194
Pathogenicity
Esteve ( 1995 ) and Esteve et al. ( 1995b ) reported a high LD 50 dose of ~10
6 cells for
eel. Possibly, the ECP activity, which was equated with production of caseinase,
collagenase, elastase, protease, lipase and haemolysin, caused pathogenicity (Esteve
et al. 1995b ).
Aeromonas piscicola
Characteristics of the Pathogen
Aeromonas schubertii
Characteristics of the Disease
An epizootic, with cumulative losses of 45 % over 40 days, occurred in 18-month
old snakeheads ( Ophiocephalus argus) , which were farmed in earthern ponds (water
temperature = 26–28 °C) in Xianning, China during summer, 2009. The disease
signs included inappetance, lethargy, listless swimming, and the presence of whitish
nodules of 0.5–1.0 mm in diameter in the kidney, and blood clots in the liver (Liu
and Li 2012 ). The possibility of Mycobacterium or Nocardia being associated with
the nodules was ruled out by sequencing of the 16S rRNA gene. Necrosis and congestion in liver, kidney and spleen and damage to the heart muscle, intestine and
gills has been documented (Chen et al. 2012 ).
Isolation
Isolation from blood, kidney, liver and spleen of moribund fi sh was achieved on
BHIA plates with incubation at 28 °C for 48 h (Liu and Li 2012 ).
Box 4.6: Aer. piscicola
Cultures are motile but do not form a brown diffusible pigment, produce
ß-haemolysis, indole and lysine decarboxylase but not ornithine decarboxylase, are negative for the Voges Proskauer reaction, degrade aesculin and elastin, and produce acid from glycerol, salicin, and sucrose but not from
L-arabinose, D-cellobiose or lactose (Beaz-Hidalgo et al. 2009 ).
4 Aeromonadaceae Representatives (Motile Aeromonads)
Pathogenicity
Esteve ( 1995 ) and Esteve et al. ( 1995b ) reported a high LD 50 dose of ~10
6 cells for
eel. Possibly, the ECP activity, which was equated with production of caseinase,
collagenase, elastase, protease, lipase and haemolysin, caused pathogenicity (Esteve
et al. 1995b ).
Aeromonas piscicola
Characteristics of the Pathogen
Aeromonas schubertii
Characteristics of the Disease
An epizootic, with cumulative losses of 45 % over 40 days, occurred in 18-month
old snakeheads ( Ophiocephalus argus) , which were farmed in earthern ponds (water
temperature = 26–28 °C) in Xianning, China during summer, 2009. The disease
signs included inappetance, lethargy, listless swimming, and the presence of whitish
nodules of 0.5–1.0 mm in diameter in the kidney, and blood clots in the liver (Liu
and Li 2012 ). The possibility of Mycobacterium or Nocardia being associated with
the nodules was ruled out by sequencing of the 16S rRNA gene. Necrosis and congestion in liver, kidney and spleen and damage to the heart muscle, intestine and
gills has been documented (Chen et al. 2012 ).
Isolation
Isolation from blood, kidney, liver and spleen of moribund fi sh was achieved on
BHIA plates with incubation at 28 °C for 48 h (Liu and Li 2012 ).
Box 4.6: Aer. piscicola
Cultures are motile but do not form a brown diffusible pigment, produce
ß-haemolysis, indole and lysine decarboxylase but not ornithine decarboxylase, are negative for the Voges Proskauer reaction, degrade aesculin and elastin, and produce acid from glycerol, salicin, and sucrose but not from
L-arabinose, D-cellobiose or lactose (Beaz-Hidalgo et al. 2009 ).
4 Aeromonadaceae Representatives (Motile Aeromonads)