351
Pathogenicity
The culture caused clinical disease in laboratory experiments with rainbow trout.
Injection (subcutaneous) of rainbow trout, weighing 150–200 g, and maintained at
a water temperature of 4–6 °C, resulted in clinical disease, with mortalities occurring between 3 and 10 days.
In the subsequent study by Teshima et al. ( 1992 ), it was reported that disease
took 3 months to develop at 15 °C following i.p. injection with 5 × 10
6 to 3 × 10
7
cells/ml. So, the inference was that the organism was not very aggressive. Yet,
brown trout appeared to be more susceptible with LD 50 doses of 21.5 × 10
4 (an isolate from human enteritis, UK) to 7.4 × 10
7 cells (an isolate from rainbow trout in
Spain) depending on the culture (Acosta et al. 2002 ).
Using 23 isolates that were at best of extremely low virulence to gilthead sea
bream, pathogenicity was correlated with the bacteriocidal effect of serum. However
in the absence of any clinical signs of disease, the pathogen was capable of remaining viable within the gilthead sea bream for up to 3 months (Padilla et al. 2005 ).
Klebsiella pneumoniae
Characteristics of the Disease
The organism was recovered from the diseased tails and fi ns of 12 rainbow trout in
Scotland. No other disease signs were noted (Daskalov et al. 1998 ).
Isolation
Pure cultures were obtained after shaking tails and pectoral fi ns in 0.9 % (w/v) saline
for 5 min, and thereafter spreading 0.1 ml volumes on TSA with incubation at 15 °C
for 7 days (Daskalov et al. 1998 ).
Characteristics of the Pathogen
Twelve pure cultures were obtained. The characteristics were, as follows:
Klebsiella pneumoniae
Pathogenicity
The culture caused clinical disease in laboratory experiments with rainbow trout.
Injection (subcutaneous) of rainbow trout, weighing 150–200 g, and maintained at
a water temperature of 4–6 °C, resulted in clinical disease, with mortalities occurring between 3 and 10 days.
In the subsequent study by Teshima et al. ( 1992 ), it was reported that disease
took 3 months to develop at 15 °C following i.p. injection with 5 × 10
6 to 3 × 10
7
cells/ml. So, the inference was that the organism was not very aggressive. Yet,
brown trout appeared to be more susceptible with LD 50 doses of 21.5 × 10
4 (an isolate from human enteritis, UK) to 7.4 × 10
7 cells (an isolate from rainbow trout in
Spain) depending on the culture (Acosta et al. 2002 ).
Using 23 isolates that were at best of extremely low virulence to gilthead sea
bream, pathogenicity was correlated with the bacteriocidal effect of serum. However
in the absence of any clinical signs of disease, the pathogen was capable of remaining viable within the gilthead sea bream for up to 3 months (Padilla et al. 2005 ).
Klebsiella pneumoniae
Characteristics of the Disease
The organism was recovered from the diseased tails and fi ns of 12 rainbow trout in
Scotland. No other disease signs were noted (Daskalov et al. 1998 ).
Isolation
Pure cultures were obtained after shaking tails and pectoral fi ns in 0.9 % (w/v) saline
for 5 min, and thereafter spreading 0.1 ml volumes on TSA with incubation at 15 °C
for 7 days (Daskalov et al. 1998 ).
Characteristics of the Pathogen
Twelve pure cultures were obtained. The characteristics were, as follows:
Klebsiella pneumoniae