Optimization of an Isolation Method for Ichthyobacterium seriolicida, the Causative Agent of Bacterial Hemolytic Jaundice

Abstract

We optimized a method for isolating Ichthyobacterium seriolicida, which is difficult to isolate even from freshly dead diseased fish. The bacterium was isolated from the blood of diseased yellowtail Seriola quinqueradiata up to 3 h after death, but not from the spleen, even when sampled immediately after death. The bacterium remained culturable from blood samples collected in medium-filled syringes and stored at 8°C for at least 72 h. Therefore, collecting blood within 3 h after death using a medium-filled syringe and storing it at low temperature is considered effective for preserving the viability of I. seriolicida.