A Loop-Mediated Isothermal Amplification Method Targeting the fbsB Gene for Rapid Detection of Streptococcus agalactiae, the Causative Agent of Streptococcosis in Farmed Fish

Abstract

The purpose of this study was to develop a loop-mediated isothermal amplification (LAMP) method for rapid, sensitive, and simple detection of Streptococcus agalactiae in farmed fish. A set of four primers, two outer and two inner, was designed from the fibrinogen-binding (fbsB) proteins gene sequence of S. agalactiae, and conditions for LAMP were optimized as incubation of all reagents for 60 min at 64°C. LAMP products were judged by agar gel electrophoresis as well as the naked eye after development by Synergy Brands Green I (SYBR Green I). Sensitivity of the assay was 2.8 × 103 CFU/ml (2.8 CFU per reaction) and no positive amplification was detected for other related bacteria. This LAMP method can be used to detect S. agalactiae infection in the laboratory and the field.