Prevention of Saprolegniasis in rainbow trout (Oncorhynchus mykiss) eggs using oregano (Origanum onites) and laurel (Laurus nobilis) essential oils.

The present study investigated the antifungal effects of essential oils of oregano (Origanum onites) and laurel (Laurus nobilis) on Saprolegniasis, a disease that occurs in rainbow trout eggs during the incubation period. Oregano and laurel were ground after drying, and essential oils were obtained by water distillation method using a Clevenger apparatus. The essential oils were added to potato dextrose agar (PDA) at the rates of 1-1000 ppm, and the minimum inhibitory concentration (MIC) was determined as 250 ppm whereas the minimum lethal concentration (MLC) was determined to be 500 ppm for both plants. In the in vivo trials, fertilized eggs were treated with predetermined doses either by bathing during water hardening and incubation period or only during incubation period, and death rates were monitored during embryological development. The best larvae hatching rate was determined in 500 ppm oregano and 500 ppm laurel groups treated during water hardening plus daily as 82.11% and 79.87%, respectively. According to the results, it was determined that oregano and laurel essential oils exhibited better results in all doses compared with the negative control group, and 500 ppm dose had a better effect than the positive control group treated with formalin.

Pharmacokinetics and Pharmacokinetic/Pharmacodynamic Integration of Enrofloxacin Following Single Oral Administration of Different Doses in Brown Trout (Salmo trutta).

The pharmacokinetic of enrofloxacin was investigated in brown trout (Salmo trutta) following oral administration of 10, 20, and 40 mg/kg doses at 11 ± 1.5 °C. Furthermore, MICs of enrofloxacin against Aeromonas hydrophila and A. sobria were determined. The plasma concentrations of enrofloxacin and ciprofloxacin were determined using HPLC-UV and analyzed by non-compartmental method. Following oral administration at dose of 10 mg/kg, total clearance (CL/F), area under the concentration-time curve (AUC0-∞) and peak plasma concentrations (Cmax) were 41.32 mL/h/kg, 242.02 h*µg/mL and 4.63 µg/mL, respectively. When compared to 10 mg/kg dose, the dose-normalized AUC0-∞ and Cmax were increased by 56.30% and 30.08%, respectively, while CL/F decreased by 38.4% at 40 mg/kg dose, suggesting the non-linearity. Ciprofloxacin was not detected in the all of plasma samples. The MIC values of enrofloxacin were ranged 0.0625-4 µg/mL for A. hydrophila and 0.0625-2 µg/mL for A. sobria. The oral administration of enrofloxacin at 10 (for 192 h) and 20 (for 240 h) mg/kg doses provided the AUC of enrofloxacin equal to 1.23 and 1.96-fold MICs, respectively, for A. hydrophila and A. sobria with the MIC90 values of 1 µg/mL. However, further researches are needed on the PK/PD study of enrofloxacin for the successful treatment of infections caused by A. hydrophila and A. sobria in brown trout.