48
pathogenic lactococci/Group N streptococci have been studied, and named as a new
species, i.e. Lactococcus piscium (Williams et al. 1990 ).
Streptococcus agalactiae (= Str. diffi cilis)
Characteristics of the Disease
Str. diffi cilis was named as a result of an outbreak of disease in St. Peter’s fi sh (tilapia) and rainbow trout within Israel during 1986. The disease spread rapidly, and
caused severe economic losses in the farmed fi sh (Eldar et al. 1994 ). Diseased tilapia were lethargic, swam erratically, and showed signs of dorsal rigidity. In rainbow
trout, the disease signs were consistent with a septicaemia, with brain damage
(Eldar et al. 1994 ). An organism, identifi ed as Str. agalactiae , was recovered from
diseased cultured silver pomfret in Kuwait (Duremdez et al. 2004 ; Azad et al. 2012 ).
Duremdez et al. ( 2004 ) described disease signs including inappetance, lethargy,
swollen abdomen, the stomach and intestine fi lled with a gelatinous or yellowish
fl uid, and in some fi sh slight haemorrhaging in the eye, exophthalmia and corneal
opacity. Also, the liver was enlarged, there was evidence of congestion of the kidney
and spleen, and fl uid occurred in the peritoneal cavity (Duremdez et al. 2004 ). Azad
et al. ( 2012 ) reported anorexia and gradual darkening of larvae. Bacteria were
recovered from brain tissue. Exophthalmia, haemorrhagic septicaemia, meningoencephalitis and multiple necrotic foci in tissues was reported by others (Suanyuk
et al. 2008 ). An outbreak in wild fi sh including the giant Queensland grouper
Box 2.11: Lactococcus piscium
From the available information, it is apparent that cultures comprise Grampositive non-motile, facultatively anaerobic short (ovoid) rods, which are
catalase negative, grow at 5–30 °C, produce acid from amygdalin, L-arabinose,
arbutin,
N-acetylglucosamine,
cellobiose,
D-fructose,
galactose,
ß- gentiobiose, gluconate, glucose, lactose, maltose, D-mannose, mannitol,
melibiose, melezitose, D-raffi nose, ribose, salicin, sucrose, trehalose,
D-turanose and D-xylose, but not adonitol, D-arabinose, D or L-arabitol, dulcitol, erythritol, D and L-fucose, glycogen, glycerol, inositol, inulin, 2 and
5-ketogluconate, D-lyxose, α-methyl-D-glucoside, α -methyl-D-mannoside,
ß-methyl-xyloside, rhamnose, L-sorbose, sorbitol, D-tagatose, xylitol and
L-xylose. Aesculin and starch (slow, weak reaction) but not arginine is
degraded. H 2 S is not produced. The long chain cellular fatty acids are considered to be of the straight chain saturated, mono-unsaturated and cyclopropanering types. The major acids correspond to hexadecanoic acid, ∆ 11-octadecanoic
acid and ∆ 11-methylenoctadecanoic acid. The G + C ratio of the DNA is
calculated as 38.5 moles %.
2 Gram-Positive Bacteria (Anaerobes and ‘Lactic Acid’ Bacteria)
pathogenic lactococci/Group N streptococci have been studied, and named as a new
species, i.e. Lactococcus piscium (Williams et al. 1990 ).
Streptococcus agalactiae (= Str. diffi cilis)
Characteristics of the Disease
Str. diffi cilis was named as a result of an outbreak of disease in St. Peter’s fi sh (tilapia) and rainbow trout within Israel during 1986. The disease spread rapidly, and
caused severe economic losses in the farmed fi sh (Eldar et al. 1994 ). Diseased tilapia were lethargic, swam erratically, and showed signs of dorsal rigidity. In rainbow
trout, the disease signs were consistent with a septicaemia, with brain damage
(Eldar et al. 1994 ). An organism, identifi ed as Str. agalactiae , was recovered from
diseased cultured silver pomfret in Kuwait (Duremdez et al. 2004 ; Azad et al. 2012 ).
Duremdez et al. ( 2004 ) described disease signs including inappetance, lethargy,
swollen abdomen, the stomach and intestine fi lled with a gelatinous or yellowish
fl uid, and in some fi sh slight haemorrhaging in the eye, exophthalmia and corneal
opacity. Also, the liver was enlarged, there was evidence of congestion of the kidney
and spleen, and fl uid occurred in the peritoneal cavity (Duremdez et al. 2004 ). Azad
et al. ( 2012 ) reported anorexia and gradual darkening of larvae. Bacteria were
recovered from brain tissue. Exophthalmia, haemorrhagic septicaemia, meningoencephalitis and multiple necrotic foci in tissues was reported by others (Suanyuk
et al. 2008 ). An outbreak in wild fi sh including the giant Queensland grouper
Box 2.11: Lactococcus piscium
From the available information, it is apparent that cultures comprise Grampositive non-motile, facultatively anaerobic short (ovoid) rods, which are
catalase negative, grow at 5–30 °C, produce acid from amygdalin, L-arabinose,
arbutin,
N-acetylglucosamine,
cellobiose,
D-fructose,
galactose,
ß- gentiobiose, gluconate, glucose, lactose, maltose, D-mannose, mannitol,
melibiose, melezitose, D-raffi nose, ribose, salicin, sucrose, trehalose,
D-turanose and D-xylose, but not adonitol, D-arabinose, D or L-arabitol, dulcitol, erythritol, D and L-fucose, glycogen, glycerol, inositol, inulin, 2 and
5-ketogluconate, D-lyxose, α-methyl-D-glucoside, α -methyl-D-mannoside,
ß-methyl-xyloside, rhamnose, L-sorbose, sorbitol, D-tagatose, xylitol and
L-xylose. Aesculin and starch (slow, weak reaction) but not arginine is
degraded. H 2 S is not produced. The long chain cellular fatty acids are considered to be of the straight chain saturated, mono-unsaturated and cyclopropanering types. The major acids correspond to hexadecanoic acid, ∆ 11-octadecanoic
acid and ∆ 11-methylenoctadecanoic acid. The G + C ratio of the DNA is
calculated as 38.5 moles %.
2 Gram-Positive Bacteria (Anaerobes and ‘Lactic Acid’ Bacteria)