54
with septicaemia and subcutaneous abscesses in the tail region of Nile tilapia in
Brazil (Netto et al. 2011 ). The organism has also been recovered from diseased
Amur sturgeon ( Acipenser schrenckii ) in China (Yang and Li 2009 ).
Isolation
Str. dysgalactiae has been recovered as orange colonies on Todd-Hewitt agar supplemented with 30 μg/ml of Congo red with incubation at 37 °C for 30 h (Abdelsalam
et al. 2009 ). These could be readily distinguished from Lactococcus garvieae that
produced white or pale orange colonies on the media (Abdelsalam et al. 2009 ).
Characteristics of the Pathogen
Identifi cation was confi rmed by the results of 16S rDNA sequencing (Nomoto
et al. 2004 ; 2006 ; Yang and Li 2009 ), with Nomoto and colleagues concluding that
fi sh isolates differed by sequencing and phylogenetic analysis of the sodA
manganese- dependent superoxide dismutase gene from pigs (Nomoto et al. 2008 ).
Diagnosis
Latex beads were coated with recombinant surface immunogenic protein and used
in slide agglutination when positive responses were obtained with sera from infected
farmed amberjack ( Seriola dumerili). Negative responses were recorded with sera
from non-infected fi sh and from healthy vaccinates, i.e. fi sh that received
Lactococcus garvieae and Str. iniae vaccine (Nishiki et al. 2014 ).
Box 2.13: Streptococcus dysgalactiae subsp. dysgalactiae
White colonies develop in 48–72 h at 25 °C. Cultures comprise Lancefi eld
serological group C, catalase-negative, α-haemolytic on sheep blood
(ß- haemolytic after prolonged incubation), Gram-positive cocci, which form
long chains. Electron microscopy reveals fi mbriae-like structures surrounding
the cell wall. Growth does not occur at 10 or 45 °C, or at pH 9.6. Resistance
is not recorded to 40 % bile salts. The Voges Proskauer reaction is negative.
Aesculin and sodium hippurate are not hydrolysed. ß-glucuronidase,
α-glucosidase, acid and alkaline phosphatase and leucine arylamidase are
produced, but not pyrolidonylamidase, α-or ß-galactosidase (Yang and Li
2009 ). Acid is produced at 37 °C from trehalose and amygdalin, but not from
arabinose, inulin, lactose, mannitol, raffi nose or sorbitol (Nomoto et al. 2004 ;
2006 ).
2 Gram-Positive Bacteria (Anaerobes and ‘Lactic Acid’ Bacteria)
with septicaemia and subcutaneous abscesses in the tail region of Nile tilapia in
Brazil (Netto et al. 2011 ). The organism has also been recovered from diseased
Amur sturgeon ( Acipenser schrenckii ) in China (Yang and Li 2009 ).
Isolation
Str. dysgalactiae has been recovered as orange colonies on Todd-Hewitt agar supplemented with 30 μg/ml of Congo red with incubation at 37 °C for 30 h (Abdelsalam
et al. 2009 ). These could be readily distinguished from Lactococcus garvieae that
produced white or pale orange colonies on the media (Abdelsalam et al. 2009 ).
Characteristics of the Pathogen
Identifi cation was confi rmed by the results of 16S rDNA sequencing (Nomoto
et al. 2004 ; 2006 ; Yang and Li 2009 ), with Nomoto and colleagues concluding that
fi sh isolates differed by sequencing and phylogenetic analysis of the sodA
manganese- dependent superoxide dismutase gene from pigs (Nomoto et al. 2008 ).
Diagnosis
Latex beads were coated with recombinant surface immunogenic protein and used
in slide agglutination when positive responses were obtained with sera from infected
farmed amberjack ( Seriola dumerili). Negative responses were recorded with sera
from non-infected fi sh and from healthy vaccinates, i.e. fi sh that received
Lactococcus garvieae and Str. iniae vaccine (Nishiki et al. 2014 ).
Box 2.13: Streptococcus dysgalactiae subsp. dysgalactiae
White colonies develop in 48–72 h at 25 °C. Cultures comprise Lancefi eld
serological group C, catalase-negative, α-haemolytic on sheep blood
(ß- haemolytic after prolonged incubation), Gram-positive cocci, which form
long chains. Electron microscopy reveals fi mbriae-like structures surrounding
the cell wall. Growth does not occur at 10 or 45 °C, or at pH 9.6. Resistance
is not recorded to 40 % bile salts. The Voges Proskauer reaction is negative.
Aesculin and sodium hippurate are not hydrolysed. ß-glucuronidase,
α-glucosidase, acid and alkaline phosphatase and leucine arylamidase are
produced, but not pyrolidonylamidase, α-or ß-galactosidase (Yang and Li
2009 ). Acid is produced at 37 °C from trehalose and amygdalin, but not from
arabinose, inulin, lactose, mannitol, raffi nose or sorbitol (Nomoto et al. 2004 ;
2006 ).
2 Gram-Positive Bacteria (Anaerobes and ‘Lactic Acid’ Bacteria)