49
(Epinephelus lanceolatus), was described, and which effectively extended the geographical range of the pathogen to Australia (Bowater et al. 2012 ).
Characteristics of the Pathogen
Str. diffi cilis was described to accommodate what was perceived to be a new species
of fi sh pathogen causing meningo-encephalitis in cultured fi sh, which was fi rst recognised in Israel during 1984 (Eldar et al. 1994 , 1995b ). The initial work with diseased fi sh resulted in the recognition of two groups of streptococci; the separation
being achieved by use of API 50 CH and API 20 STREP, and by growth and haemolysis characteristics (Eldar et al. 1994 ). A fairly unreactive non-haemolytic mannitol negative group was labelled as Str. diffi cile (Eldar et al. 1994 ) , and the specifi c
epithet corrected to diffi cilis, i.e. Str. diffi cilis (Euzéby 1998 ), whereas a second
more reactive α-haemolytic, mannitol positive group became known as Str. shiloi.
On the basis of a comparative study including use of DNA:DNA hybridisation, Str.
diffi cilis recognised to be a synonym of Str. agalactiae, which has precedence in
nomenclature (Kawamura et al. 2005 ).
These isolates were considered to belong to a separate and distinct DNA homology group, with DNA relatedness between members of 89–100 % (Eldar et al.
1994 ). The level of DNA relatedness with Str. shiloi (= Str. iniae) was 17 % (Eldar
et al. 1994 ). Then, whole-cell protein electrophoresis revealed that the type strain of
Str. diffi cilis was indistinguishable to Str. agalactiae (Vandamme et al. 1997 ), which
had also been named as a fi sh pathogen (e.g. Evans et al. 2002 ). Moreover, it was
determined that Str. diffi cilis, which was originally regarded as serologically untypeable (Eldar et al. 1994 ), cross reacted with group B Streptococcus, namely capsular
Box 2.12: Streptococcus agalactiae
Colonies on BHIA are 1 mm in diameter, and non-pigmented after incubation
aerobically for 24 h at 30 °C. Cultures comprise encapsulated fermentative,
catalase-negative Gram-positive cocci of varying diameters in small chains,
which do not grow at 10, 37 or 45 °C, or in 40 % bile or 6.5 % (w/v) sodium
chloride, but do grow at pH 9.6. The isolates attack (produced acid from)
N-acetyl-glucosamine, D-fructose, D-glucose, maltose, D-mannose, ribose
and saccharose, but not adonitol, aesculin, amygdalin, L- or D-arabinose, Lor D-arabitol, arbutin, cellobiose, dulcitol, erythritol, L- or D-fucose, galactose, gentiobiose, M-D-glucoside, glycerol, glycogen, inositol, inulin, lactose,
melibiose, D-raffi nose, rhamnose, salicin, sorbitol, L-sorbose, starch, turanose, xylitol, L- or D-xylose or M-xyloside. Alkaline phosphatase, arginine
dihydrolase and leucine arylamidase are produced, but not α- nor ß -galactosidase, pyrrolidonylarylamidase nor ß-glucuronidase. The Voges Proskauer
reaction is positive. Bovine blood is not attacked (Eldar et al. 1994 ).
Streptococcaceae Representatives
(Epinephelus lanceolatus), was described, and which effectively extended the geographical range of the pathogen to Australia (Bowater et al. 2012 ).
Characteristics of the Pathogen
Str. diffi cilis was described to accommodate what was perceived to be a new species
of fi sh pathogen causing meningo-encephalitis in cultured fi sh, which was fi rst recognised in Israel during 1984 (Eldar et al. 1994 , 1995b ). The initial work with diseased fi sh resulted in the recognition of two groups of streptococci; the separation
being achieved by use of API 50 CH and API 20 STREP, and by growth and haemolysis characteristics (Eldar et al. 1994 ). A fairly unreactive non-haemolytic mannitol negative group was labelled as Str. diffi cile (Eldar et al. 1994 ) , and the specifi c
epithet corrected to diffi cilis, i.e. Str. diffi cilis (Euzéby 1998 ), whereas a second
more reactive α-haemolytic, mannitol positive group became known as Str. shiloi.
On the basis of a comparative study including use of DNA:DNA hybridisation, Str.
diffi cilis recognised to be a synonym of Str. agalactiae, which has precedence in
nomenclature (Kawamura et al. 2005 ).
These isolates were considered to belong to a separate and distinct DNA homology group, with DNA relatedness between members of 89–100 % (Eldar et al.
1994 ). The level of DNA relatedness with Str. shiloi (= Str. iniae) was 17 % (Eldar
et al. 1994 ). Then, whole-cell protein electrophoresis revealed that the type strain of
Str. diffi cilis was indistinguishable to Str. agalactiae (Vandamme et al. 1997 ), which
had also been named as a fi sh pathogen (e.g. Evans et al. 2002 ). Moreover, it was
determined that Str. diffi cilis, which was originally regarded as serologically untypeable (Eldar et al. 1994 ), cross reacted with group B Streptococcus, namely capsular
Box 2.12: Streptococcus agalactiae
Colonies on BHIA are 1 mm in diameter, and non-pigmented after incubation
aerobically for 24 h at 30 °C. Cultures comprise encapsulated fermentative,
catalase-negative Gram-positive cocci of varying diameters in small chains,
which do not grow at 10, 37 or 45 °C, or in 40 % bile or 6.5 % (w/v) sodium
chloride, but do grow at pH 9.6. The isolates attack (produced acid from)
N-acetyl-glucosamine, D-fructose, D-glucose, maltose, D-mannose, ribose
and saccharose, but not adonitol, aesculin, amygdalin, L- or D-arabinose, Lor D-arabitol, arbutin, cellobiose, dulcitol, erythritol, L- or D-fucose, galactose, gentiobiose, M-D-glucoside, glycerol, glycogen, inositol, inulin, lactose,
melibiose, D-raffi nose, rhamnose, salicin, sorbitol, L-sorbose, starch, turanose, xylitol, L- or D-xylose or M-xyloside. Alkaline phosphatase, arginine
dihydrolase and leucine arylamidase are produced, but not α- nor ß -galactosidase, pyrrolidonylarylamidase nor ß-glucuronidase. The Voges Proskauer
reaction is positive. Bovine blood is not attacked (Eldar et al. 1994 ).
Streptococcaceae Representatives