361
Initially, it was considered that the organisms bore similarities to Aer. veronii
(Hickman-Brenner et al. 1987 ) and Ser. liquefaciens (Grimont and Grimont 2005b ).
Similarities with the former included the presence of Gram-negative fermentative,
catalase (and oxidase) positive rods, which were motile by single polar fl agella, and
with a G + C ratio of the DNA of 55 moles %. Indeed, the only discrepancies with
the defi nition of Aer. veronii concerned some sugar fermentation reactions. Yet,
similarities were also apparent with Ser. liquefaciens. However, the use of the API
20E rapid identifi cation system (profi le = 5305363 or 5305367) and whole cell
agglutination using a polyclonal antiserum raised against the type strain, confi rmed
an identifi cation as Ser. liquefaciens.
Epizootiology
The natural reservoir of the organism was probably polluted waters (McIntosh and
Austin 1990b ).
Pathogenicity
Injection of 10
3 cells killed Atlantic salmon within 72 h. Typically, there was pronounced muscle liquefaction within the vicinity of i.m. injections. ECP resulted in
death within 48 h (McIntosh and Austin 1990b ).
Disease Control
Vaccine Development Whole cell formalised vaccines and toxoid preparations
were effective for prophylaxis in laboratory-based experiments with Atlantic salmon
(McIntosh and Austin 1990b ).
Antimicrobial Compounds There was contradictory evidence regarding the value
of chemotherapy with oxytetracycline. Nevertheless, the disease could be controlled with oxolinic acid (McIntosh and Austin 1990b ).
Serratia marcescens
Characteristics of the Disease
The initial association of Ser. marcescens with fi sh diseases stemmed from a publication by Clausen and Duran-Reynals ( 1937 ). More detailed work waited for over
half a century when in July 1990 during a survey of white perch ( Morone
Serratia marcescens
Initially, it was considered that the organisms bore similarities to Aer. veronii
(Hickman-Brenner et al. 1987 ) and Ser. liquefaciens (Grimont and Grimont 2005b ).
Similarities with the former included the presence of Gram-negative fermentative,
catalase (and oxidase) positive rods, which were motile by single polar fl agella, and
with a G + C ratio of the DNA of 55 moles %. Indeed, the only discrepancies with
the defi nition of Aer. veronii concerned some sugar fermentation reactions. Yet,
similarities were also apparent with Ser. liquefaciens. However, the use of the API
20E rapid identifi cation system (profi le = 5305363 or 5305367) and whole cell
agglutination using a polyclonal antiserum raised against the type strain, confi rmed
an identifi cation as Ser. liquefaciens.
Epizootiology
The natural reservoir of the organism was probably polluted waters (McIntosh and
Austin 1990b ).
Pathogenicity
Injection of 10
3 cells killed Atlantic salmon within 72 h. Typically, there was pronounced muscle liquefaction within the vicinity of i.m. injections. ECP resulted in
death within 48 h (McIntosh and Austin 1990b ).
Disease Control
Vaccine Development Whole cell formalised vaccines and toxoid preparations
were effective for prophylaxis in laboratory-based experiments with Atlantic salmon
(McIntosh and Austin 1990b ).
Antimicrobial Compounds There was contradictory evidence regarding the value
of chemotherapy with oxytetracycline. Nevertheless, the disease could be controlled with oxolinic acid (McIntosh and Austin 1990b ).
Serratia marcescens
Characteristics of the Disease
The initial association of Ser. marcescens with fi sh diseases stemmed from a publication by Clausen and Duran-Reynals ( 1937 ). More detailed work waited for over
half a century when in July 1990 during a survey of white perch ( Morone
Serratia marcescens