Multiplex PCR for simultaneous detection of Streptococcus agalactiae, Streptococcus iniae and Lactococcus garvieae: a case of S. agalactiae infection in cultured Nile tilapia (Oreochromis niloticus) and red tilapia (Oreochromis niloticus x Oreochromis mossambicus)

Abstract

A multiplex PCR (m-PCR) technique was developed for simultaneous detection of the causative agents responsible forstreptococcosis 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, and19.53 pg for S. agalactiae, S. iniae and L. garvieae, respectively. Detection of streptococcosis in healthy and diseased Niletilapia (Oreochromis niloticus) and red tilapia (Oreochromis niloticus x Oreochromis mossambicus) cultured in Paphayomand Bangkaew District, Phatthalung Province and Sichon and Hua Sai District, Nakhon Si Thammarat Province, Thailand, bym-PCR technique showed positive results for S. agalactiae from tilapia cultured in Bangkaew and Hua Sai and negativeresults 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 sensitiveand specific diagnostic tool for simultaneous detection of streptococcosis caused by S. agalactiae, S. iniae and L. garvieaein cultured fish in Thailand.

Keywords

• multiplex PCR
• Streptococcosis
• Streptococcus agalactiae
• Streptococcus iniae
• Lactococcus garvieae
• Tilapia