Efficacy of a commercial disinfectant against Vibrio ordalii, Vibrio anguillarum, Francisella sp. and Infectious Pancreatic Necrosis Virus (IPNV) pathogens of Atlantic salmon (Salmo salar) farmed in Chile

Abstract

The efficacy of the disinfectant Duplalim^®, a synergistic blend of superquats and glutaraldehyde, was analysed in vitro against 4 fish pathogens. All concentrations tested (1:200 to 1:400 dilutions) were efficacious on killing Vibrio ordalii and Vibrio anguillarum in seawater after 30 s, being the level of reduction equal to 1.8 x 10⁶ CFU/ml. Higher concentration of Duplalim^® (1:50 dilutions) and time of exposure (at least 5 min) is needed to kill completely Francisella sp, an intracellular freshwater pathogen. When Infectious Pancreatic Necrosis Virus (IPNV) was treated with 1:400 disinfectant dilution, this concentration had a significant effect after 2 minutes, regardless of the IPNV titres employed (concentration greater than 10^7.6 TCID₅₀/ml). Duplalim^® was tested in large scale against Vibrionaceae members. In comparison to the controls (without the disinfectant), 1:400 dilutions of Duplalim^®totally killed V. ordalii and V. anguillarum in seawater as well as on the surface of the fishing net (used in the cages of cultured salmon) after 15 min. Cultivable bacteria remained constant in the buckets without the disinfectant (1.4 ± 0.3 × 10⁶ CFU/ml), regardless of the period sampled. In the case of the adherence on the fishing net, bacteria not exposed to the disinfectant were detected at a concentration of 7.6 ± 3.2 × 10⁵ CFU/ml. These data indicate that the use of Duplalim^® against V. ordalii, V. anguillarum and IPNV is effective in low concentration and short time of exposure (15 min at a concentration of 1:400 dilutions), while the intracellular pathogen requires higher concentration.