359
with commercial Salmonella antisera, although not specifi cally a product to Sal.
enterica subsp. arizonae (Kodama et al. 1987 ).
Epizootiology
Presumably, the pathogen had been derived from the aquarium water or from fi sh
(carriers) (Kodama et al. 1987 ).
Pathogenicity
The pathogenicity of the single isolate was not confi rmed (Kodama et al. 1987 ).
Disease Control
Antimicrobial Compounds Although control regimes were not adopted, the isolate was sensitive to chloramphenicol, fradiomycin, gentamicin, kanamycin, nalidixic acid, oxytetracycline, streptomycin and tetracycline, but resistant to
erythromycin, spiramycin and sulphadimethoxine (Kodama et al. 1987 ).
Serratia liquefaciens
Characteristics of the Disease
During spring and early summer of 1988, heavy mortalities, i.e. up to 30 % of the
stock, were noted among three separate populations of Atlantic salmon ( Salmo
salar L.), two of which (average weight = 450 g) were in Scottish marine cage sites,
and the third population (average weight = 25 g) was in freshwater. Since the initial
occurrence, the disease has been recognised on another two marine sites in Scotland
during 1990. Also in 1990, the organism was recognised as the cause of low continuous mortalities among farmed turbot in France (Vigneulle and Baudin-Laurençin
1995 ). Moribund fi sh did not display any external signs of disease. Yet, internally
the kidney was swollen, and nodules were present on both the kidney and spleen;
the liver appeared speckled, and some ascitic fl uid was present in the peritoneal cavity. Initially, it was considered likely that the animals were infected with Ren. salmoninarum , the causal agent of BKD, but the presence of Gram-negative bacteria
and complete absence of any Gram-positive micro-organisms precluded this possibility (McIntosh and Austin 1990a , b ). Microscopic examination of formalin- fi xed
Serratia liquefaciens
with commercial Salmonella antisera, although not specifi cally a product to Sal.
enterica subsp. arizonae (Kodama et al. 1987 ).
Epizootiology
Presumably, the pathogen had been derived from the aquarium water or from fi sh
(carriers) (Kodama et al. 1987 ).
Pathogenicity
The pathogenicity of the single isolate was not confi rmed (Kodama et al. 1987 ).
Disease Control
Antimicrobial Compounds Although control regimes were not adopted, the isolate was sensitive to chloramphenicol, fradiomycin, gentamicin, kanamycin, nalidixic acid, oxytetracycline, streptomycin and tetracycline, but resistant to
erythromycin, spiramycin and sulphadimethoxine (Kodama et al. 1987 ).
Serratia liquefaciens
Characteristics of the Disease
During spring and early summer of 1988, heavy mortalities, i.e. up to 30 % of the
stock, were noted among three separate populations of Atlantic salmon ( Salmo
salar L.), two of which (average weight = 450 g) were in Scottish marine cage sites,
and the third population (average weight = 25 g) was in freshwater. Since the initial
occurrence, the disease has been recognised on another two marine sites in Scotland
during 1990. Also in 1990, the organism was recognised as the cause of low continuous mortalities among farmed turbot in France (Vigneulle and Baudin-Laurençin
1995 ). Moribund fi sh did not display any external signs of disease. Yet, internally
the kidney was swollen, and nodules were present on both the kidney and spleen;
the liver appeared speckled, and some ascitic fl uid was present in the peritoneal cavity. Initially, it was considered likely that the animals were infected with Ren. salmoninarum , the causal agent of BKD, but the presence of Gram-negative bacteria
and complete absence of any Gram-positive micro-organisms precluded this possibility (McIntosh and Austin 1990a , b ). Microscopic examination of formalin- fi xed
Serratia liquefaciens