467
© Springer International Publishing Switzerland 2016
B. Austin, D.A. Austin, Bacterial Fish Pathogens,
DOI 10.1007/978-3-319-32674-0_8
Chapter 8
Francisellaceae Representatives
Abstract Francisella noatunensis and Fr. noatunensis subsp. orientalis are intracellular pathogens which cause granulomatous disease. Isolation has been achieved
initially in cell culture with subsequent growth on cysteine heart agar. Disease control has been achieved by vaccination and by use of antimicrobial compounds, notably fl orfenicol.
Keywords Francisella • Granulomas • Intracellular • Vaccines • Diagnosis
Isolation
Initially, francisellas were grown in cell cultures at 20 °C. Subculturing onto cysteine heart agar at 22 °C resulted in dense growth of small opaque colonies, which
increased to 2–3 mm in diameter (Olsen et al. 2006 ). However, Kamaishi et al.
( 2005 ) managed to recover an organism from the spleen of an infected three-line
grunt using cysteine heart agar supplemented with 1 % (w/v) haemoglobin. Also,
isolation has been achieved on Thayer Martin agar within 4-days of incubation
(Soto et al. 2014 ) and on modifi ed cysteine heart agar (Lewisch et al. 2014 ).
Francisella noatunensis
Characteristics of the Disease
The pathogen has been found in both wild and farmed Atlantic cod in Norway with
heavy losses in many farms (Ottem et al. 2008 ). Mature farmed cod, with an average
weight of 3 kg, and which were contained in sea cages in Norway, developed mortalities in July 2005 when the water temperature was 14.5 °C. Mortalities peaked in
August, and over the 5-month period to November ~40 % of the stock had died.
Initially, clinical signs of disease were not noted, but later the fi sh were observed to
be swimming sluggishly, were generally inappetant, and became emaciated. Some
fi sh displayed dermal haemorrhagic nodules, and corneal opacity and perforation.
© Springer International Publishing Switzerland 2016
B. Austin, D.A. Austin, Bacterial Fish Pathogens,
DOI 10.1007/978-3-319-32674-0_8
Chapter 8
Francisellaceae Representatives
Abstract Francisella noatunensis and Fr. noatunensis subsp. orientalis are intracellular pathogens which cause granulomatous disease. Isolation has been achieved
initially in cell culture with subsequent growth on cysteine heart agar. Disease control has been achieved by vaccination and by use of antimicrobial compounds, notably fl orfenicol.
Keywords Francisella • Granulomas • Intracellular • Vaccines • Diagnosis
Isolation
Initially, francisellas were grown in cell cultures at 20 °C. Subculturing onto cysteine heart agar at 22 °C resulted in dense growth of small opaque colonies, which
increased to 2–3 mm in diameter (Olsen et al. 2006 ). However, Kamaishi et al.
( 2005 ) managed to recover an organism from the spleen of an infected three-line
grunt using cysteine heart agar supplemented with 1 % (w/v) haemoglobin. Also,
isolation has been achieved on Thayer Martin agar within 4-days of incubation
(Soto et al. 2014 ) and on modifi ed cysteine heart agar (Lewisch et al. 2014 ).
Francisella noatunensis
Characteristics of the Disease
The pathogen has been found in both wild and farmed Atlantic cod in Norway with
heavy losses in many farms (Ottem et al. 2008 ). Mature farmed cod, with an average
weight of 3 kg, and which were contained in sea cages in Norway, developed mortalities in July 2005 when the water temperature was 14.5 °C. Mortalities peaked in
August, and over the 5-month period to November ~40 % of the stock had died.
Initially, clinical signs of disease were not noted, but later the fi sh were observed to
be swimming sluggishly, were generally inappetant, and became emaciated. Some
fi sh displayed dermal haemorrhagic nodules, and corneal opacity and perforation.