31
fermentation profi le. Subsequently, Collins et al. ( 1987 ) demonstrated closer relationships with other carnobacteria.
Epizootiology
It would appear that the disease is confi ned to Europe and North America. However,
it is unclear whether fi sh are the natural hosts for Car. piscicola and other lactobacilli, or if they comprise part of the natural aquatic microfl ora.
Pathogenicity
Small-scale experiments with rainbow trout maintained in fresh water at 18 °C have
shown that death may result within 14 days of i.p. injection of 10
5 cells/fi sh. Dead
and moribund fi sh had swollen kidneys, and ascitic fl uid accumulated in the abdominal cavity. However, adverse effects were not recorded following injection of cellfree extracts. This suggests that exotoxins did not exert a signifi cant role in
pathogenicity. It remains for further work to elucidate the effect, if any, of endotoxins (Ross and Toth 1974 ; Cone 1982 ; Hiu et al. 1984 .
Disease Control
Antimicrobial Compounds In vitro methods have shown that isolates are sensitive to ampicillin, cephaloridine, chloramphenicol, furazolidone and tetracycline,
but not to erythromycin, novobiocin, streptomycin, sulphamerazine or sulphamethoxazole (Michel et al. 1986 ; B. Austin, unpublished data). Unfortunately, these
antimicrobial compounds have not been evaluated in fi sh.
Leuconostocacceae Representative
Weissella sp.
Characteristics of the Disease
Liu et al. ( 2009 ) reported Weissella as the causative agent of a disease in rainbow trout
culture in China. Subsequently, a similar organism has been associated with haemorrhagic septicaemia of rainbow trout farmed in Brazil during 2008 and 2009 when
there was increased water temperature (≥17 °C). Disease signs included anorexia,
lethargy, ascites, exophthalmia and hemorrhages in/on the eyes, mouth, oral cavity
and tongue (Figueiredo et al. 2012 ). Weissellosis was recognised during 2011 in rainbow trout in the USA with disease signs including darkening of the skin, lethargy,
bilateral exophthalmia, corneal opacity, ocular haemorrhaging and occasional corneal
rupture, and possibly cerebral haemorrhaging (Welch and Good 2013 ).
Leuconostocacceae Representative
fermentation profi le. Subsequently, Collins et al. ( 1987 ) demonstrated closer relationships with other carnobacteria.
Epizootiology
It would appear that the disease is confi ned to Europe and North America. However,
it is unclear whether fi sh are the natural hosts for Car. piscicola and other lactobacilli, or if they comprise part of the natural aquatic microfl ora.
Pathogenicity
Small-scale experiments with rainbow trout maintained in fresh water at 18 °C have
shown that death may result within 14 days of i.p. injection of 10
5 cells/fi sh. Dead
and moribund fi sh had swollen kidneys, and ascitic fl uid accumulated in the abdominal cavity. However, adverse effects were not recorded following injection of cellfree extracts. This suggests that exotoxins did not exert a signifi cant role in
pathogenicity. It remains for further work to elucidate the effect, if any, of endotoxins (Ross and Toth 1974 ; Cone 1982 ; Hiu et al. 1984 .
Disease Control
Antimicrobial Compounds In vitro methods have shown that isolates are sensitive to ampicillin, cephaloridine, chloramphenicol, furazolidone and tetracycline,
but not to erythromycin, novobiocin, streptomycin, sulphamerazine or sulphamethoxazole (Michel et al. 1986 ; B. Austin, unpublished data). Unfortunately, these
antimicrobial compounds have not been evaluated in fi sh.
Leuconostocacceae Representative
Weissella sp.
Characteristics of the Disease
Liu et al. ( 2009 ) reported Weissella as the causative agent of a disease in rainbow trout
culture in China. Subsequently, a similar organism has been associated with haemorrhagic septicaemia of rainbow trout farmed in Brazil during 2008 and 2009 when
there was increased water temperature (≥17 °C). Disease signs included anorexia,
lethargy, ascites, exophthalmia and hemorrhages in/on the eyes, mouth, oral cavity
and tongue (Figueiredo et al. 2012 ). Weissellosis was recognised during 2011 in rainbow trout in the USA with disease signs including darkening of the skin, lethargy,
bilateral exophthalmia, corneal opacity, ocular haemorrhaging and occasional corneal
rupture, and possibly cerebral haemorrhaging (Welch and Good 2013 ).
Leuconostocacceae Representative