352
Pathogenicity
Cultures could induce fi n and tail rot by immersion for 5 min in 10
7 bacteria/ml, but
only after prior abrading the surface of the fi ns. Disease signs became evident after
3 days, with mortalities being recorded after a further 2 days. Within 5 days of
injecting 10
4 cells/fi sh, there was some reddening of the muscle in animals injected
intramuscularly. Seven days after i.m. and i.p. injection, mortalities began, with
disease signs including gastro-enteritis, liquefaction of the kidney, and the presence
of ascitic fl uid in the peritoneal cavity. All fi sh were dead within 12 days (Daskalov
et al. 1998 ).
Pantoea agglomerans
Characteristics of the Disease
Juvenile mahi mahi (average weight = 1 g) were transported from Florida, USA to
Bermuda for ongrowing in sea cages. During January 1986, mortalities were noted
with dead specimens displaying marked haemorrhaging in the eyes. Pronounced
haemorrhaging was noted in the eyes of dead and moribund animals. Haemorrhages
were also recorded in the musculature. Otherwise, there was an absence of disease
signs in the internal organs (Hansen et al. 1990 ).
Isolation
Pale yellow colonies were recovered from kidney blood on TSA supplemented with
2 % (w/v) NaCl following incubation at 16 °C for 7 days. Subculturing was possible
on marine 2216E agar (Hansen et al. 1990 ).
Box 6.8: Klebsiella pneumoniae
Cultures comprise fermentative Gram-negative encapsulated rods that produce catalase but not arginine dihydrolase, H 2 S, indole, lysine or ornithine
decarboxylase, oxidase nor phenylalanine deaminase, produce acid from
arabinose, cellobiose, glucose, maltose and raffi nose, reduce nitrates to nitrite,
and do not degrade gelatin (Daskalov et al. 1998 ).
6 Enterobacteriaceae Representatives
Pathogenicity
Cultures could induce fi n and tail rot by immersion for 5 min in 10
7 bacteria/ml, but
only after prior abrading the surface of the fi ns. Disease signs became evident after
3 days, with mortalities being recorded after a further 2 days. Within 5 days of
injecting 10
4 cells/fi sh, there was some reddening of the muscle in animals injected
intramuscularly. Seven days after i.m. and i.p. injection, mortalities began, with
disease signs including gastro-enteritis, liquefaction of the kidney, and the presence
of ascitic fl uid in the peritoneal cavity. All fi sh were dead within 12 days (Daskalov
et al. 1998 ).
Pantoea agglomerans
Characteristics of the Disease
Juvenile mahi mahi (average weight = 1 g) were transported from Florida, USA to
Bermuda for ongrowing in sea cages. During January 1986, mortalities were noted
with dead specimens displaying marked haemorrhaging in the eyes. Pronounced
haemorrhaging was noted in the eyes of dead and moribund animals. Haemorrhages
were also recorded in the musculature. Otherwise, there was an absence of disease
signs in the internal organs (Hansen et al. 1990 ).
Isolation
Pale yellow colonies were recovered from kidney blood on TSA supplemented with
2 % (w/v) NaCl following incubation at 16 °C for 7 days. Subculturing was possible
on marine 2216E agar (Hansen et al. 1990 ).
Box 6.8: Klebsiella pneumoniae
Cultures comprise fermentative Gram-negative encapsulated rods that produce catalase but not arginine dihydrolase, H 2 S, indole, lysine or ornithine
decarboxylase, oxidase nor phenylalanine deaminase, produce acid from
arabinose, cellobiose, glucose, maltose and raffi nose, reduce nitrates to nitrite,
and do not degrade gelatin (Daskalov et al. 1998 ).
6 Enterobacteriaceae Representatives