Akkarawit Itsaro, Naraid Suanyuk, and Chutima Tantikitti

pp. 495 - 500

Abstract

A multiplex PCR (m-PCR) technique was developed for simultaneous detection of the causative agents responsible for
streptococcosis of cultured fish in Thailand i.e., Streptococcus agalactiae, Streptococcus iniae, and Lactococcus garvieae.
The study on the sensitivity of the technique indicated that the minimum detected DNA concentration was 9.76, 39.06, and
19.53 pg for S. agalactiae, S. iniae and L. garvieae, respectively. Detection of streptococcosis in healthy and diseased Nile
tilapia (Oreochromis niloticus) and red tilapia (Oreochromis niloticus x Oreochromis mossambicus) cultured in Paphayom
and Bangkaew District, Phatthalung Province and Sichon and Hua Sai District, Nakhon Si Thammarat Province, Thailand, by
m-PCR technique showed positive results for S. agalactiae from tilapia cultured in Bangkaew and Hua Sai and negative
results for samples from Paphayom and Sichon. The m-PCR results were in accordance with microbiological culture techniques,
which detected S. agalactiae from tilapia cultured in Bangkaew and Hua Sai indicating that our m-PCR assay is a sensitive
and specific diagnostic tool for simultaneous detection of streptococcosis caused by S. agalactiae, S. iniae and L. garvieae
in cultured fish in Thailand.