diagnosed as being S. agalactiae-po

diagnosed as being S. agalactiae-positive by the aforementioned
techniques.
The nested-PCR was highly specific since it did not amplify the
intergene 16S-23S rRNA regions from other Gram-positive fish pathogens,
including S. iniae, L. garviae, and E. faecalis, or from Gramnegative
fish pathogen such as A. hydrophila. These results were
consistent with and extend the findings reported by Berridge et al.
(2001) as they did not find DNA amplification from DNA samples
obtained from pure S. iniae, Streptococcus porcinus, Streptococcus
uberis, Streptococcus dysgalactiae, or fromGram-negative pathogens
such as A. hydrophila, Aeromonas salmonicida or Edwarsiella tarda
bacterial cultures (Berridge et al., 2001). DNA sequencing of the amplified
nested-PCR products from 4 naturally-infected adult red tilapia
indicated no variability in sequence and confirmed the identity of
S. agalactiae.
The detection limit for the technique for amplifying the S. agalactiae
DNA 16S-23S rRNA intergene region without the presence of fish
DNA was 1.58 fg; it was 6.95 fg for S. agalactiae DNA mixed with DNA