Virulence of Photobacterium damselae subsp. piscicida in cultured cobia Rachycentron canadum

Abstract

An outbreak of serious mortality among the cultured cobia Rachycentron canadum (weighing 3 kg) characterized by the presence of whitish granulomatous deposits on the kidney, liver and spleen occurred in July of 2000 in Taiwan. A non-motile strain CP1 was isolated from kidney and/or liver on tryptic soy agar and/or brain heart infusion agar plates (both supplemented with 1% NaCl, w/v). This strain was characterized and identified as Photobacterium damselae subsp. piscicida using biochemical characteristics and Bionor mono-Pp tests. The bacterium and its extracellular products (ECP) were lethal to the cobia (weighing 10 g) with LD50 values of 1.03 x 10(4) colony forming units and 1.26 microg protein/g fish body weight, respectively. All the moribund/dead fish exhibited darkness in color with no gross or internal leasions. However, the bacteria could be reisolated from kidney and liver after bacterial challenge. The present results reveal that Ph. damselae subsp. piscicida is the causative agent of fish photobacteriosis in the cobia and the bacterium isolated from sub-adult cobia (chronic form) is virulent to young cobia causing acute form of the disease.

First report of isolation and characterization of Photobacterium damselae subsp. damselae from cage‐farmed cobia (Rachycentron canadum)

“…Globally, mortality due to pasteurellosis in cage‐cultured cobia caused by Photobacterium damselae subsp. piscicida has been reported (Liu, Lin & Lee ). Vibriosis caused by Vibrio alginolyticus , V. harveyi , V. parahemolyticus and V. vulnificus has also been responsible for mortalities in cage‐cultured cobia (Rajan et al .…”

Cloning and characterization of Photobacterium damselae ssp. piscicida phospholipase: an enzyme that shows haemolytic activity

“…Since 1969 this disease has economically damaged the yellowtail, Seriola quinqueradiata (Temminck & Schlegel), aquaculture industry in Japan (Kitao 1993). Furthermore, pasteurellosis has also damaged cultured gilthead seabream and seabass in Europe (Toranzo, Barreiro, Casal, Figueras, Magariños & Barja 1991; Magariños, Toranzo & Romalde 1996), striped bass in the USA (Hawke, Plakas, Minton, McPhearson, Snider & Guarino 1987), and snakehead (Tung, Tsai, Ho, Huang & Chen 1985), cobia (Liu, Lin & Lee 2003) and hybrid striped bass (Huang, Tu, Chuang, Hung, Su & Lin 2001) in Taiwan.…”

Evaluating the protective efficacy of antigen combinations against Photobacterium damselae ssp. piscicida infections in cobia, Rachycentron canadum L.

“…piscicida (PFPP‐02) was cultured in brain–heart infusion broth (BHIB) (Himedia) containing with 3% NaCl, with agitation (200 rpm) for 24 h at 25 °C, and stored at −80 °C. Before each use, a fresh culture was started from a frozen sample (Liu, Lin & Lee ; Lin et al . ; Ho et al .…”

“…piscicida cell suspension in PBS (5 × 10 7 CFU per fish) was injected intraperitoneally to reach the 60% lethal dose (LD 60 ) (Liu et al . ; Lin et al . ; Ho et al .…”