65
Characteristics of the Pathogen
Isolates were identifi ed by phenotypic (Rapid ID32 and API 50CH systems) and
genotypic data (16S rRNA sequencing) as Str. parauberis; an organism known previously as Str. uberis genotype II. Eighteen isolates recovered from diseased turbot
in Northwest Spain (Galicia) were subjected to ribotyping and RAPD analyses with
the data demonstrating marked homogeneity among the cultures (Romalde et al.
1999 ). Two serotypes are recognised (Kanai et al. 2009 ; Han et al. 2011a ), and the
complete genome sequence of serotype I has been determined revealing the presence of a single chromosome of 2,143,887 bp containing 1,868 predicted coding
sequences (Nho et al. 2011 ). Serotype I (may be subdivided into Ia, Ib and Ic; Kanai
et al. 2015 ) is the more pathogenic of the two in experiments with olive fl ounder
(Han et al. 2011a ).
There was a 100 % sequence homology between the fi sh isolates and Str. parauberis. The only reliable difference between the turbot isolates and the type strain
concerned the action on D-raffi nose which was negative for the latter (Doménech
et al. 1996 ).
Diagnosis
RT-PCR, using the Taq Man probe assay targeting the gyrB gene sequences, detected
only 10 fg of Str. parauberis genomic DNA/reaction specifi cally and reproducibly
(Nguyen et al. 2016 ).
Epizootiology
Work has demonstrated that Str. parauberis has the potential to survive in the marine
environment in a dormant, i.e. non-cultured form, after an initial culturable phase
that lasted for approximately 1 and 6-months in water and sediment, respectively
(Currás et al. 2002 ). The addition of nutrients to the experimental microcosms led
to a return to a culturable state (Currás et al. 2002 ). Also, Str. parauberis has been
associated with raw milk and bovine mastitis (Doménech et al. 1996 ).
Box 2.17: Streptococcus parauberis
After overnight incubation, pure cultures produce whitish slightly α -haemolytic colonies of 1.5–2 mm in diameter. These contain non-motile encapsulated Gram-positive short rods/cocco-bacilli in pairs or short chains, which
produce alkaline phosphatase, α -galactosidase, ß-glucuronidase and pyrrolidonyl arylamidase, but not catalase, indole or catalase, grow at 10–37 °C but
not at 4 or 45 °C, in 4.5 but not 6.5 % (w/v) sodium chloride or at pH 9.6 or
on MacConkey agar, and degrade arginine and hippurate (some strains).
Streptococcaceae Representatives
Characteristics of the Pathogen
Isolates were identifi ed by phenotypic (Rapid ID32 and API 50CH systems) and
genotypic data (16S rRNA sequencing) as Str. parauberis; an organism known previously as Str. uberis genotype II. Eighteen isolates recovered from diseased turbot
in Northwest Spain (Galicia) were subjected to ribotyping and RAPD analyses with
the data demonstrating marked homogeneity among the cultures (Romalde et al.
1999 ). Two serotypes are recognised (Kanai et al. 2009 ; Han et al. 2011a ), and the
complete genome sequence of serotype I has been determined revealing the presence of a single chromosome of 2,143,887 bp containing 1,868 predicted coding
sequences (Nho et al. 2011 ). Serotype I (may be subdivided into Ia, Ib and Ic; Kanai
et al. 2015 ) is the more pathogenic of the two in experiments with olive fl ounder
(Han et al. 2011a ).
There was a 100 % sequence homology between the fi sh isolates and Str. parauberis. The only reliable difference between the turbot isolates and the type strain
concerned the action on D-raffi nose which was negative for the latter (Doménech
et al. 1996 ).
Diagnosis
RT-PCR, using the Taq Man probe assay targeting the gyrB gene sequences, detected
only 10 fg of Str. parauberis genomic DNA/reaction specifi cally and reproducibly
(Nguyen et al. 2016 ).
Epizootiology
Work has demonstrated that Str. parauberis has the potential to survive in the marine
environment in a dormant, i.e. non-cultured form, after an initial culturable phase
that lasted for approximately 1 and 6-months in water and sediment, respectively
(Currás et al. 2002 ). The addition of nutrients to the experimental microcosms led
to a return to a culturable state (Currás et al. 2002 ). Also, Str. parauberis has been
associated with raw milk and bovine mastitis (Doménech et al. 1996 ).
Box 2.17: Streptococcus parauberis
After overnight incubation, pure cultures produce whitish slightly α -haemolytic colonies of 1.5–2 mm in diameter. These contain non-motile encapsulated Gram-positive short rods/cocco-bacilli in pairs or short chains, which
produce alkaline phosphatase, α -galactosidase, ß-glucuronidase and pyrrolidonyl arylamidase, but not catalase, indole or catalase, grow at 10–37 °C but
not at 4 or 45 °C, in 4.5 but not 6.5 % (w/v) sodium chloride or at pH 9.6 or
on MacConkey agar, and degrade arginine and hippurate (some strains).
Streptococcaceae Representatives