%) and the environmental sources (37.5%) (water and soil in fish culturing ponds) resist to tetracycline, on the other hand, all strains isolated from humans and received from Japan Collection of Microorganisms are sensitive. Tetracycline, 5 mg/kg catfish body weight, administered intraperitoneally, was successfuly proved to preyent the A. hydrophila Fl81 infection in the catfish l00% within 3 days. The protection was decreased to 80%, 0% and 0% at d4, d6 and d7, respectively. Such result corresponds well with the theoretical tetracycline levels in muscle of the catfish after the intraperitoneal administration (5 mg/kg catfish body weight).