Streptococcus agalactiae INFECTION ON TILAPIA (Oreochromis niloticus) IN CIRATA RESERVOIR, WEST JAVA
Abstract: Streptococcosis is
one of bacterial diseases in the culture of Tilapia, Oreochromis niloticus and
has caused significant economic losses. Streptococcus iniae, is known as
pathogen to marine and freshwater fishes whereas Streptococcus agalactiae is
known as pathogen to Tilapia. The isolation and characterization of four
isolates of S. agalactiae, were described from an infected Tilapia from Cirata
Reservoir, West Java, in July 2008. Conventional and rapid identification
systems were used to determine isolates of S. agalactiae from brain and kidney
tissues. In this paper, we have characterized S. agalactiae and this was the
first isolation of this bacteria from fish. The isolates were gram positive,
catalase-negative, oxidase-negative, haemolytic cocci
colonies on blood agar. All of the of isolates were biochemically
characterized with the API 20 Strep System (bioMerieux). Bacterial chromosomal
DNA used in PCR assay was extracted by heating method. The forward primer is
Sdi 61: 5’-AGGAAACCTGCCATTTGCG-3’ and the reverse primer is Sdi 252: 5’-CAATCTATTTCTAGATCGTGG-3’
with gene target 16S intergenic spacer and it has 192 bp in length. These
primers were designed by Alpha DNA (Montreal, Quebec). The biochemical patterns
of four isolates were rather different although almost all traits were similar
with the exception of pyroglutamic acid (pyra) and L-arginin (ADH), for which
we observed negative and positive reaction in this study. Therefore, some of
the biochemical characteristics of the four isolates did not fit 100% with the
typical patterns of S. agalactiae. However, the PCR result showed that this PCR
assay is an effective tool for rapid and specific detection of S. agalactiae,
the main pathogens involved in warm-water streptococcosis, obtained from pure
culture of naturally infected fish. Therefore, it could be a useful alternative
for culture-based routine diagnosis of warm-water streptococcal infections in
fish.
Keywords: Streptococcus
agalactiae; tilapia; biochemical characteristic; PCR assay
Author: Angela Mariana
Lusiastuti, Lila Gardenia, Tatik Mufidah, Yani Aryati
Journal Code: jpperikanangg090022
